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Environmental Conditions in Tunnels Thesis

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Abstract

There has been a rapid increase in the construction of tunnels as an effective measure in decreasing the infrastructural impact on our environment, including noise pollution and visual intrusion. However, there is no significant reduction observed in the number of environmental impacts. The choice of tunnels as an alternative to surface roads has rather escalated the levels of pollution and hence, there is an urgent need to consider the environmental issues associated with road traffic. To preserve environment from the construction of these subsurface structures, special concern has to be shown by the developers and engineers involved in the project, since many times, the negligence shown by them can result in gross damage to the environment.

The key issues that should be under consideration include acceptable standards of air quality, adequate visibility, acceptable noise level and all other possible dangers.

Sustainable development depends on the facility of materials required for our activities and the absorption of the wastage generated by our actions. The environment is often affected by of our intentional or unintentional activities. The consequences of these actions affect our lives and pose potential threat to other human beings and species now and in the coming years.

The global competitive environment has made it necessary for the construction companies that they guarantee long-term growth and sustainability for their projects. Adequate measures taken before the construction and after completion of tunneling will improve the sustainability of the structure and the environment as well.

Introduction

“A Tunnel is a closed or roofed structure carrying a load through, or under an obstacle” (Chapter 23: Tunnels, 2006, p.1).

According to NFPA (2001), the obstacle can be a mountain, building, water body or some existing structure that comes on the proposed route of the road. The length of a structure that covers the road over 90 meters long more than that is termed as a tunnel (as cited in Chapter 23: Tunnels, 2006).

Being the most costly parts of the road structure there are many issues that have to be kept under consideration. The construction cost of a tunnel is about ten times higher than the construction of a bridge in the same location. However, there are many reasons that contribute to the viability of a tunnel as an alternative to surface roads (Chapter 23: Tunnels, 2006).

Road tunnels are considered more environment friendly as they reduce congestion, noise and increases visual aesthetics. It allows better air quality to flow in the urban areas, as pollutants produced by traffic are disposed away from public places (Technical manual for design and construction of road tunnels- civil elements, 2013).

There has been a rapid increase in the construction of tunnels as they act as a good option in place of surface roads in decreasing some significant components of the environmental impact including noise pollution and visual intrusion of infrastructures. However, there is no significant reduction observed in the number of environmental impacts. The choice of tunnels as an alternative to surface roads has rather escalated the levels of pollution and hence, there is an urgent need to consider the environmental issues associated with road traffic.

Tunnels, being confined spaces, pose a greater environmental threat due to the vehicle emission. High concentrations of various pollutants are present in the air inside the tunnels due to these emissions. These airborne pollutants can pose unfavorable effects on the environment and human health. The PI ARC tunnel committee carries out assessment of traffic –emissions and the quality of air inside tunnels. The process involves measuring and reproducing pollutant concentrations from the tunnels and then comparing them with the quality standards (Tarada et al., 2011).

To preserve environment from the construction of these subsurface structures, special concern has to be shown by the developers and engineers involved in the project. However, many times, the negligence shown by them can result in gross damage to the environment.

It is important to keep certain issues in mind while designing tunnels so that a healthy and harmless environment prevails inside them. The key issues that should be under consideration include acceptable standards of air quality, adequate visibility, acceptable noise level and all other possible dangers. With increasing use of tunnels, there has been a rising concern on the health and safety related issues among the users. Hence, there is an urgent and unavoidable need for the installation of high quality equipment to meet the safety and health related requirements. These equipments include good quality pollution meters, video cameras, and traffic sensing devices, and installing fire detection system (Jacques& Possoz, 1996).

Sustainable development depends on the facility of materials required for our activities and the absorption of the wastage generated by our actions. The environment is often affected by of our intentional or unintentional activities. The consequences of these actions affect our lives and pose potential threat to other human beings and species now and in the coming years (Halliday, 2012).

Most of the megacities in the world are heading for underground infrastructure construction related to utilities, transportation infrastructure, storm protection, water and wastewater power and other systems. With the growing population, people will require to meet clean water demand and wastewater treatment. Some cities have already initiated their work in this connection by favoring the use of tunnels for this purpose. In 1970, New York City initiated a 60-mile long water tunnel project. This project involves four stages for completion. It is expected to deliver 1.3 billion gallons of water every day to nine million area residents on its completion by the year 2020.The first ever constructed water tunnel of the city was put under operation in 1917 and will remain sustainable for several decades in future.

Tunnels play a significant role in draining excessive water during heavy that may threaten life and property if not dealt with carefully. Many U.S. cities are building underground storage system to treat their collective sewer system.

With the overdevelopment in big cities, the significance of these subsurface infrastructures will escalate. The sustainability of tunnels is very impressive. A section of an age old (1836) railway tunnel from Edge Hill to Lime Street in Liverpool is still functional. The Thames River Tunnel was operating until 2007 as a part of London Underground. The oldest section of London Underground was built in 1860s using cut-and-cover method. Tunnels are made for hundreds of years; therefore, they are economically greater on a life cycle cost basis (Munfah, 2013).

Tunnels have a sustainable future. The lifespan of a tunnel is about 125 years whereas surface roads are sustainable for about 75 years (Technical manual for design and construction of road tunnels- civil elements, 2013).

Aim of research

The aim of this research is to shed light on the impacts that tunnels have on the environment. From the construction to completion, as well as its future impacts it will or may have on the environment. The research will be focusing on the different environmental conditions in tunnels around the globe, the methods used to minimize pollutants and how they differ from country to country. The report will focus on air/noise pollutions, ground water pollutants and the use of resources, materials and energy as direct impact of construction activity on the environment is its use of resources.

Literature Review

Subsurface infrastructures like tunnels are considered a better alternative to surface infrastructures due to many benefits they offer, however, there construction and operation leads to several socio-economic and environmental concerns. There has been extensive research on the issues related to tunnels in the past.

History

The beginning of the tunnel construction dates back to 1000BCE in the Middle East. Primarily the purpose of theses tunnels was protection from the intruders. These tunnels were constructed along a riverbed by simply cut and cover technique. They diverted the river to another course for some time for digging a trench and then covering it to form a tunnel below. Once the construction was over, the river was allowed to flow on its original route with a tunnel beneath it. This old technique of cut and cover is used largely in the New York City for constructing tunnels beneath the streets. The Romans came up with new developments in the tunneling technology in the first century BCE. They improved the cut and cover method and used it for the construction of roads. Besides this, they initiated the construction of tunnels through hard rocks. They formed the tunnels through rocks by heating and cooling them alternatively and then digging horizontally with handheld tools.

This method, however, was not safe for the workers as it generated several hazardous risks like depleted oxygen in the air and toxic smoke and fire creating pollution in the environment. In the year 1843, the first ever tunnel of a huge size and worth was constructed underneath the Thames river in London. The Thames Tunnel was constructed without diverting the original route of the river. Isambard Kingdom Brunel, a civil engineer developed a new method by using a huge vertical metal shield in order to dig the tunnel. This shield worked as a wall against the earth where the work was under development. The workers were able to cut away at the earth through the doors on the face of the shield, which minimized the risk of blowout through the developing end of the tunnel. After completion of work at the desired area, the shield was pushed forward a little with the help of the hydraulic jacks lining the frame of the shield. The workers drag away the loosened earth collected in the shield through the doors. Now the metal tunnel parts were placed in the newly created space by shifting of the shield. The process continues until a well-supported tunnel is constructed behind the shield that keeps burrowing through the earth. Brunel’s Shield leads modern times tunneling.

The development in shield tunneling technique further improved as New York initiated construction of tunnels underneath East River. The credit of beginning tunnel construction in New York goes to the civil engineer Clifforf Millburn Holland. He contributed to the more effective and safer shield tunneling. He introduced the idea of increasing air pressure in the tunnel to minimize the risk of blowout. The riverbed’s force could be combated with the increased air pressure inside the tunnel, which would reproduce the presence of earth. However, this also did not prove to be a foolproof technique and produced hazardous risks for the workers as the human body cannot endure such drastic changes in environmental pressure and may develop hazardous diseases like kaison’s disease or bends.

Many developments in tunneling techniques took place in the twentieth century. An Australian Construction company introduced the rock bolting method of tunneling in 1947, which claimed to make the tunnels safe at the time of some geological movement by securing the walls of the tunnel with the adjoin rock. Another technique that developed in this direction was the Chilled Earth Method of tunneling. In this technique, the Tunnel Boring Machines were used to dig the tunnels by freezing the wet and loose material and as the TBM passes through the frozen earth, the workers.This method is being incorporated in the East Side Access Project below the city of Manhattan fixed prefabricated parts of the tunnel. In Washington DC solid rock tunneling was done deep beneath the city to construct the subway system. Another example of the same kind is the London Tube (Wills, 2011).

Different techniques of tunneling

Different techniques of tunneling have developed over time. Here is an overview of the prevalent modern techniques tunneling and their disposition and disadvantages in different conditions. These techniques include cut and cover method, boring method, sequential mining construction and drill and blast techniques (Tunnel construction methods, n.d.).

Cut-and- Cover Method of Tunneling

This technique involves three relative tasks to be completed and they are: excavating trench, construction of tunnel and covering soil over the excavated tunnel. It is a well-known and old method of tunneling that is suitable for constructing tunnels of different shapes and varying tunnel width. Tunnel construction with this technique is parallel to other road construction work but the digging point is deeper. To minimize the risk of dust and noise emissions to the environment, large excavations are generally carried out under a road deck (Tunnel construction methods, n.d.).

Disadvantages: It allows the emission of dust and noise to greater extent resulting in air and noise pollution. However, in this connection, installation of provisional decks is often done as per the immensity of digging to minimize the environmental impact. The excavation work in this method produces C&D materials in massive quantity that needs to be disposed adequately (Tunnel construction methods, n.d.).

Sequential Technique

This method involves segmentation of the proposed location for tunneling. Generally known as the New Austrian Tunneling Method (NATM), it performs the task of tunneling in parts and sequence. This method is time-consuming, however, is useful in the areas with the existing structures such as sewer and subway as it is not possible to relocate them. Some equipment like road headers and backhoes are required for excavation. The process of tunneling with NATM involves drying and dewatering the ground before excavation. Further, other changes like grouting and freezing of ground are also applied for making the soil suitable for tunneling. This method also produces environmental impact that is limited to a small area near the exaction site (Tunnel construction methods, n.d.).

Disadvantages: The comparatively longer duration consumed by the method may result in possible environmental impacts.

Boring Technique

Long tunnels are constructed with the use of Tunnel Boring Machines (TBM). This is an effective technique for excavating solid rocks. It is important to use different equipments suitable for different rock masses and geological conditions while using this technique. TBM can bore a long section of rock with appropriate geological steadiness. However, extremely hard rocks may affect the efficacy of the TBM and cause damage to its rock cutter, which may hinder the progress of tunneling. This method reduces the risks of environmental impacts of noise dust and visual on susceptible workers. This impact is limited to locations near launching, retrieval ducts. Local traffic is not disturbed, and excavation related environmental impacts are less. The amount of C&D material is considerably less than the cut and cover method (Tunnel construction methods, n.d.).

Drill and Blast Technique

This technique requires explosives to blast holes on the projected tunnel location. The process involves boring blast holes to the required depth with drilling rigs and then placing explosives and time detonators in them. After blasting the passage is cleared by removing the rock waste and soils from there. The process continues until the passage for the tunnel is cleared. However, ground has to be between two intense conditions of hard rock and soft ground for the efficacy of this method. The vibration caused by drill and blast method is higher as compared to the bored tunneling but lasts for less duration than that. This method reduces the risk of possible environmental impacts due to noise, dust and visuals as it would be limited to the area adjacent to the proposed site of excavation. The C&D material is produced in less quantity. Local traffic and interruption and related environmental impacts are minimized largely. Drill and Blast method lessens the duration of vibration significantly. Disadvantages: It is not suitable for locations in populated areas. The founding of a temporary magazine site to store the explosives overnight may be unsafe in such areas. Therefore, this method can be restricted to the unpopulated locations (Tunnel construction methods, n.d.). Types of Tunnels

Different types of tunnels are constructed depending on various geotechnical factors as well cost benefit analysis.

Cut-and –Cover Tunnel

Cut-and-Cover tunnels are suitable for not so deep locations. For the construction, a trench is excavated from the ground. This type of tunnels includes contiguous pile wall tunnels; “Top Down” construction; and “Canopy Tube”. Certain factors that should be considered with cut-and –cover tunnels like soil quality, watertable depth, existing material for backfilling and subsequent land use; dewatering requirement; solidity and earth strain on the side walls and loads and overloads on the tunnel roof; access constraints; uplift strengths; and temporary construction load (Chapter 23: Tunnels, 2006).

Cast-in Situ Tunnel in a Waterway

This type of tunnel is constructed in two phases. It involves various drifting underwater work chambers. The first phase of construction is carried out inside a provisional caisson and then the waterway is released above the constructed locale. The second half of the construction involves similar procedure (Chapter 23: Tunnels, 2006).

Immersed Tube Tunnels

In adequate conditions, the immersed tube tunnels work efficiently for underwater crossings. Their construction involves the construction of precast reinforced concrete sections in a dry harbor and then relocating them to the desired location above a dredged waterway. All the precast concrete sections are sunk and connected one by one (Chapter 23: Tunnels, 2006).

Bored Tunnels

These tunnels are constructed in adequate overburdened conditions. Momentary support is essential before the insertion the final lining. The final lining uses already molded and hardened segments, shortcrete or rock bolts depending on the soil type and dug materials. The liners expenditure fluctuates immensely as the type of soil, presence of bulging earth, soft rock or water determines it. In tunnels using TBMs, the process of lining takes place immediately behind the TBM. The sides of the tunnel are stretched and the liner is thrust off as the TBM moves ahead. The TBM cutting head pushes the tunneling substances like earth, rock, clay, water, bentonite and other chemicals out the back end (Chapter 23: Tunnels, 2006).

Tunnels Through Rock: These tunnels are constructed in the conditions of hard, solid medium.The medium may be a soft rock or sandstone or hard rock as granite. This type of tunnel construction involves drilling and blasting or in some cases TBMs (Chapter 23: Tunnels, 2006).

Advantages of Tunnels

The voracious need for mobility due to the swift economic growth has generated the demand for road tunnels to avoid traffic congestion. Globally, the major source of air pollution is traffic emission, which is constantly growing mostly in the urban areas. Moreover, immense population growth causing existing transport bottleneck and limited land availability has also created need for underground roads. In some populated districts such as Boston and Oslo, tunnels are constructed to improve amenity by shifting traffic noise, pollution, and risk of accidents and of visual disfigurement away from surface roads (Air Quality in and Around Traffic Tunnels, 2008).

Advantages:

  • Tunnels are undoubtedly beneficial infrastructures as they stay away from the direct disturbances from surface activities.
  • Road tunnels provide escape from visual disturbances and high noise impacts.
  • The air pollution on the surface roads is also lessened due to tunnels.
  • The most significant advantage of tunnels is that it evades the impact of road on the environment and habitation (Tunnel Vision,1997).
  • Reduction in travelling time
  • Reduction in surface traffic leading to improved air quality and less noise in the residential streets
  • Preservation of natural surroundings and habitats
  • Provide easy access to services and employment areas.
  • Increased efficiency in the transportation of freight
  • Reduction in the fuel consumption and related expenditure and lessened greenhouse gas emission due to less traffic stopping (Sydney road tunnels and air quality, 2012).

Disadvantages of Tunnels

On the other hand, it is perceived that tunnels have not produced the desired results and have further worsened the condition by polluting the air in the surrounding localities with the traffic emissions. It is, therefore, necessary to evaluate the benefits of tunnels keeping in view the dangers they cause because of the traffic displacement. In a road tunnel, the dispersion of pollutant air from traffic is extremely restricted. “This occurs due to the collapsing of a line- emission source of pollution (i. e the road) into a few potentially intense point- sources(ie the ventilation stack and tunnel portals)” (Air Quality in and Around Traffic Tunnels, 2008, pg3). This traffic emission can result in highly polluted air along the route and can pose serious hazards to the health of the tunnel users. Two population groups are under the risk of getting affected by polluted air from the road tunnels. One group comprises of local residents who spend most of their time in the locality including infants, pregnant women, old and frail, who are more prone to air pollution. Another group consists of the population using the tunnel including the regular tunnel users.

  • The construction of road tunnels was initiated with the purpose of reducing the traffic congestion in urban areas; however, it has failed to combat the situation due to rapid increase in the traffic levels in cities.
  • The potential unfavorable health effects created by experiencing traffic jams within the tunnels, anxiety due to delays and irritating noise, unpleasant odor, and sensitivity towards gasses make people more conscious about the air pollution in the road tunnels (Air Quality in and Around Traffic Tunnels, 2008).
  • The existing methods of tunneling and disposition of excavated material are stress boosters for the engineers and tunnel builders. Despite being useful for the society, these structures consume lot of materials and energy and generate emissions disturbing the surrounding environment.
  • The adverse impacts of tunnels involve consumption of electricity, exorbitant cost of human resources,
  • Release of carbon dioxide and other pollutants, solid waste left after excavation and ecological commotion (Zhang et al., 2011).
  • According to Brugge et al., 2007;Sioutas et al.,2005;Delfino et al.,2005,the risk of cardiopulmonary disease, weak lung functioning and asthma is highly associated with particulate air pollution (as cited in Perkins,2012).
  • Ultrafine aerosol particles are generated largely by traffic emissions and are present in large concentrations in the urban environments and near major roadways. The road tunnels create a microenvironment with large vehicular emissions. The features like no sunlight, limited dispersion, closed disposition and other meteorological and boundary position further worsen it (Salma et. al, 2011).
  • Often signify obstruction within the transport work.
  • They require extra awareness and consideration besides all their dependability.
  • Sometimes, life threatening situations arise due to interruptions in road tunnels because of natural calamities like volcano eruptions (Traffic and Safety in Road Tunnels, 2011).
  • The construction of tunnels involves complex technology and intricacy at organizational level. It is also reserved for many safety reasons.
  • The issue of subsidence is also associated with the construction of tunnels.

The most crucial factor that leads to restrict the construction of tunnels for very special cases is the exorbitant amount of expenditure they require. Advancement in technology has caused a fall down in the tunneling prices to some extent in the recent years. However, costs vary in different projects depending on their circumstances.

Another issue with the tunneling is the limited number and their diversified engineering and geological features that restrict the application of innovations. It has an adverse effect on the research and technological advancements in this field (Tunnel Vision, 1997).

Environmental Impact of Tunneling

Air Pollution

In a study, by Cowie et al. (2012) conducted to see the health effects of pollutant air, it was observed that, during combustion, these fossil fuels release pollutant gases into the air. This kind of pollution is associated with high concentrations of carbon monoxide and organic compounds. This emission is a health hazard to both human beings leading to lower respiratory tract symptoms and lower spirometric function chiefly lower FVC (Cowie et al. 2012).

A tunnel study in Maxico the revealed that “a high correlation is found between typical vehicle emission tracer species, including benzene with other aromatic species and isopentane with other aliphatic species ( Araizaga et al ,2012, Para 10).

Sources of Air Pollution

The principal cause of environmental and air pollution is the fast growing traffic. Besides posing hazards to human health, it also disrupts the eco system. Traffic generated pollutant emissions are a serious matter of concern. The burning of fuels like gasoline, LPG, diesel oil etc. in vehicle engines generates a lot of matter. Their unfavorable impact on environment and human beings depends on their chemical solidity and concentration level in the air. These are the main composites in the exhaust gas:

Carbon dioxide

Carbon dioxide is the prominent compound generated by the combustion of fossil fuels. This does not have any direct severe health hazard but leads to the so-called “greenhouse effect”. The amount of this compound, specifically related with the tunnel traffic emissions is not worrisome; however, the worldwide amount poses potential environmental risks. Carbon monoxide

Carbon monoxide is formed in a dropping atmosphere. It generates due to the overall shortness of the combustive or the restricted insufficiency because of the non-homogeneous nature of the fusion of fuel with air. Vehicles with spark ignition and moving at lower speeds generate more CO. The problem can be solved by setting up a catalyst that decreases the release by a factor of 10. (Jacques & Possoz, 1996).

In an inadequately ventilated space, like a tunnel or underground parking, the risk to human health increases drastically, however, there has been a remarkable reduction in CO from exhaust due to improved engines in the vehicles. Smoking tobacco inside a vehicle may increase the health hazards due to additional risk coming from the emissions. It forms COHb when mixes with haemoglobin in our body, weakens the oxygen transporting capacity of blood, and lessens the release of oxygen to the tissues. It proves to be more dangerous during pregnancy and can cause serious cardiovascular risks and short-term neurological disorders. Nitrogen dioxide

According to Svartengren et al , 2000; Bylin et al, 1988;Bylin et al, 1985, the concentrations of nitrogen oxide require adequate control management as these may rise significantly in poor ventilating conditions. WHO guidelines (2006) have restated that nitrogen dioxide is responsible for a number of health effects like increased respiratory problems in children, inception of respiratory problems in infants and bronchitis in children with asthma. It is a matter of concern whether being exposed to nitrogen oxide within an enclosed space like a tunnel may pose health risks (as cited in Air Quality in and Around the Traffic Tunnels, 2008).Few studies on this subject have suggested that people, especially with asthma showed adverse health effects when exposed to the nitrogen dioxide even for short periods.

Particulate Matter

Particulate matter can increase drastically in the tunnels in comparison with the urban air. It is observed that repeated exposure to particulate matters even for brief periods may result in lifetime risk for the in-users. It contains highly toxic and carcinogenic matter in the tunnel environment.

Diesel Exhaust

Vehicles using diesel and petrol engines emit different blends of combustion formations. It contains fine and ultrafine components. It has an intricate internally and externally diverse aerosol system that is based on semi volatile unrefined compounds and soot. The volatile and non-volatile constituents in diesel exhausts are present in the gas as well as particulate phase. Their toxic and carcinogenic character is accountable for the formation of irritant substances while undergoing photochemical reactions oxidation. The United States Office of the Environmental Health Hazard Assessment declares diesel exhaust accountable for the contaminant air that can pose severe inhalation risks and cancer risks in adverse conditions (Air Quality in and Around the Traffic Tunnels, 2008).

Ultrafine Particles

The horrible health effects due to the ambient levels of PM relate to those of ultrafine particles. These include increase in the mortality rate, horrible respiratory hazards, possibility of cardiovascular problems leading to death, asthma (more hazardous for adults than children), increased cardiovascular illness in those with severe heart diseases (Air Quality in and Around the Traffic Tunnels, 2008). Sulfur dioxide

The sulphur content in the fuel is responsible for generating this pollutant in the air. However, its low concentration in diesel, gasoline and zero concentration in LPG leads to only 5% of the SO2 emission by vehicles.Hence, it does not raise major concern in the issues related to tunnel ventilation(Jacques & Possoz, 1996).The health problems due to the emission of sulphur dioxide may pose respiratory problems, and lung dysfunction even after short exposures. No regular measurement actions are carried out for Sulfur dioxide concentrations in the tunnels, however, when and where measured are found within the acceptable limits (Air Quality in and Around the Traffic Tunnels, 2008).

Lead

The possibility of lead emissions is unlikely to prevail in the tunnels as many countries including Australia have restricted the addition of alkyl lead to petrol. Studies on the subject have established that there is a significant straight connection between blood lead concentrations in the people and the average concentration of lead in the air and in gasoline. The possible health risks due to lead exposure are: “minor congenital abnormalities, intrauterine growth retardation, spontaneous abortion, delivery complications, delays in physical and mental development, lower intelligence quotient levels, shortened attention spans, impaired hearing, and increased behavioural problems” (Air Quality in and around Traffic Tunnels, 2008, p.99).

Benzene

In a petrol engine exhaust, benzene is a mixture of unburned benzene from fuel and benzene generated due to the incomplete burning of petrol. The highest concentrations of benzene can be found inside petrol driven vehicle. Smoking inside the vehicle worsens the situation. The adverse effect of benzene are assessed by WHO (2000), which comprise haemototoxity, carcinogenicity and genotoxicity. Due to repeated excessive exposure, these health issues may be relevant to the tunnel users as well as people residing in the neighborhood. Chronic exposure to benzene may lead to bone marrow depression. However, short intense exposure inside a road tunnel is not expected to create these stern effects.

Formaldehyde

Formaldehyde is present everywhere. It is released in a natural course of human actions like burning of organic material like bush fire, tobacco smoking and motor vehicle fuel combustion. It was established by IARC in 2004 that formaldehyde can cause the potential risk of nasopharyngeal cancers and lukenmia. However, the road tunnels are unlikely to cause this risk as they do not exceed the permissible concentrations of formaldehyde (Air Quality in and around Traffic Tunnels, 2008).

Tunnel Temperature

Very long tunnels may create an important environmental issue of increased air temperature due to the heat release from traffic. Specially, in tropical countries it may cause great discomfort to the two-wheeler users inside the tunnel. However, measures have been taken to deal with such conditions by mechanized ventilation and spraying of water into the tunnels so that the underlying heat of evaporation may cool the air inside the tunnel (Tarada et al., 2011).

Maximum Pollutant Criteria

The main two factors that determine the in-tunnel air quality are: the alarming effect of the air pollution on human health when exposed to traffic emissions for short-term, and decreased level of visibility in tunnels. WHO determined the adequate levels of main air pollutants and issued a guideline in 2000 that enclosed several air pollutants like CO, benzene, formaldehyde, NO₂, ozone, PM, SO₂, lead and toluene. The updated version of these guidelines was released for global use in 2005.The guidelines recommend that the “concentration of CO averaged over a15 minute period should not exceed 100mg m-³ (or 90 parts per million [ppm]),and that the exposure at this level should not persist beyond 15 minutes. WHO has set an additional exposure level guide line of 60mg m-³ (50ppm) for 30 minutes (WHO2000) so that the level of car oxyhaemoglobin (COHb) in the blood should not exceed 2.5%” (Air Quality in and Around Traffic Tunnels, 2008, p.13).

World Health Organization guidelines for ambient air quality (carbon monoxide).
Table1.0 World Health Organization guidelines for ambient air quality (carbon monoxide). (Source: Air Quality in and Around Traffic Tunnels, 2008, p.13).

The other factor that determines the standard of air quality in the tunnel is the decreased level of visibility in the tunnels because of the airborne particles. It can cause indirect threats like increasing stress in driving. The direct effect of particulates causing decreased visibility in tunnels does not confirm any obvious effects on health over short-term period. The Permanent International Association of Road Congress (PIARC) has suggested a distinctive visibility criterion of 0.005 m-¹ in regular use and 0.009 m-¹ at the time of any emergency (Air quality in and around traffic tunnels, 2008).

Health Hazards due to Air Pollution

The air quality in the surrounding areas is also affected due to theses traffic emissions. The following table presents the different health hazards that are eminent due to the exposure to air borne pollutants beyond acceptable limits.

Table 1.1Showing health effects of the due to increased concentration level.

Pollutants Various health effects due to increased concentration level
Carbon dioxide Breathing intensifies within 15 minutes, problem in breathing, dizziness, anxiety and sweating, headache, perplexity
Carbon monoxide Within few minutes exposure headache, possibility to collapse in 30 minutes, severe possibilities of coma in 1 hour and death in 1.5 hours.
Sulphur dioxide Instantaneously hazardous, can be fatal within 10 minutes at high concentration levels.
Results in eyes, nose and throat irritation. Chocking and coughing can also occur within few minutes
Silica dust Does not have very serious immediate effect but cumulative exposure may result in lung damage/disease (silicosis) after 15 to 20 years.
May lead to death
Non pollutant
Oxygen depletion Increased rate of respiration
Nausea, inability to be in motion freely, collapse,
may result in heart failure in few minutes

Source: Tunnels under construction, 2006, p.48-49).

Miasma Theory of Pollution

The main theory behind pollution in channels is the miasma theory. Miasma is regarded as one of the most poisonous gases that are made up of decomposed materials. Miasmata are materials whose vapour causes sickness in human health. This theory posits that diseases are caused by pollution. Since there is a link between environmental pollution and construction, maintenance and use of channels, the theory is adaptable to the situation. According to the miasma theory, diseases that attack animals and humankind are caused by environmental factors.

Miasma term, first originated in seventeenth or eighteenth centuries.Miasma is a Latin word that means ‘pollution’ (Sterner, 2007). During the era of Middle ages and Renaissance, the concept of bad air was understood as diseases in general.

Many scholars have related the bad air with many causes. “The most common immediate causes were decaying organic matter (including vegetable matter, animals, and human corpses) and ‘exhalations’ from swamps, marshes, and stagnant water. Other explanations include winds (especially southern winds) that transported corrupt air from another locality and (less commonly) earthquakes that released poisonous gasses trapped inside the earth (e.g., anonymous German treatise). Often these events were attributed to the alignment of the planets and/or supernatural reasons or divine wrath” (Sterner, 2007, p.3).

It was believed that due to some situations, air becomes influential and becomes malignant when it comes in the contact with the discharges of biological rottenness from the earth. Miasms or the originating gases become the cause of diseases. So the Miasma theory established that the diseases spread due poisonous vapour originated from the waste of decaying material that spread foul smell and becomes the cause of air pollution and then diseases (Sterner, 2007).

Such environmental factors include contaminated air, polluted water, and dirty environmental conditions. The miasma theory explains that diseases that are caused by contamination of air, water, and the environment are not transferrable from one person to the other. However, this theory explains that different individuals can acquire the disease causing pathogens directly from contaminated air, water, and the environment. The misasmatic theory has been popular across the world. During the 1850s, this theory was used to explain the reasons why cholera spread speedily in the city of London and in the city of Paris. According to the theory, it was possible to eliminate cholera from people and the two cities through cleaning of the environment and air.

According to Duffy (1990), the miasma theory of diseases was prevailing in the society prior to the bacteriology revolution in 1870s. It was considered the main cause of contagious illness were the toxic and malicious vapours or “miasmas” (as cited in Cutler & Miller, 2004). The notion that people are more prone to the offensive smells was accepted extensively. This idea was strengthened with the evidence of more people falling sick during summer seasons due to prevalence of offensive odors. People were convinced about the adverse effects of polluted water and sewage. However, they were not aware of the core basis of diseases (Cutler & Miller, 2004).

English sanitary reformers got fascinated towards Miasma theory. The theory clarified the reasons for the diseases to be epidemic and it discovered that the areas, occupied by the poor, were filthy, stinking and undrained and that was the reason for spreading the diseases. The new public health movement established that the focus should be on environmental problem instead of personal health and infection and to support this new movement, Sir Edwin Chadwick, the great social and sanitary reformer, William Farr, the famous stastician; Florence Nightingale, the prominent nurse and the idol of the Crimean War and Sir John Simon, the first Medical Officer of Health for London played vital roles (Brief History During the Snow Era, n.d.).

“These terms reflected the early nineteenth century understanding that cities were cleaner than the countryside, and that city air was cleaner than the air in natural environments. The prevailing “miasma” theory viewed places with abundant biological materials — swamps or forests, for example — as introducing harmful gases into the air. Some people recognized that industrial emissions were harmful, but many others saw such emissions as innocuous or even helpful, with numerous public health authorities proclaiming the chemicals released by the burning of coal cleaned biological impurities in the air” (Nagle, 2009,p.15).

In 1348, Master Jacme d’Agramont who was a physician in Spain wrote about the cause of plague. According to him most of the diseases would spread due to polluted air. According to Winslow (1948), the concept of corrupt air was basic in all the plague areas. According to Spanish-Arab physician, Ibn Khatimah (1349), the main cause of plague was corrupted air, which has foul smell. This surrounds people and people inhale this air. The British parliamentary statute of 1388 clearly banned the putting of any kind of refuse like entrails, offal, dung and any other kind of litter into rivers, ditches, waters and other places since such kinds of actions could cause corrupt and infected air and it could develop many illnesses and other types of serious diseases (as cited in Tarada, 2011).

The Miasma theory describes about pollution due to poisonous gases in the air and contaminated water which results into spreading diseases. The Miasma theory can be related to pollution due to tunnelling as the gases in air spread pollution, the consequences of tunnelling could be seen as various types of pollutions, in which air pollution is the major problem.

Noise Pollution and its Environmental Impact

Noise pollution is the other environmental impact that arises due to tunnels mainly during their construction. Different methods used for excavation create a lot of noise and vibration, which causes disturbance to the people in neighboring areas. Besides this, noise levels also soar due to high volume of traffic throughout usual traffic operations.

To minimize the soaring levels of noise, various measures are taken by the companies during the planning and construction of tunnels. The major procedures involved in the process include the use of special pavements having noise-absorbing capacity, using efficient sound insulating and sound proofing barriers. During construction, the use of superior construction machines can lessen the high levels of vibration and noise (Tarada, 2011).

Noise pollution may lead to potential health hazards and disrupted well-being. Elevated levels of noise in the environment exceeding the acceptable limits may lead to various health problems like stress, high blood pressure, sleep loss, decreased concentration levels, reduced learning ability and an overall decline in the quality of life and prospects of peace of mind (Noise Pollution, 2013).

There are evidences that children are more adversely affected by loud noise. People are more affected by elevated noise levels while sleeping. A study conducted by Dr. Arline Bronzaft, showed that children exposed high levels of noise were lagging behind in reading ability. It further established that the same group of children showed improvement in their reading ability when the noise levels reduced (Bronzaft, n. d.).

Table:1.2 The WHO standards for maximum acceptable noise levels. Source: Summary Guidance WHO guidelines relating to environmental noise, 2009, Para 6.

Specific environment Critical effect on health L Aeq
[DB (A)]
Timebase
[Hours]
TheAmax
Exterior Residential Serious annoyance during the day and evening
Moderate discomfort during the day and evening
55
50
16
16

Inside the housing
Interior bedroom
Speech intelligibility and moderate discomfort during the day and evening
Sleep disturbance at night
35
30
16
8

45
Outside the bedroom Sleep disturbance, open window 45 8 60
Classrooms and kindergartens, inside Speech intelligibility, disturbance of information retrieval, communication messages 35 During the class
Restrooms kindergartens, inside Sleep disturbance 30 Resting time 45
Playground, outdoor Discomfort (external source) 55 Playtime
Hospitals, halls / rooms inside Sleep disturbance at night
sleep disturbance, daytime and evening
30
30
8
16
40
Hospitals, treatment rooms, inside Interference with rest and recovery # 1
Outside industrial areas, commercial malls, traffic and domestic Hearing loss 70 24 110
Ceremonies, festivals, entertainment Loss of hearing (clients: <5 times per year) 100 4 110
Speech, outdoor events and indoor Hearing loss 85 1 110
Music and other sounds played in headphones Hearing loss 85 # 4 1 110
Sound pulses generated by toys, fireworks and firearms Hearing loss (adult)
Hearing loss (children)


140 # 2
120 # 2
Parks and protected areas Interruption of the peace # 3

# 1: As low as possible.

# 2: The maximum sound pressure level (not LAF, max) measured at 100 millimeters from the ear.

# 3: quiet outdoor areas should be preserved and the ratio of noise to natural background must be kept as low as possible

# 4: Underground headphones adapted to the value

Urban areas are under great risk of rapidly increasing noise pollution. It is important to keep this aspect under consideration while designing tunnels for such cities “that have a high concentration of acoustical receptors in the immediate vicinity of portals and shafts” (Tarada et al, 2011, para1). However, this kind of traffic-generated noise is not associated with tunnels only. Rather, tunnels and other underground infrastructures are considered friendly to the acoustic environment except some cases where the problem of raised noise level occurs near portals. The impact of noise is assessed before initiating new infrastructure projects, including the construction of tunnels, in all developed nations.

Traffic is the key factor for the noise affecting the environment close to the tunnels. This noise generated inside the tunnel is reflected by the inside layer of the tunnel and stretches to the portals making them more noisy than the open air section. This kind of noise impact is restricted to the close vicinity of the portals and diminishes with distance from the portals. This effect is also eased by existing noise produced by the traffic in open-air sections. Besides this, the ventilation system in tunnels is also a major source of noise impact on the surrounding environment. The fans and airflow through inlets and outlets in transverse ventilation or longitudinal ventilation with extraction shafts are accountable for soaring levels of noise. However, longitudinal ventilation generates comparatively less noise, as the jet fans are located in some distance from the portals and in most cases; silencers are fitted to the fans so that the noise levels do not exceed the acceptable standards (Tarada et al, 2011).

Vibration and its Environmental Impact

Vibration is another issue that is related with the tunnels. During the construction phase vibration is a major problem and poses disturbance due to the explosives and other heavy duty machines, however, road tunnels do not pose much problem in the operational phase as is the case with the rail tunnels. To mitigate the problem of vibration in the operational phase, heavy vehicles should be prohibited to use the tunnel. Fans are another cause of generating vibration, however, these do not have any significant impact on the environment, but a regular monitoring of jet fans is required for reliability and safety purposes (Tarada et al., 2011).

6.8 Impact on groundwater: Tunneling procedures affect the surface and subsurface hydrology of a place during the construction phase and also during the operational phase of tunnels. The impact on water takes place at the time of construction; however, it may linger on for a longer period and can cause problems in the proper functioning and maintenance of the tunnel. Hence, there should be proper measures taken while planning and designing such infrastructures. The hydrology of the surface and subsurface level should be studied adequately before initiating the construction work of the tunnels. For the smooth progress of tunnelling, it is necessary to choose the least destructive course involving least disturbance and shifting of the hydrological patterns and procedures.

In spite of the belief that tunnels can be impermeable, permeable or semi permeable, the fact is that most tunnels are permeable while the construction work is going on and semi-permeable while functional (Tarada et al. 2011).

Water ingress in a tunnel built in segments.
Fig 1.0 Water ingress in a tunnel built in segments. Source: Tarada et al. 2011,para 5.

A very serious issue raised by the construction of infrastructure like tunnels is the drying up of ground water. The irreversible impact on the groundwater supply wells is evident with descending ground water levels due to tunneling. Water impact can be seen in the form of solid releases in the drainage system due to the softening of lime hydroxide with water contact in the concrete lining.

Drainage water flowing and lime calcium hydroxyls precipitating in concrete lined tunnel and construction joint.
Figure 2.0 Drainage water flowing and lime calcium hydroxyls precipitating in concrete lined tunnel and construction joint. Source: Tarada et al. 2011, Para 9).

Tunnels are a possible reason for water table variations in the alluvial deposits. The groundwater rising, due to the tunneling, may pose serious problems to the urban structures (Bonomi & Bellini, 2003).

While tunneling below the groundwater table, the major cause of concern is the stress level and the circulation of pore water pressure. In such cases immediate groundwater drawdown can be seen in the aquifer near the tunnel (Yoo et al, 2007).

Groundwater drawdown can be dangerous for the nearby structures as the decrease in water force affects the soil layers and can cause sinking of the land level. The Romeriksporten tunnel is a perfect example of such case when the high speed tunnel constructions caused about I m of ground sank due to groundwater drawn caused by tunneling. This incidence raised significant issues related to the environmental impact of tunneling (NSREA, 1995, as cited in Yoo, et al, 2007). The example of Seoul Metro expansion project that resulted in a significant drawdown of groundwater level can be considered in this connection. The study relating to this project revealed that tunneling resulting in groundwater drawdown causes a wider and deeper surface trough. In case of groundwater lowering during the construction of a tunnel, around 50% subsidence of the crown and surface may occur before the tunneling route completes (Yoo, et al, 2007).

A rising groundwater table can result during tunnel construction at a shallow depth below the piezometric surface. Tunneling may cause impediment to the groundwater if it is heading in a direction perpendicular to the tunnel axis. In this situation, the rising groundwater table can be dangerous to the urban as well as rural environment. It can have an adverse effect on the structures as well as can influence the local ecosystem by hampering the root system of vegetation. The following conditions may arise due to rising water table:

  • Decrease in bearing capacity of the structures built on shallow foundation
  • Increased water pressure beneath the floor slabs and foundations
  • Lessened strain due to Increased pore water pressure causing potential ground heave
  • Development of profoundly compressed fills beneath foundation of the structures
  • Settlement of inadequately compressed fills under the base of structures due to wetting
  • Potential collapse of grounds with high collapse potential due to saturation by the high rising water table
  • Probable seepage of groundwater or dampness in the basements of structures and service ducts
  • Increased weight on the retaining walls of structures
  • Necessitates drainage in short-term excavations

Johnson (1994) states, besides these potential risks, the threat of contamination from the partly saturated zones is possible due to the increased groundwater table. These contaminants can mix within the aquifer and infect the groundwater. Rising groundwater table may pose the threat of flooding and polluting the surface waterways. It may also affect the highway drainage system. The environmental dangers posed by the rising groundwater tables due to the fast developing underground transportation systems in urban areas call for serious evaluation of the effects of structures like tunnels (as these are generally constructed at shallow depths near the piezometric zone) on the groundwater levels (as cited in Mennos & Kavvadas, 1994).

Waste management Hazardous wastes are released from the tunnels. Such wastes include liquid, solid, and gaseous materials. These hazardous wastes may have high quantities of CFCs that result from various construction activities that are carried out in the tunnels. These materials, which may include toxic substances, radioactive substances, industrial wastes, medical wastes, and solvents are harmful to people and the environment. Industries account for the majority; it is also hazardous to transport the waste. These materials are dangerous to human health since exposure to hazardous wastes can result in the death of thousands of people and animals. The wastes can also cause water, soil, air, and environmental contamination that last for years. Exposure to these materials can also result in cancer, defective births, disorders of the nervous system, and to a certain extent death.

In any construction type, the C&D materials require proper handling management. Construction waste that is generated through excavation is suitable for landfill. The storage, transportation and disposal of the waste should be ensured during the construction process. Moreover, adequate measures should be taken to minimize waste production and to treat it fruitfully through recycling. The following procedures may prove useful in handling the waste generated due to construction work:

  • Maintaining a transitory stockpile to store the waste and utilization of excavated fill materials
  • Backfilling of the stockpiled excavated C&D material instantly after the completion of the tunnel section
  • Transportation of the remaining artificial hard materials to the recycling plant and make provisions of their proper use.
  • Approval for the appropriate sites for final disposal

In order to avoid excessive arising of C&D waste, standard resilient foamwork or plastic facing should be used at the construction site. Wooden hoardings should be avoided and in place of them metal hoardings should be considered as they can be recycled and reused. The maximum possible recycling of the C&D material should be done on-site. Last but not the least, to avoid waste, there should be proper planning and care taken at time of purchase of the construction material (Kwan Tong Line Extension-Environmental Impact Assessment, 2010).

Environmental conditions inside the tunnels around the world

A very fine example is the excavation of the London Water Ring Main (LWRM) that set a world record for completing the tunneling with great speed. The favorable ground conditions led to the speedy excavation with TBM’s in that case. The improvements in cut and cover have also minimized the surface disorder caused by this method earlier (Tunnel Vision, 1997).‎

In an effort to create a steady transportation system to make the urban environment more healthy and sustainable, many cities are occupied in massive tunnel building activities. 1-2 km long tunnels are most common in the urban areas. Five km long tunnels are also constructed in the cities (Air Quality in and Around Traffic Tunnels, 2008).

A distribution of the number of urban tunnels as a function of length from a survey of 55 road tunnels around the world.
Fig. 3.0 A distribution of the number of urban tunnels as a function of length from a survey of 55 road tunnels around the world. Source: Air Quality in and Around Traffic Tunnels,2008, p.4.
Approximate length of new urban road tunnels opened between 1989 and 2007.
Table1. 4 Approximate length of new urban road tunnels opened between 1989 and 2007. Source: Air Quality in and Around Traffic Tunnels, 2008, p.4.

Air Quality, Controversy, and National Approaches

The prevalence of different attitude towards the road tunnels in different parts of the world makes it a controversial issue. Hong Kong has road tunnels longer than 20 km but no community controversy is witnessed in the adjoining areas of these tunnels. The topography and high population density of Hong Kong are some of the factors that demand such long tunnels.

United States has tunnels mostly in the areas away from cities. The first urban road tunnel in the Unites States was constructed by converting the Boston Central Artery freeway to tunnel in 2003.The main concern was to provide effective traffic flow and possibilities of urban development in the surface area after removal of the freeway. However, in Scandinavia, tunnel construction has been focused on the possible improvement in the environment by lessening and shifting traffic impacts. The release, character and control of PM (Particulate matter produced by interaction of studded tyres with the road surface) in tunnels is the focus of study in Scandinavia.

In Australia, various technical and political issues have given rise to the controversies associated with tunnels. The 4 km M5 East tunnel in Sydney, however, has proven to be not posing any risk to the users as the CO levels are within the guidelines issued by the World Health Organization, the community concerns have led to significant changes in the design and functional aspects of the subsequent tunnels for example, Manins 2007.

Tunnel studies in the world

Soderedstunnel, Stockholm

This is a 1.5 km long busy road tunnel located in central Stockholm. it bears the load of approximately 72000 vehicles in a day with a speed limit of 80kmh-1. The two unidirectional tubes consisting two lanes each are ventilated longitudinally. Several studies on this tunnel represent the following datasets. The measurement sites used by the researchers are mostly at 100m and 1000 m depth in the northbound tube.

Published papers on air quality measurements in the Soderledtunnel, Stockholm.
Table1.5 Published papers on air quality measurements in the Soderledtunnel, Stockholm. Source: Air Quality in and Around Traffic Tunnels,2008, p.16.

Hong Kong Mobile Datasets: Hong Kong has a dense tunnel network, which carries constant high traffic loads. Hence, it is ideal location for the study of tunnels. The main features represented by studies on the Hong Kong tunnels are presented in the following table.

Details of Hong Kong based transect studies.
Table 1.6 Details of Hong Kong based transect studies. Source: Air Quality in and Around Traffic Tunnels, 2008, p.17.

Hong Kong Transect Studies

The results of the transect studies of five tunnels in Hong Kong revealed similar results. Chen et al (2002) carried out a survey in 1998-99 winters during daytime and found that the concentration of CO in Cross Harbour, Lion Rock and Eastern Harbour tunnels located in the central areas ranged between 7.6 to 8.5 ppm at peak hour whereas it ranged between 5.6 and 7.6 ppm at normal hour. However, in Tai Lam and Cheung Tsing, which are located in rural area, the concentration of CO was 2.9 – 3.0 ppm, 2.3, and 2.6 at peak hour and at normal hour, respectively. The variation was supposed to be due to variation in the traffic flow in the urban and rural areas (as cited in Air Quality in and Around Traffic Tunnels, 2008). Mui and Shek (2005) also conducted a survey two same tunnels (Lion Rock and Cross Harbour). They surveyed during off-peak hours in summers in 2003.They drew similar results as the previous study by Chen et al(2002) i.e 2-13 ppm, with a mean of 6.5 ppm. Chow and Chan( 2003) also presented the same measurements in their study of the same five tunnels. In their study conducted in the summers of 1999 (as cited in Air Quality in and Around Traffic Tunnels, 2008).

Only difference was witnessed in the Eastern Harbour Tunnel that showed the concentrations of CO surprisingly higher( more than double) than the previous studies. The possible reason for this variation was considered the positioning of the sample inlet (as cited in Air Quality in and Around Traffic Tunnels, 2008). M5East tunnel, Sydney: In the transect study (SESPHU 2003 as cited in Air in and Around Traffic Tunnels, 2008) conducted on M5 East tunnel in Sydney, 2002, the Co concentrations were measured between 5.3 to 38.7 ppm. Morning concentrations were comparatively lower (means of17.2 and 23.2 ppm, respectively).There was no significant variation found depending on the direction. These measurements are comparatively higher than the values measured in Hong Kong. The reasons may be that the M5 East tunnel is extremely busy and bears the load of a large number of vehicles.

The proportion of HDV’s is comparatively low. That makes a significant difference as one diesel-fuelled truck is capable of generating particle pollution equivalent to particle pollution produced by 20cars. Another considerable issue is the congestion level. The expected exit time for a 4 km tunnel is 2.7 minutes with a speed limit of 90 km per hour. But the study (SESPHU 2003) revealed that speed was comparatively slow i.e.50 and 24 km per hour in the east bound and westbound tube, respectively. In congested conditions and relatively slow speed, CO emissions increase drastically (Air Quality in and Around Traffic Tunnels, 2008). Tunnel openings are the center of any assessment related to tunnel air-quality measurement. The pollutants are accumulated inside the tunnel in high concentrations and release through the stacks and the portals. Therefore, these locations are best suited for the study of the environment inside the tunnel (Air Quality in and Around Traffic Tunnels, 2008).

Environmental conditions inside Tunnels in Australia

Public dissatisfaction over the freeway network gradually impeded their completion globally including Australia. Subsequently, the change in the scheme design of the proposed Eastern Distributer in Woolloomooloo, Sydney, from a freeway to a tunnel, prevented the demolition of many houses on its route. The technology and equipment of tunneling have improved over time; however, its environmental effects have raised public dissatisfaction to their construction. Tunneling construction is a continuous process and it causes a lot of noise at the sites. To prevent such inconvenience, acoustic noise sheds have become an integral part of city worksites. These sheds are useful in controlling noise and dust due to the ongoing construction work.

Another critical issue associated with tunneling is the impact on groundwater. The need to prevent the drawdown in the water table has generated the need for design solutions in tunneling. In Melbourne and Brisbane, such solutions have been designed to prevent the effect of tunneling on groundwater. The East Link tunnel in Melbourne had to be a watertight structure as the creek ran above the tunnel. A hybrid precast or cast- insitsu lining solution was adopted to allow very tight leakage into the tunnel after its completion. In other cases such as Clem7 (Brisbane) and Airport Link (Brisbane) full segmental lined solutions are fixed behind a TBM. Further, vibration caused by mechanical and TBM tunneling is another cause of concern. This issue was closely studied at the construction site of Clem7. However, vibration is not a serious or long-lasting issue as it disappears with the shifting of construction from that particular residential area. Lastly, air pollution due to ventilators installed in the tunnels can be tackled with improvement in vehicle fleet. Increased use of electric and hybrid vehicles can reduce the issue of air pollution from traffic emissions in course of time.

The increasing pollution in the air is a major issue of concern in Australia. Atmospheric issues rank in a significant place in the list of chief environmental problems in Australia. According to the data presented by the Australian Bureau of Statistics (1999) the major areas of concern shown by the people of Australia were air pollution (29%), Ozone reduction (12%), and greenhouse house effect (9%). New South Wales is highly concerned about the air pollution (35%) and the least concerned state is (18%). People in the urban cities are more concerned about the air pollution (34%) than the non-urban cities (20%) (Atmosphere, 2001). In New South Wales, several actions have been taken to deal with the prevailing air pollution.

Rules for vehicles and fuels are made firm. Tunnels are independently being examined for this purpose. It is compulsory to take the approval from the NSW Minister of Planning after an independent evaluation done by the Department of Planning before the construction of all main urban tunnel roads in NSW. The rules associated with the emission limits and monitoring prerequisites have to be met up by all the operational tunnels. There are efficient air quality monitors placed inside the tunnels and at the portals. Pollutant concentration in the tunnel air is monitored throughout 24 hours a day. The tunnels are ventilated with fresh air using big fans that push the air inside the tunnel and let the polluted air expel through ventilation outlets. To prevent the pollutants congregate in the surface close to the outlets, the elevation of ventilators and speed of air forced out through is carefully assessed (Measures and initiatives to improve air quality in NSW, n.d.).

The air quality outside tunnels complies with the standards set by National Environment Protection Measure: Ambient Air Quality (NEPM) in Australia. These standards are among the most firm standards globally. Such strict actions have led to the sound improvements in the air quality in Australia. WHO has established in a topical study that Australia has some of the most uncontaminated air in the world.

The New Sydney Air Quality Improvement Program (SAQIP) implemented in June2012 in M5 East tunnel and elsewhere in Sydney, by Roads and Maritime Services will ensure the reduce the environmental impact caused by heavy diesel trucks (Sydney road tunnels and air quality, 2012).

Relevant standards set by the NEPM.
Table 1.7. Relevant standards set by the NEPM. Source: Air Quality in and Around the Traffic Tunnels, 2008, p.124.

Air quality management in different tunnels depends on many factors like the length of tunnel, traffic load, quantity of ventilators and jet fans, points for fresh air ingestion, presence of crossover passages and bypasses, substantial restraints inside the tunnel and in operating circumstances of sanction (Sydney road tunnels and air quality, 2012).

To relieve traffic congestion within Sydney, Australia, the trend of extended tunneled roadways came into existence. These tunnels are very long and require ventilation through exhaust stacks to sustain adequate air quality in tunnel and make the tunnel portals free from dispersed emissions. However, exhaust stack emission has created significant concern for the community in Sydney. Previous studies have reported that environmental stressors have contributed to several health problems associated with respiratory system, skin and other allergies.

The M5 East Tunnel

Cains (2003) discusses that the M5 East motorway is ten kilometers long and connects central Sydney with Sydney’s southwest. It is a 4-lane motorway providing dual carriage facility. The four-kilometer dual tunneled section of this motorway is ventilated through a single exhaust stack. The stack is positioned in a valley 900 meters north of the tunnels (as cited in Capon et.al, 2008).

Immediately after the tunneled motorway became functional, the New South Wales Health Department got several complaints from the residents from the adjoining areas related to their health problems, which they associated with the M5East stack exhaust. However, regular monitoring in the local area for an extended period before and after the opening of the tunnels did not show any changes in fine particle, nitrogen dioxide or carbon monoxide concentrations. No change was detectable in selected air toxics concentrations.

A study related to the environmental impacts of the M5East stack established that symptoms related to irritation in eyes, nose and throat are most likely to be associated with the M5 East stack, however, respiratory symptoms were not associated with probable stack emissions (Capon et al., 2003).

To evaluate the genuineness of the study, another co-relational study was carried out in the surrounding locations of M5 East stack. The study did not rule any association between the stack emission and the reported symptoms (Capon et al., 2003).

Unpublished Reports: Several instances have occurred with the users of M5 tunnel like fainting of a driver, and children falling sick after spending 30 minutes in the tunnel. Moreover, many users have complained of getting incapacitated inside the tunnel.

Brisbane North-South Bypass Tunnel

O’ Meara (2004) has studied the variations in the concentrations of different pollutants due to ventilation outlets. The replica of NO₂ and PM variation in the urban air attributable to the Brisbane North-South Bypass tunnel was studied in connection with its impact on community health. The results established negligible immediate health risks, however, O’Meara (2000) mentioned some long-term effects like weakened lung function in children, and potential risk of lung cancer and nonmalignant respiratory deaths (as cited in Air quality in and around traffic tunnels, 2008).

Lane Cove Tunnel

Prior to the construction of the Lane Cove Tunnel, several guidelines were set forth. To deal with air quality inside the tunnel, there would be mechanical ventilation complying with the Department of Urban Affairs and Planning (DUAP) and Environment Protection Authority (EPU).

The proposed design would allow the fresh air to come into the tunnel through the portals and fresh air inlets and the emissions would be released through a vent stack. During the formation of EIS, all possible efficient air treatment systems would be reviewed. To confirm the viability and suitability of the proposed ventilation system, the air dispersion modeling would be carried out. Besides this, community approval would be sought for the suitable location for the vent stack during the formation of EIS.

To deal with noise in the close proximity of both the portals of the tunnel, wide-ranging noise and vibration monitoring program would be prepared, under the wide environmental management plan, during the construction and operational phase of the tunnel (Lane Cove Tunnel: Overview Report, n.d.).

A study undertaken by the Woolcock Institute to find the air pollution levels in the Lane Cove Tunnel vicinity was presented to the NSW Health Department in 2012. The study aimed at the finding the potential difference in the respiratory health of the people residing in the surroundings before and after opening of the Lane Cove Tunnel. The tunnel opened in 2007.The study was carried out under the Woolcock Institute in 2006 and then repeated in 2007 and 2008.The study revealed that after monitoring 3000 residents in the nearby areas, there were no significant changes found in the respiratory health of those people. However, people with respiratory problems can be more prone to the air pollution. Hence, the study recommended the need to deal with the air pollution in general. It suggested that no changes to the operation management were required for the tunnel at present (Respiratory health study findings released on Lane Cove Tunnel, 2012).

The Cross City Tunnel

The Cross City Tunnel is contributing largely to the improved air quality in the central Sydney by diverting approximately 40,000 vehicles from the surface roads to the tunnel.

Air Quality: A ventilation building is located west of Harbour Street. The tunnel is strategically designed for incidents like accidents, vehicle breakdown etc. A unique third tunnel is located under the two tubes that functions as a ventilation tunnel in such cases. The eastbound tunnel transfers air into the third tunnel that is forced out through the ventilation outlet. Other important features are jet fans along the tunnel ceiling, and to control airflow the way in ramps are available. At the west end, there is a major underground ventilation building located near Druitt Street, and at the east end of tunnels, a ventilation crossover passage and ventilation station is positioned. Moreover, there is a bypass fan station at the west end that allows airflow in the bypass ventilation tunnel. Air quality is monitored at different locations in the tunnel with the help of monitors placed in the tunnel.

The Eastern Distributer Tunnel

It is a convenient link for travelling from the north, south and east of the city. It reduces the travelling time to the airport significantly and avoids 19 traffic signals on its way. It runs beneath the densely populated areas of Australia. There are two ventilation buildings in the tunnel for pushing the polluted air out. One is located at Darlinghurst for northbound traffic and another at Surry for southbound traffic. Besides this, jet fans are installed for the circulation of air in the tunnel. The air quality inside the tunnel is monitored throughout the day to keep it in compliance within the standards fixed by the former Minister of Planning (Sydney road tunnels and air quality, 2012).

Environmental management standards across the world

Environmental regulations regarding the environmental impact of tunnels are almost universal.

Australia /New Zealand Standard

Strict legislation, developing economic policies, other procedures promoting environmental fortification and concern shown by the interested parties over environmental issues and sustainable development have made it mandatory for organizations to improve their environmental performance. Consequently, sound environmental presentation is offered by different organizations by evaluating effects of their actions, products and services on the environment through their dependable environmental policy and objectives. Apart from the environmental reviews and audits, it is necessary to integrate a structured management system within the organization for increasing their environmental performance.

International Standard

International standards are set to facilitate the organizations with adequate environmental management system (EMS) comprising legal requirements and important environmental information to accomplish their environmental and economic objectives. However, the commitment shown by the organization in carrying out the implementation of the policy determines the success of the system, which includes development of environmental policy, establishing objectives, carrying out the procedures for the accomplishment of the policy and consider improvements if necessary complying with the International standards. The key motive behind these standards is the environmental safety and sustainability in accordance with the socio-economic requirements. This International Standard works in the cycle recognized as Plan-Do-Check-Act (PDCA).

 Illustrates the PDCA methodology of International Standards.
Fig. 4.0 Illustrates the PDCA methodology of International Standards. Source: Environmental management systems requirements—Requirements with guidance for use, 2004, P.v.

The environmental policy is the chief derivational force for the implementation and improvement of an organization’s environmental management system. It should demonstrate the organization’s conformity to all the legal and other important needs relative to pollution and to constantly improvement in this direction. An organization’s goals and objectives are based on the environmental policy, hence, it should be comprehensible to all the people involved, and should be reviewed regularly to observe changing states of affairs and information. “The area of application (i. e. scope) should be clearly identifiable with the unique nature, scale and environmental impacts of the activities, products and services within the defined scope of the environmental management system” (Environmental management systems requirements—Requirements with guidance for use, 2004, p.11).

The environmental policy should be explained to all the workers for the organization or working on behalf of it. These will also include the contractors who are working at an organization’s facility; however, they may require only the relevant sections of the policy like rules, directives and procedures in alternative forms of policy.

It is highly required that an organization recognizes the environmental features of the consequences of its present and past activities, products and services , planned and novel developments and modified activities associated with its environment management policy. The environmental aspects covered under this policy should include: “emissions to air; releases to water; releases to land; use of raw materials and natural resources, use of energy, energy emitted e.g. heat, radiation, vibration, waste and by-products, and physical attributes e.g. size, shape, colour, appearance (Environmental management systems requirements—Requirements with guidance for use, 2004, p.12). Changing conditions in the environment due to environmental aspects, whether good or bad, are known as the environmental impacts. While recognizing and evaluating the environmental aspects certain matters like location, expenditure and time consumption in the process and accessibility of the consistent data need special consideration (Environmental management systems requirements—Requirements with guidance for use, 2004).

With organizations being more concerned about the environmental matters in connection with their sites and activities or those of potential attainments, there is a growing need for their assessment. An Environmental Assessment of the Site and Organization (EASO) can review these matters and their relative business impacts. Guidelines with respect to the implementation of the EASO are provided by the International standard. These guidelines are for all types of business organizations whether big or small in all parts of the world. EASO activities can observe the following elements in its procedure.

  • Carrying out waste management
  • Handling of the materials and products
  • Carrying out wastewater management
  • Control on air emission
  • Management of water discharge
  • Optimum use of sites
  • Physical conditions that have to be considered during an EASO evaluation process include:
  • Installation of wastewater treatment plants and sewage systems
  • Installation of heating and cooling systems
  • Provision of pipelines and ventilations
  • Provision of restraints, drains and reservoir
  • Provision of containers and tanks for storage purpose,
  • Proper supply of utilities
  • Handling noise, light, heat and vibration
  • Handling dust, particulates, stench and smoke
  • Protection of surface water and surface landscapes
  • Site vicinity, and organizations in the surrounding areas,
  • Assessment of soil and groundwater conditions
  • Treatment of stained and discolored surface
  • Taking care of the flora and fauna
  • Managing buildings, plants and equipment
  • Provision for material storage,
  • Handling hazardous materials, products and substances

Installation of fire and emergency control equipment (Environmental management—Environmental Assessment of Sites and Organizations (EASO), 2003).

Environmental performance Evaluation

Environmental performance of an organization in view of its past and present activities is compared through Environmental Performance Evaluation (EPE).The EPE process involves the model of Plan-Do-Check-Act.

Plan: This step of EPE plan involves the planning of EPE as well as the selection of indicators.

Do: This step involves the collection of appropriate data and its analysis to obtain information on the environmental performance of the organization. Evaluating this information in view of the organization’s environmental performance criteria and lastly reporting this information unfolding the organization’s environmental performance.

Check and Act: This step includes the review of performance and scope for further improvement in future (Environmental management— Environmental performance evaluation—Guidelines, 2000).

Life cycle assessment

Awareness regarding the environmental safety, and the possible impacts linked with products systems and service systems both manufactured and consumed, has led to vigilance in the development of methods to better grasp and diminish these impacts. Life Cycle Assessment (LCA) is an International Standard introduced to describe the principles and outline for carrying out LCA studies and reporting them. LCA evaluates the environmental aspects and the possible impacts from the stage of raw material acquisition to use and disposal. The broad areas of concern are utilization of resources, effects on human health and ecological impact. LCA is among numerous environmental management techniques for tasks like risk management, assessment of environmental acts, environmental auditing and assessment of the environmental impact. It does not relate to the socio-economic features of products or services (Environmental management—Life cycle assessment—-Principles and framework, 1998).

American Standards

American Association of State Highway and Transportation Officials (AASHTO) Technical Committee for Tunnels(T-20) has defined tunnels as the enclosed roadways with vehicle entrance that is limited to portals despite of type of structure or method of construction. Besides the requirements associated with general roadways, some specific considerations are also obligatory for the road tunnels like ventilation, adequate fire protection system, proper lighting and emergency outlet facility. These specific requirements enforce the following added geometric requirements:

Design Standards: The general design guidelines for the road tunnels from the perspective of service level are provided in the AASTHO’s “Green Book”-A Policy on Geometric Design of Highway and Streets (2004). Federal agencies, States and other highway agencies implement these design consideration.

Horizontal and Vertical Alignments

Maximum Grades

The road tunnel grades should provide optimum comfort in driving together with the considerations relating to construction costs and in service and maintenance expenses. The highest grade for main roadway tunnels is 4%. Climbing lanes involving long and sharp uphill grades and should be evaded for ventilation and economic motives. Part-way through a tunnel may cause difficulty in the construction, hence, should be disregarded in the construction of road tunnels.

Horizontal and Vertical Curves: The Horizontal and vertical should be in compliance with the standards set in the Green Book. The horizontal alignment for the road tunnel should be short and maintain possible tunnel length at the departure. It will reduce the number of curves, decrease the distance from end to end and working efficiency will get better. The minimum acceptable horizontal curve radii should comply with the speed of traffic, sight distances and super altitude inside the tunnel. The curve radii should be big and the super elevation rate should be in between 1% to 6%. There has to be strict sight and breaking distance requirements in the tunnels. Provision of sight shelf is necessary to make the tunnel broad in the places where there are curves in the tunnel. Excessive curvature inside the tunnel may restrict sight distance; therefore, it requires careful examination. Other Considerations: It is not advisable to construct road tunnels for bi-directional traffic for safety reasons. At the time of maintenance work, these should be capable of tackling bi-directional traffic. Proper signage outside the tunnel portals is required at such times. The design water level should not exceed 0.005 times in any one year (5OO-year flood level) for prevent tunnels from inundation (Technical manual for design and construction of road tunnels- civil elements, 2013).

To prevent and mitigate the unfavorable incidents in tunnels, various national and international directives are outlined. According to the European Technical Specifications for Interoperability (TSI) on Safety in Railway Tunnels (SRT) directives the four vital areas of concern include “infrastructure, operation, transport network users, and incident management” (How can we optimize tunnel safety and availability, 2010, p.3).

Sustainability

The global competitive environment has made it necessary for the construction companies that they guarantee long-term growth and sustainability for their projects. Chief achievers in establishing and maintaining new standards in tunneling are companies from Germany, Switzerland and Austria. Innovation and sustainability are equally significant in view of the technical consideration that affects the environment and the need for durable solutions. The latest innovations are useless if they pose any harm to the environment. For example, injecting material that is grouted into the ground at some stage in excavation helps in stabilizing, consolidating and preventing water may impact the underground water and can pose serious threats to ecology and human health. For the sustainability of the structures, it is necessary that reliable methods and materials are used for their construction (Tintelnot, 2013). For the sustainability of our environment, special concern is required from the engineers and developers of these subsurface structures, as many times, the negligence shown by them can result in gross damage to the environment.

One such example is the construction of two tube railway tunnel in Europe, where grouting material used for fixing the cracks in the rock contaminated the springs and brooks situated in the adjoining areas. It proved fatal to the cattle using their routine watering places. Drinking water had to be delivered in tanks to the habitants for many months. In another case, damage was caused to the tunnel due to inappropriate treatment of the fissures that led to the discharge of lake water lying above the tunnel route into the tunnel. However, there are cases where engineers set an example for environmental and landscape protection as during the construction of tunnel between Frankfurt and Cologne. The destroyed woodland spread over 33 hectares due to tunneling was compensated by planting 142,500 trees covering equally large area. This was a commendable compensatory project (Haack, 2004).

Procedures and policies to be considered before and after construction of tunnels

Many issues require significant consideration for the sustainability of our environment with all the socio-economic and infrastructural development. To mitigate the potential risk of environmental impact of tunneling, it is necessary to ensure the fulfillment of the following requirements:

EIS

Prior to any infrastructural development, it is important to consider the economic, social, and environmental aspects associated with its construction. Sustainability of the development can be achieved by maintaining a balance between economy and environment. Preparation of Environmental Impact Statement (EIS) during the procedure of environmental assessment is necessary to ensure that significant development decisions are made in view of their environmental impacts. The utility of the project is compared with the potential environmental damage it may pose in future. However, in past environment has suffered loss in such comparisons resulting in environmental damage by being overused and mistreated. Cost-Benefit Analysis (CBA) is combined with EIS for maintaining a balance between economic and environmental issues (Beder, 1997).

Tunnel construction is different from other structure as it lacks in determining exact geological properties throughout the route of the tunnel. To minimize the potential trouble subsequent to the uncertainty of the material property and its inconsistency, it is important that certain measures are taken before starting the construction of a tunnel.

Site Investigation

Reviewing available geological information associated with the construction and thereafter-conducting site investigation to confirm the existing information is necessary to have a better understanding of the site. Adequate assessment of the ground and site leads to the safety of the tunneling work. The site investigation should be conducted keeping in view the character and range of the tunneling project, the location of the project, the environments and anticipated blueprint of the tunnel. The investigation should gather detailed information about the environment of the site, previous history and limitations, the state of ground and groundwater. It should include reasonable evaluation of the methods and designs to be applied to the tunneling project. The followings points should be put under consideration while carrying out the investigation;

  • The study of existing structures regarding their location, their state and influence is important before starting the project. Information regarding on hand services and old mechanisms and any proposed projects in the area should also be collected
  • The detailed study of the topography, hydrology and geology of the site is obligatory.
  • Familiarity with the climate and general weather conditions, seasonal deviations is also required for the proper and timely execution of tunneling work.
  • It is essential to conduct a geophysical survey before starting the tunneling.
  • Assessment of the underground conditions and groundwater state is necessary.
  • Trials of bore holing and blasting should be carried out.

The site investigation would be helpful in understanding all the aspects related to tunnelling in context of the proposed site. The key issues covered in the investigation should include: “rock mass geology, planes of weakness, mechanical properties of soil and rock, planes and rock mass, in-situ rock stress field magnitude and orientation, induced rock stress field due to excavation, potential rock failure mechanisms. The blast damage effects to the rock mass, scale and nature of ground response, possible effects on other working places and installations, groundwater presence and quantity, possible contaminated environments—whether by gases, liquids or solids, including contamination of the groundwater, e.g. chemical plumes, previous historical evidence and data for the area”(Tunnels under Construction, 2006, p.17).

Material in Tunneling For the durability of tunnels, it is important to ensure their proper functioning. Besides technical installations, adequate sealing is a vital part of tunneling. Different methods of sealing can be adopted for sealing that varies with different construction methods. The most common method of sealing in the urban tunnels is the use of watertight concrete along with joint strips and joint plates. The joints between the prefabricated toughened concrete parts are sealed with elastomeric profiles in the shield-driven tunnels. Those tunnels that are not shield-driven and cover long distances are sealed with membrane seals. In case of dealing with seepage water only, these plastic sealing materials are formed as the so-called umbrella seals, but in case of groundwater impact, the membrane seal has to enclose the entire tunnel cross-section.

Much advancement has taken place in the past few years in the modus operandi of membrane sealing. Besides all these safety measures, it is important to recognize that technological experience and a responsible approach is highly required for the proper operation and sustainability of such underground structures. The geologists and engineers must not focus only on carrying out the construction work but also realize their responsibility towards environment and society. Some examples of negligence have resulted in drastic incidents in past for example, the tunnel cave –in that caused an articulated bus to fall into the following gap and the huge earth disintegration at London’s Heathrow Airport. The tunnel builders need to assess their restrictions and act responsibly in view of the safety of crews on work, tunnel users and road users’ residents and surroundings (Haack, 2004).

Sprayed concrete is a material that can be used as a permanent lining in the structures. It is soft in the beginning and immediately slinks under load and has the capacity to bear heavy loads very soon after application. Hence, it works best as a lining, which allows ground deformation. “The material behavior (specifically the increase in stiffness and strength with age) is also compatible with the need to control this deformation so that strain softening in the ground does not lead to failure” (Thomas, 2008, p.5).

Tunnel sustainability and safety

The economic development of a nation is influenced by its strong transport network like rail, road and mass transits. The obstruction, caused by lengthy shutting of damaged tunnels due to incidents like fire or accidents, affect the economy and disturb the transportation system. Hence, it is important to apply safety measures to provide constant availability of tunnels by minimizing the risk of structural damages and applying prompt recovery measures. It is also important to abide by the codes associated with infrastructure and comply by the safety requirements of the users (How can we optimize tunnel safety and availability, 2010).

Early detection

Accidents and fire in the tunnel can demand exorbitant costs. The universal video application platforms can mitigate this problem by identifying, monitoring and reporting the situations and articles that may pose the risk of accidents and fire. This device generates alarm in the incidents of drivers chosen wrong way or lost road, interruption in the easy flow of traffic and violation of rules.

Incident containment

In presence of the highly inflammable materials like petrol or chemicals inside the tunnels, incident containment is a solution prevention of incidents and saving lives as well as the infrastructure. In case of fire improved detection and verification technologies help in detecting the location of fire and also providing information regarding its movement and potential threat to users and fire fighters. Advanced technological devices like, smoke detection solution and fiber optic linear heat detection solution are efficient incident containments, which contribute to the sustainability of tunnels.

Detection of external threats

Air intake shafts are generally at potential risk of getting affected by the outside environmental conditions. Smoke at the opening of air shafts, due to destruction on the surface, can enter the tunnel through them and can reduce visibility inside the tunnel and pose potential risk to the users. Aspiring Smoke Detectors are a wise solution to this situation. These are installed close to the air intake shaft in the tunnel to measure the smoke density. In case of critically elevated smoke level, alarm is triggered.

Quick alarming and safe evacuation

With the help of effective voice evacuation solutions, pre- recorded instructions or live announcements during alarming situations are broadcasted at the time of emergency. Along with this broadcast, the escape route is illuminated with flash lights to make the people aware of the risk and evacuation process speedy.

Critical system protection

The technical rooms containing control cabinets associated with ventilation, traffic signals and fire safety etc. need to be kept running at the time of some critical situation like fire. The advanced S-Line smoke detectors genuine alarm guarantee is apt for such emergencies. With the alarm, the extinguishing starts automatically. Natural agents infuse in the room within seconds extinguish the fire protecting the vital systems from damage.

Hence, coping with the incident response and recovery efficiently, using all innovative and advanced equipments will not only lessen the costs of repairing and traffic diversions and loss due to shutting down but also contribute to the the sustainability of the structure and the environment (How can we optimize tunnel safety and availability, 2010).

Significant development in the technology associated with road tunnels has given way to many big projects. People working in different fields define sustainability with different connotations. Initially, sustainability was applied to the harvesting of natural resources to be maintained for a longer period. In course of time, its domain has expanded covering many other issues like environment, economy and social issues.

With increasing awareness associated with the importance of our natural assets, environmental sustainability became a center of concern for people around the globe According to Robert Paehlke, professor of the Environmental and Resources Studies Program at Trint University, there are three main components of environmental sustainability:

  1. “ecology, habitat, biodiversity, and wilderness
  2. air and water quality( pollution)
  3. Paehlke (1999) States that the conservation, preservation, and management of non-renewable resources [resource sustainability]” (as cited in Berring & Ung, 2003).

According to Goodland et al (1995) Paehlke (1999), environmental sustainability refers to the preservation of these three domains for human interests. It involves the management of resources like harvesting and sinks like emanation (as cited in Berring & Ung, 2003).

Sustainable Construction of Underground Transportation Infrastructure (Scout): The advancement of Trans-European Transport Network involves construction of a number of highways, railways and underground infrastructures. Underground constructions are the best suited to urban areas as they minimize congestion, noise related issues and protection of the natural surroundings and habitats on the ground. In many ventures, waterborne connections are the only probable option to construct intermodal links that join underground stations and airports, parking areas, pedestrian entrance etc. Cut-and –cover tunnels area significant means of building transport infrastructures required for the progress of TEN-T Network. However, there are some issues that are to be abated like safety and cost effectiveness and environmental impact due to construction.

SCOUT aims to introduce cut-and-cover techniques with an innovative approach. This approach focuses on the sustainable construction and environmental considerations. It will involve reduction in the nuisances related with the construction ventures like noise, disruption of traffic, ill treatment of the wastage and dust etc.in the vicinity. This approach focuses on the three key fields of construction procedure: construction design, construction material and construction process. Initiating with the first domain, the focus is to use composite materials known as the fibre-reinforced concrete with enhanced quality for the construction of tunnel walls. Next step is to enhance the designing of the tunnel. It can be obtained by applying the optimized materials and implementing systematic inspection methods. The last and most important target is the use of modular and appropriate equipments for carrying out the tunneling work with minimum environmental impact. Recycling of the waste due to excavation can be an effective measure in this connection (Sustainable Construction of Underground Transportation Infrastructure, 2012).

Future of Tunnels

In the past few years, the transport tunnel construction has significantly increased at global level. This trend is going to increase in the coming years. A study conducted by the Viennese Academy of Sciences revealed that private motoring in Europe will increase by 40% by the year 2030. (Haack, 2002 as cited in Haack, 2004). The Organization for Economic Cooperation and Development (OECD) also assumes that 50% increase in the number of vehicles can be witnessed in Europe by 2020. Another fact conducive to the requirement of more tunnels is the ever-growing population and urbanization. To meet the needs of the cosmic urban regions, it is necessary to opt for underground space so that the quality of life is maintained in such expanded cities. These developments give rise to the potential need of better and advanced infrastructure to secure mobility in future. One solution is probably tunneling as it would secure mobility, provide momentum to transportation and most of all secure the natural landscape and environment (Haack, 2004).

These underground structures are a better alternative to the surface transportation system, however, these demand much attention and expenditure for safety measurements in case of some emergency like fire. The exorbitant cost required for operational activities may also hinder their development in future. Hence, sensible and pragmatic decisions should be taken in the development of these structures to avail ample benefits (Future of Tunnels, 2008).

The westbound Downtown tunnel in Virginia is being closed for weekends for quite some time now. The westbound tunnel was planned to close for 17 weekends for renovation and later the eastbound tube would be blocked for 42 weekends for the purpose (Closing a tunnel shows the future, 2013).

Such circumstances would always come up with the rapidly increasing population and traffic. But it does not mean that tunnels have no future. To provide a sustainable future to tunnels and protect the environment from its adverse impact on the environment, various solutions are proposed by research and development departments of various organizations and established companies.

Eco-tunneling

The focus of existing tunneling procedures is on excavation and least attention is paid to maintain equilibrium between tunnels and nature. Advancement in the scientific approach to ecosystems has paved the way for a new concept in tunneling i.e. ecological tunnel.

Ecological tunnel is the integrating scientific knowledge of ecology and energy conservation within tunnel design, construction and operation towards the major goal of striking a careful balance between human beings, tunnels and nature, which is achieved by the collaboration of green tunneling, green lighting, green lining, green recycling of excavated material” (Zhang et al, 2011).

WSP Safety and fire risk

The vast network of road tunnels requires serious risk assessment throughout its construction and operation procedures. New companies like WSP have come up with various risk management solutions in the designing and planning of tunnels. The centers of concern are the factors that need careful investigation or may hamper the smooth progress of the project. Significant emphasis is laid on the protective systems during this phase and proposed safety measures are evaluated to meet the relative standards. Documentations associated with the risk analysis and risk management system for accidents like fire within the tunnel are prepared and presented. These documents contain chiefly the escape routes design and fire resistance of the character of these structures using advanced temperature calculations. “Computational Fluid Dynamics (CFD) models are used for the advanced computation of the fire and smoke spread along with evacuation simulations designed to calculate walking speeds, identify bottlenecks and validate evacuation strategies”(Future Tunnels Today, n.d.,p.3).

The Air Quality Improvement Plan (AQIP) for M5East tunnel

It was introduced in connection with serious concern shown by public over the air quality and haze due to traffic emissions. It included:

  • Installation of 12 more jet fans for improved air quality in the M5East tunnel
  • Installation of smoky vehicle camera/video system to deal with the problem of haze in the M5East tunnel
  • Trial of air filtration technology for the period of 18 months to assess its viability (Air Quality Improvement Plan, 2006).

The trial period was from March2010 to September 2011.The results are as follow:

Smoky vehicle camera/video: This device prevents the trucks producing smoky emissions from entering the tunnel. It has proved to be beneficial in reducing the haze and improved the air quality in the tunnel. Hence, it needs to be upgraded and applied across the wider Sydney network.

Air filtration plant trial: The air filtration technology did not prove to be feasible. It is expensive to operate and does not draw expected results, hence, not recommended for further use.

The new M5East Air Quality Improvement Program

The new East M5 AQIP (2012) involves installation of upgraded smoky vehicle camera system, expansion of diesel retrofit program, alternative measures to reduce air pollutants in the air quality of M5 East and elsewhere in Sydney. The Minister of Roads and Ports, Duncan Gay in October2012, pronounced the new measures (Managing air quality: the M5 East Motorway and tunnel, 2012).

Several measures have been taken to improve the environmental quality of the tunnels for an innovation in the transportation system and transportation control systems have created many revolutionary changes in the tunnels. The potential trends in tunneling may help in the sustainability of the infrastructure and the environment include

  • Increased use in TBMs and precast concrete tunnel lining support
  • Increased use of robotic systems in construction that will reduce the labor in underground construction
  • Referencing the database of previous projects will improve tunnel analysis
  • Watertight tunnels will reduce the hydrological issues
  • Increased use of electric, hydrogen vehicle fleet, and banned entry for petrol vehicles will reduce the need of emission ventilation system (Asche, 2013).

In view of the previous literature available on tunneling we assume that like any other infrastructure tunnels too have their advantages and disadvantages for mankind as well as nature. The increased pollution level including air pollution, groundwater pollution, noise pollution and waste pose a serious threat our environmental sustainability. Different mitigation efforts are made by government as well as private organizations to improve the environmental conditions within the tunnels through the formation of acceptable standards and introduction of innovative techniques. The present research is an attempt to examine the environmental conditions of some of the tunnels in Australia.

Methodology

The presented research is a qualitative as well as quantitative analysis of the effectiveness and a descriptive survey design to investigate pollutants in tunnels and the corresponding influence of past prevention measures. The findings aim to provide a detailed analysis of the data from a given population to determine the status of the different environmental conditions inside the tunnels and their environmental impact. It also observes the adverse health effects due to different kinds of pollutions created by the construction and operation of the tunnels.

Research Methodology

This part of research deals with research methodology that was employed in conducting the study. It therefore covers the research locale, research design, target population, sample selection, research instruments, conducting, reliability of research instruments, validity of the research instruments, data collection procedures, data analysis, and reporting.

The research methodology that was used in the study is the combination of a qualitative as well as quantitative research method. By using this methodology, the hypotheses of the research questions can be measured, determined, and analyzed. The method also helped in determining the quantity and consistency of results. The method contributed in determining the environmental impact due to the existing environmental conditions in the tunnels effectively.

The method used is a descriptive representation of the phenomenon and collect quantifiable data that can be statistically verified and analyzed to measure the effectiveness of the whole research.

Hence, qualitative research technique was used as it was concerned with the quality or kind. This research technique uses in depth interviews for exploring the better view of the situation. It also intends to know about the understanding of people relating to a particular subject or institution (Research Methodology: An Introduction, n.d.).

Moreover, the survey provided important statistical quantitative data to compliment and confirm the findings presented by qualitative data.

Qualitative research is done with an aim to improve quality and is often considered as ‘Motivational Research’. It also focuses on people’s opinion about particular subjects or institutions (Research Methodology: An Introduction,n.d.).

The statistical survey provides standardized information about the research subject. It is a well-organized way to gather information regarding the understanding of a subject by a large number of respondents. For the purpose of this study, Likert scale, a bipolar scaling method, is used to construct the questionnaire.

Likert scale is used to construct questionnaires to get psychometric replies from the people. It aims at obtaining the degree of agreement or knowing the preferences of the respondents. These scales do not use comparative techniques, but rather evaluate a single feature. The level of agreement has to be shown with the statements in an ordinal scale (Bertram, n.d.).

The Likert Scale is an easy to use system in the surveys. It can be in the form of self- completion questionnaires or can be given as a self-completion part of survey, administered by an interviewer (Brace, 2008). In this system, participants are asked to show their degree of agreement with the given statement. Likert scale system uses five-point scale system where the respondents have to pick any one option from the given five points. Before the final distribution of the questionnaire, a test research was carried out. For this purpose, 10 copies of questionnaire were sent randomly through email. The aim of the pilot study was to make sure that the questionnaire is easy to understand to the participants. Then the questionnaire was sent to the sample selected for the research.

The design is best suited for this study. The rationale behind the choice of the design is that it studies individuals or objects as whole units and not in parts. The design also investigates tunnel environmental conditions in depth with a view of understanding it more broadly.

The purpose of the study is to study the environmental concerns due to tunneling, measures taken for their improvement and pollution prevention performance in the country. Quantitative research methodology is used because data (perceived effectiveness) being tested in this study was through various sources which support it. The study is guided by the actual data collected from the respondents, and the purpose of the study is to analyze them. Such worldview requires the analysis of the strength of the facts and comments.

This worldview entails a systematic procedure and structure in the research process because it follows a rule-bound approach, which meant that this worldview made use of surveys, content analyses, field experiments, and other assessments that will collect verifiable data (Philimore& Goodson, 2004). The worldview also entails the focus on data that will reveal trends, patterns, and statistical relationships. A quantitative research methodology will also be used because the method will utilize open –ended questions as well as close questions; pre-determined approaches, and numeric data (Creswell, 2003).

According to Ross (1999), the quantitative method is more frequently associated with using surveys, which entails studying a large number of subjects that is drawn from a specific population. The research design for this study will employ the use of survey questionnaires and analyzing data gathered from the respondents.

The study involved the use of the questionnaires. These were prepared in advance, and the questions were reviewed to find their relevancy in the concept being investigated. The language used in the questionnaires was relatively moderate to be understood by the people and the procedure was understood.

There were some short answers type questions too where the participants had to answer in yes or no or they have to choose just one answer out of four options.

Population and Sampling Procedure

The population of interest for this study is 50 residents, 10 engineers, and 50 travellers. A large no of participants is used in the sample. Since this is a descriptive design, sampling is a significant process because of the need to obtain an accurate representation of the population (Heck, 2004).

Instrumentation

Survey questionnaires were used as the research instrument. The survey was conducted in two ways- a face to face interview and a telephonic interview. In a face to face interview, all the participants were provided with survey questionnaires in order to determine their perceived level of comparing and contrasting environmental conditions in tunnels towards environmentally sustainable future. The survey instrument was based on the general type of questions related to their understanding about the possible factors, which influences the performance of various pollution prevention measures.There were two types of questions open-ended and closed targeting different groups.

In a telephonic interview similar survey questionnaire was used. Normally telephonic interviews are avoided in the qualitative research as the reliability of data seems not to be very authentic. Also there is much probing required. Though the respondents feel comfortable through a telephonic interview yet, it is perceived that the quality of the data will not be very good (Novick, 2011).

Three sets of the questionnaires were prepared recognizing the different levels of understanding of the situation by the different groups. Though some questions were common in all the three sets but a few questions were asked as per different understanding levels of the different groups.

Reliability

The data collection method that was used needed to be clearly defined and described; in terms of the how instrument has been tested and validated by past studies (Sunderman et al., 2004). The strategy for obtaining good measures for the study involves upholding the relevance and appropriateness of the study for the data collected and the purpose of the study. Thus, the instrument section clearly defined the processes for this method, which will enable future researchers to duplicate the study.

In order to uphold the reliability of this study, the participants were selected according to their various types of professions as engineers, travellers and residents. The questionnaire targeted people from different professional groups as per the setting of its questions.

Data Collection Procedures

It was planned how to reach the people for collecting data. The locale of the study was conducted in various channels. The choice of location was based on how accessible the channels were to the researcher based on Singleton’s (1993) argument that the ideal setting for any study should be easily accessible to the researcher.

The target groups for this research were the various residents, engineers and travellers who use tunnels. A sample that is fully representative of attitude and views of people that use tunnels was selected. Sampling is a technique used by researchers to gather information. It involves selecting individuals or objects from a population or a group for study. The main research instruments to be used in this study were questionnaires. In this case, three sets of questionnaires were prepared for the target groups. These questions targeted the engineers, travellers and the residents.

After making the survey questionnaire, some people like the travelers were approached directly but the engineers of any particular companies were approached through their companies’ administration department which would receive the questionnaire.

The test-retest method was used when one tunnel was selected. Printed copies of the questionnaire were distributed later. The questionnaire was given to the respondents to fill for a later scoring. The participants were given sufficient time to complete the questionnaire. After one week, the same questionnaire was given to the group for scoring.

Primary Research Findings

The primary research was conducted by making questionnaires and those questionnaires were distributed among 110 participants. The participants were divided in three groups. This division was based according to their occupation. It was as follow:

The survey was conducted among 10 engineers through their administrative department and also by sending them mails. Some of them were interviewed through telephone. The results of the interview are shown below

Rating of the presence of various pollutants in Sydney tunnels.
Fig.5.0 Rating of the presence of various pollutants in Sydney tunnels.

While asking them questions about the presence of various pollutants 30% of the engineers agreed on environmental impact due to tunnels. According to them, the principal cause of environmental and air pollution is the fast growing traffic. Besides posing hazards to human health, it also disrupts the eco system. Traffic generated pollutant emissions are a serious matter of concern. Vehicles produce a lot of matter due to fuel burning. Their unfavorable impact on environment and human beings depends on their chemical solidity and concentration level in the air. These are the main composites in the exhaust gas.

Approximately 60% travelers were in favor of this statement that tunnels create environmental impact. Roughly 50% of the residents answered that there is environmental impact due to tunneling.

The engineers were also asked about how to reduce the risks of environmental impact. Some of them answered that installation of provisional decks is often done as per the immensity of digging to minimize the environmental impact. Some told that boring technique reduces the risks of environmental impacts of noise dust and visual on susceptible workers. This impact is limited to locations near launching and retrieval ducts. Local traffic is not disturbed and excavation related environmental impacts are less.

Some engineers answered that drill and blast technique reduces the risk of possible environmental impacts due to noise, dust and visuals as it would be limited to the area adjacent to the proposed site of excavation. Local traffic and interruption and related environmental impacts are minimized largely.

While answering the questions related to noise pollution, 20% engineers got agreed on this point. 50% travelers and 50% residents also admitted that tunneling creates noise pollution. While asking question about air and noise pollution, some of them said, definitely, the tunnels create air and noise pollution. Like air pollution, noise pollution is the other environmental impact that arises due to tunnels mainly during their construction. Different methods used for excavation create a lot of noise and vibration, which causes disturbance to the people in neighboring areas. Besides this, noise levels also soar due to high volume of traffic throughout usual traffic operations. According to them noise pollution could affect adversely. It may lead to potential health hazards and disrupted well-being. Elevated levels of noise in the environment exceeding the acceptable limits may lead to various health problems like stress, high blood pressure, sleep loss, decreased concentration levels, reduced learning ability and an overall decline in the quality of life and prospects of peace of mind. They also further added that to minimize the risk of dust and noise emissions to the environment, large excavations are generally carried out under a road deck.

The survey revealed that air pollution was the major concern by all the participants. According to them during combustion, these fossil fuels release pollutant gases into the air. This kind of pollution is associated with high concentrations of carbon monoxide and organic compounds. This emission is a health hazard to both human beings leading to lower respiratory tract symptoms and lower spirometric function.

The survey also revealed the ground water problem due to tunnelling. 50% engineers showed their concerns related to this. According to them the impact on water takes place at the time of construction; however, it may linger on for a longer period and can cause problems in the proper functioning and maintenance of the tunnel. They further mentioned that a very serious issue raised by the construction of infrastructure like tunnels is the drying up of ground water. The irreversible impact on the groundwater supply wells is evident with descending ground water levels due to tunneling. The participants like residents were keen to answer the questions related to ground water problem while tunnelling. 20% of the residents agreed that tunnels are a possible reason for water variations in the alluvial deposits. The groundwater rising, due to the tunneling, may pose serious problems to the urban structures. This situation is a serious threat to the structures in the surroundings as the reduced water pressures in the soil layers can damage the ground subsidence. Tunnelling may cause impediment to the groundwater if it is heading in a direction perpendicular to the tunnel axis. In this situation, the rising groundwater table can be dangerous to the urban as well as rural environment. It can have an adverse effect on the structures as well as can influence the local ecosystem by hampering the root system of vegetation.

100% engineers showed their foremost apprehension regarding air pollution due to tunneling. 80% travelers and 90% residents expressed their worries through their answers related to air pollution.

Residents having different health problems due to tunneling.
Fig 6.0 Residents having different health problems due to tunneling.

Graph 2 shows the data about residents various health issue due to tunnelling. 59% residents were suffering from headache. 23% residents did not have any health issue due to tunnelling. 10% of the residents were having eyes irritation and 9% residents had coughing problem.

For collecting more reliable and authentic data a survey was conducted specially with the people residing near M5 East tunnel and according to a study the symptoms related to irritation in eyes, nose and throat are most likely to be associated with the M5 East stack.

Table 1.8 Noise pollution level in the M5 Tunnel Sydney at various points (in decibels).

M5 Tunnel Sydney Noise level in decibels
70
75
78
72
79

Table 2.0 above indicates that noise pollution in tunnels is normally above the acceptable levels. From table 2.0, at all points where data on noise pollution was collected, the ratings exceeded that of the accepted level. The graph indicates that in Sydney, noise pollution in tunnels is fairly high.

Waste management is a significant matter of concern during any construction work. It not only cause visual intrusion but may also cause health problems. The residents and travellers agreed that waste laying on the sites of construction presents an unattractive picture as well causes inconvenience while travelling. However, the engineers confirmed that advanced methods of recycling and waste management are being used by most of the companies these days.

Discussion

With a rapid increase in the construction of tunnels as a measure to decrease the environmental impact including air pollution, noise pollution and visual intrusion of infrastructures, groundwater impact and waste management, there has been an emerging need for testing their viability. It has been observed in the present study that the choice of tunnels as an alternative to surface roads has rather escalated the levels of pollution and hence, there is an urgent need to consider the environmental issues associated with road traffic. In spite of various measures taken by the government, health departments and tunnel building companies, the air quality of some significant tunnels like M5 East tunnel has not improved.

Combustion pollutants due to traffic have undoubtedly been a matter of concern for a long time. In a study conducted on the six cities of the United States, it was found that the diseases like lung cancer and cardiopulmonary diseases were directly related with air pollution. The fine particulates along with sulphates were considered the root cause of deaths. “Mortality was more strongly associated with the levels of inhalable fine, and sulphate particles than with the levels of total suspended particles, the sulfer dioxide levels, the nitrogen dioxide levels, or the acidity of aerosol”(Dockery et al 1993, Para 14).

The survey revealed that air pollution was the major concern by all the participants. According to them during combustion, these fossil fuels release pollutant gases into the air. This kind of pollution is associated with high concentrations of carbon monoxide and organic compounds. This emission is a health hazard to both human beings leading to lower respiratory tract symptoms and lower spirometric function.

Krewski et al (2005) have established in their study that Steubenville, Ohio had 26% increase in the all-cause mortality in comparison to the least populated city of Portage, Wisconsin (as cited in Air Quality in and Around Traffic Tunnels, 2008).

Some other studies on the similar subject have also established a link between urban pollution and cardiopulmonary as well as overall mortality (Samet et al, 2000). Fine particulates air pollution is a major cause of cardiopulmonary and lung cancer mortality (Pope et al, 2002).

M5 East has been found to be one amongst the most polluted tunnels in the world. According to a national report on air quality inside the tunnels, the unhealthy air quality inside the tunnel may pose serious health risks to in-users and the people living in the tunnel vicinity. National Health and Medical Research Council has found that the congestion inside the4 km long tunnel carrying 100,000 vehicles everyday can have significant health impacts causing severe asthma, respiratory diseases or cancer. The concentration of some of the pollutants as nitrogen dioxide and particulate matter were very high in the M5 East tunnel. Another pollutant carbon monoxide was also found in maximum concentrations in comparison to the other tunnels in the world.

The M5 East tunnel has not performed satisfactorily and has proved to be a planning disaster. Due to its extraordinary operational use and some technical faults it has been closed for six times since 2002. As a precautionary measure, a filtration plant has been built for air quality improvement in the tunnel (Wallace, 2008).

Considerable connection between air pollution and chronic obstructive pulmonary diseases (COPD) were established in a study conducted upon hospital admissions in six cities of Europe. Ozone was observed as the most strong and consistent pollutant (Anderson et al, 1997).

The present study studied the environmental impact of air pollution and found that children were at a higher risk of health problems when exposed to the tunnels. A related study conducted upon the children showed that traffic related pollution aggravates acute illness in minors and is responsible for asthma and atopy in children and infant mortality (Barnett et al., 2005). The data gathered from respondents reveal that noise pollution is a major problem during the construction phase of a tunnel. However, its impact is reduced in the operational phase. The elevated levels of noise can create potential health vulnerabilities and disrupt well-being of the residents in the surroundings. Elevated levels of noise in the environment exceeding the acceptable limits may lead to various health problems like stress, high blood pressure, sleep loss, decreased concentration levels, reduced learning ability and an overall decline in the quality of life and disrupt peace of mind. The engineers and crew working on the tunnels also admitted the fact and stated that the ongoing large excavations are generally carried out under a road deck to minimize the risk of dust and noise emissions to the environment.

Some engineers approved the use of drill, blast technique since it reduces the risk of possible environmental impacts due to noise, dust, and visuals for being confined to the area adjacent to the proposed site of excavation. In this manner, local traffic and interruption and related environmental impacts are minimized largely. There are evidences shown in the previous study by Dr. Arline Bronzaft that children are adversely affected by loud noise. It may hamper their reading ability and reduce their comprehension capability (Bronzaft, n. d.).

The engineers revealed that the elevated levels of noise can be curtailed through various procedures adopted by the companies during the planning and construction of tunnels for example the use of special roadway having noise-absorbing capacity, using efficient sound insulating and sound proofing barriers. During construction, the use of superior construction machines can lessen the high levels of vibration and noise.

The survey revealed that vibration due to the explosives and other heavy-duty machines is a cause of concern in the habitats near tunnels; however, road tunnels do not pose much problem in the operational phase as is the case with the rail tunnels. To alleviate the problem of vibration in the operational phase, the entry of heavy-duty vehicles should be forbidden in the tunnels.

The engineers confirmed that tunneling have unfavorable effects on the structures of the surrounding areas. It has been found (Mennos & Kavvadas, 1994) that the variation in the groundwater table deteriorates the bearing capacity of the structures and development of profoundly compressed fills beneath foundation of the structures. Potential collapse of grounds due to saturation by the high rising water table and possibility of seepage of groundwater or dampness in the basements of structures and service ducts. It may also pose extra load on the retaining walls of structures. The present survey also found the possibilities of contamination due to the increased groundwater table. Studies show that these contaminants can mix within the aquifer and infect the groundwater (Mennos &Kavvadas, 1994).

Another important issue of concern is the proper management of waste that accumulates during the process of tunneling. It is necessary that the storage, transportation and disposal of the waste should be ensured during the construction process. Moreover, adequate measures should be taken to minimize waste production and to treat it fruitfully through recycling. The tunnel builders take adequate care for the storage, transportation and disposal of the waste in almost all developed countries. Moreover, innovative and better techniques of recycling have made it possible to utilize the waste material fruitfully.

Recommendations

Based on the present study, it can be deduced that tunneling projects require special considerations with respect to their environmental impacts. Although several measures have been adopted to decrease the adversities caused by tunneling to human health and environment, still a greater research is required in this field. The engineers and developers need to adopt innovative methods for construction and operation of the tunnels. Here are few suggestions to maintain a sustainable environment while tunneling:

  • First thing to consider while starting a tunneling project should be to analyse the data related to previous related projects that would provide a guideline for the construction work.
  • TBMs should be utilized in more and more the projects to speed up the construction without less hassle.
  • Construction through robotic system can protect the crew working inside the tunnels from several health hazards.
  • Use of watertight tunnels to deal with the hydrological issues
  • In place of petrol driven vehicles, use of electrically driven and hydrogen vehicle fleet should be promoted.
  • Monitoring of the air quality should start immediately after the tunnel being functional.
  • Safety measures for incidences like fire should be assessed with the help of innovative and advanced computation techniques like Computational Fluid Dynamics models.
  • New concepts like eco-tunneling should be taken into consideration to mitigate the environmental impact induced by the existing tunneling system.
  • Sprayed concrete should be used to provide a permanent lining to the structures. It is soft in the beginning and immediately slinks under load and has the capacity to bear heavy loads very soon after application and hence, works best as a lining.
  • Modular and appropriate equipment should be used to carry out the tunneling work with minimum environmental impact.
  • Recycling of the waste due to excavation would prove an effective measure in minimizing the adverse effects of tunneling on the environment.

Conclusion

Road tunnels are considered more environment friendly as they reduce congestion, noise and increase visual aesthetics. It allows better air quality to flow in the urban areas, as pollutants produced by traffic are disposed away from public places. There has been a rapid increase in the construction of tunnels as they act as a good option in place of surface roads in decreasing some significant components of the environmental impact including noise pollution and visual intrusion of infrastructures. However, there is no significant reduction observed in some of the impacts. The choice of tunnels as an alternative to surface roads has rather escalated the levels of pollution and hence, there is an urgent need to consider the environmental issues associated with road traffic. Tunnels, being confined spaces, pose a greater environmental threat due to the vehicle emission.

Hence, it is important to apply safety measures to provide constant availability of tunnels by minimizing the risk of structural damages and applying prompt recovery measures. It is also important to abide by the codes associated with infrastructure and comply by the safety requirements of the users. The global competitive environment has made it necessary for the construction companies that they guarantee long-term growth and sustainability for their projects. Adequate measures taken before the construction and after completion of tunneling will improve the sustainability of the structure and the environment as well. Programs like Sustainable Construction of Underground Transportation Infrastructure (Scout) and continuous efforts made by established companies like Siemens and WSP are noteworthy in this connection. The measures like eco-tunneling can also prove helpful in sustaining good environmental conditions in future.

References

Anderson,H.R. et al, 1997, Air pollution and daily admissions for chronic obstructive pulmonary disease in 6 European cities: results from the APHEA project. Eur Respir J, vol 10, pp. 1064–1071.

‘Air Quality in and around tunnels’, 2008, The Australia Government Department of Health and Ageing, Web.

‘Air Quality Improvement Plan’, 2006, NSW., Web.

Araizaga, A.E. et al, 2012, Volatile Organic Compound Emissions from Light-Duty Vehicles in Monterrey, Mexico: a Tunnel Study. Int. J. Environ. Res., vol 7, no 2, pp. 277-292.

Asche, H. Tunnelling-delivering modern solution with proven approaches, 2013, Web.

Atmosphere, 2011. Web.

Barnett, A.G. et al, 2005, ‘Air Pollution and Child Respiratory Health’, ATS Journals. vol 171, no 11, p. 1272-1278

Beder,S,1997, ‘Environmental Impact Asessment’, Ecodate, p. 3-8. Web.

Berring, S. & Ung ,D, 2003, ‘A Methodology for Environmentally Informed Decision-Making:Towards Sustainable Projects’, CIFE. Web.

Bertram, D, n. d, , CPSC 681 – Topic Report, Web.

Bonomi, T. & Bellini, R, 2003, The tunnel impact on the groundwater level in an urban area: a modeling approach to forecast it. Materials and Geoenvironment, vo 50, no 1, pp.45-48.

Brace, I, 2008, Questionnaire Design: How to Plan, Structure and Write Survey Material for Effective Market Research,2 ed., Kogan Page Publishers, United States.

n.d. Web.

Bronzaft, A.L, n.d, A Quieter School: An Enriched Learning Environment, Quiet Classrooms, Web.

Capon, A.et al. 2008,, BioMed Central, Web.

Chapter 23, Tunnels. 2006, Department of Roads Roads Planning and Design Manual Closing a tunnel shows the future, Web.

Cowie, C.T. et al, 2012, , PMC. Web.

Creswell, J.W, 2003 ‘Research design: Qualitative, quantitative, and mixed methods approaches.’ Thousand Oaks, CA: Sage Publications.

Cutler,D. & Miller, G. 2004, , Web.

Dockery, W. et al,1993, ‘An Association between Air Pollution and Mortality in Six U.S. Cities’, The New England Journal of Medicine. 329:1753-1759.

Environmental Management— Environmental performance evaluation—Guidelines. 2000.

Environmental Management: Life Cycle Assessment—-Principles and Framework. 1998.

Environmental Management Systems Requirements—Requirements with guidance for use. 2004.

, 2008, Planete TP. Web.

Future Tunnels Today, n.d. WSP, Web.

Haack, A. 2004, Tunnels: Challenges of today and tomorrow, Safe & Reliable Tunnels: Innovative European Achievements, Web.

Halliday,S. 2012, , Web.

Heck, R. 2004. Studying educational and social policy: Theoretical concepts and research methods. Mahwah, NJ: Lawrence Erlbaum Associates.

‘How can we optimize tunnel safety and availability’, 2010, Siemens. Web.

Jacques, E.J. & Possoz, L, 1996, Road tunnels and the environment, Web.

‘Kwan Tong Line Extension-Environmntal Impact Assessment’, 2010. MTR. Web.

‘Lane Cove Tunnel:Overview Report’, n.d. Roads and Traffic Authority, Web.

‘Managing Air Quality: The M5 East Motorway and tunnel’, 2012. NSW. Web.

‘Measures and initiatives to improve air quality in NSW’, n.d. NSW, Web.

Mennos, P.G. & Kavvadas, I.K. 1994, , Web.

Munfah, N. 2013, Digging Deep: tunnel solution for a city-centric America, Web.

Nagle, J.C. 2009, The idea of pollution, University of California. Davis. School of Law, vol 43, no 1.

, 2013. CARRD, Web.

Novick, G. 2011. Res Nurs Health, vol 31, no 4, pp. 391–398. Web.

Perkins, J.L, 2012, , Web.

Phillimore, J. & Goodson, L. 2004 Progress in qualitative research in tourism: Epistemology, ontology and methodology, in Qualitative Research in Tourism: Ontologies, Epistemologies and Methodologies, Phillimore, J. and Goodson, J. (Eds). New York, NY: Routledge.

Pope, C.A. et al, 2002, ‘Lung Cancer Cardiopulmonary Mortality, and Lung-term exposure to Fine Particulate Air Pollution’, American Medical Association, vol. 287.

, 2012, NSW, Web.

n. d, Web.

Ross, J. 1999 Ways of approaching research: Quantitative designs, Web.

Salma I.et al. 2011, ‘Time resolved number concentrations and size distribution of aerosol particles in an urban road tunnel’, Boreal Environment Research, vol16, pp. 262-272.

Samet, J.M. et al. 2000, ‘Fine Particulate Air Pollution and Mortality in 20 U.S. Cities’, 1987–1994, The New England Journal of Medicine, vol 343, pp.1742-1749.

Sterner, C.S.2007, , Web.

Summary Guidance WHO guidelines relating to environmental noise, 2009, Web.

Sunderman, G.et al 2004, ‘Listening to teachers: Realities and No Child Left Behind.’ Harvard Civil Rights Project, pp.12-19

Sustainable Construction of Underground Transportation Infrastructure, 2012. Web.

‘Sydney road tunnels and air quality’, 2012, NSW. Web.

, 2013. U.S. Department of Transportation. Web.

Tarada, F et al. 2011, ‘Environmental Issues linked with operation’, World Road Association Mondiale De La Route, Web.

Thomas, A. 2008, Sprayed Concrete Lined Tunnels, Applied Geotechnics Volume 2, Taylor and Francis, viewed 20 Oct, 2013.

, 2011, Web.

Tintelnot, G. 2013, , Web.

, n.d. Mott Macdonald. Web.

, 2006, Work Cover. Web.

‘Tunnel vision’ 1997, Post, Web.‎

Wallace, N. 2008,, Web.

Wills, Z. 2011, Tunneling history and the east river tunnels, Web.

Yoo C.et al. 2007, Interaction between tunnelling and groundwater – Its impact on tunnel behavior and ground settlement, Web.

Zhang, Z. et al, 2011, ‘Ecological Tunnel for the 21st Century: A New Conception and Methodology’, Journal of Transportation Technologies, vol 1, pp. 54-57.

Abbreviations

  • AASHTO – American Association of State Highway and Transportation Officials
  • AQIP – Air Quality Improvement Plan
  • BCE – Before the Common Era
  • C&D – Construction and Demolition
  • CBA – Cost Benefit Analysis
  • CFCs – Chlorofluorocarbon
  • CFD – Computational Fluid Dynamics
  • CO – Carbon monoxide
  • CO₂ – Carbon dioxide
  • COhb – Caroxyhaemoglobin
  • COPD – Chronic Obstructive Pulmonary Diseases
  • DUAP – Department of Urban Affairs and Planning
  • EASO – Environmental Assessment of the Site and Organization
  • EIS – Environmental Impact Statement
  • EMS – Environmental Management System
  • EPE – Environmental Performance Evaluation
  • EPU – Environment Protection Authority
  • FVC – Forced Vital Capacity
  • HDV – Heavy Duty Vehicle
  • IARC – International Agency for Research on Cancer
  • LCA – Life Cycle Assessment
  • LPG – Liquefied Petrolium Gas
  • NATM – New Austrian Tunnelling Method
  • NCERA – National Society for Real Estate Apprsraisers
  • NEPM – National Environment Protection Measure
  • NFPA – National Fire Protection Association
  • NO₂ – Nitrogen dioxide
  • NSW – New South Wales
  • OECD – Organization for Economic Cooperation and Development
  • PIARC – Permanent International Association of Road Congresses
  • PM – Particulate Matter
  • ppm – Parts per million
  • SAQIP – New Sydney Air Quality Improvement Program
  • SCOUT – Sustainable Construction of Underground Transportation Infrastruture
  • SESPHU – South Eastern Sydney Public Health Unit
  • SO₂ – Sulfer dioxide
  • SRT – Safety in Railway Tunnels
  • TBM – Tunnel Boring Machine
  • TEN-T – Trans European Transport Networks
  • TSI – Technical Specifications for Interoperability
  • WHO – World Health Organization

Appendices

Three Sets of Questionnaire

Questions: Engineers

Open-ended Question:

  1. Do you think that tunnels play a great role in affecting environmental health?
  2. Are the tunnels involved in creating any kind of pollution?.
  3. What kind of diseases can spread due to air pollution?
  4. How can noise pollution affect adversely?
  5. What do you do to minimize the risk of noise emissions?
  6. What measures are taken to reduce the environmental impact while tunnelling?
  7. Have you ever faced any ground water related problem during tunnelling?
  8. What do you do with the C&D waste during construction?

Multiple Choice Questions

  1. What are the types of pollution?:
  1. Water
  2. Noise
  3. Air
  4. all the three
  1. Are the residents affected due to any nearby tunnel?
  1. Yes
  2. No
  1. What could be the cause of pollution?
  1. Soil
  2. Gases
  3. minerals
  4. none of these

Questions: Residents

Open-ended Question:

  1. Do you think that tunnels play a great role in affecting environmental health?
  2. Are the tunnels involved in creating any kind of pollution?.
  3. What kind of diseases can spread due to air pollution?
  4. How can noise pollution affect adversely?
  5. How is the M5 East tunnel affecting your health?
  6. What are the drawbacks of the m5 east tunnel for the residents living nearby that tunnel?
  7. Is there any incidence of water contamination due to tunnelling in your area?

Multiple Choice Questions

  1. What are the types of pollution?:
  1. Water
  2. Noise
  3. Air
  4. all the three
  1. Are the residents affected due to any nearby tunnel?
  1. Yes
  2. No
  1. What could be the cause of pollution?
  1. Soil
  2. Gases
  3. minerals
  4. none of these

One word Answer: Yes/ No

  1. Do you have any respiratory problems after tunnel construction?
  2. Do you feel any inconvenience due to temperature inside the tunnel?
  3. Do you feel any kind of problem like headache/ dizziness/ anxiety/ perplexity?
  4. Do you feel any kind of eyes/ nose/ throat irritation?
  5. Do you feel any kind of choking or coughing?
  6. Do you suffer from any kind of nausea, inability to be in motion freely or collapsing problem?

Questions: Travellers

Open-ended Question:

  1. Do you think that tunnels play a great role in affecting environmental health?
  2. Are the tunnels involved in creating any kind of pollution?.
  3. What kind of diseases can spread due to air pollution?
  4. How can noise pollution affect adversely?
  5. Do you face any problem due to the waste laying on the surface due to construction work?

Multiple Choice Questions

  1. What are the types of pollution?:
  1. Water
  2. Noise
  3. Air
  4. all the three
  1. Are the residents affected due to any nearby tunnel?
  1. Yes
  2. No
  1. What could be the cause of pollution?
  1. Soil
  2. Gases
  3. minerals
  4. none of these

One word Answer: Yes/ No

  1. Do you have any respiratory problems after tunnel construction?
  2. Do you feel any inconvenience due to temperature inside the tunnel?
  3. Do you feel any kind of problem like headache/ dizziness/ anxiety/ perplexity?
  4. Do you feel any kind of eyes/ nose/ throat irritation?
  5. Do you feel any kind of choking or coughing?
  6. Do you suffer from any kind of nausea, inability to be in motion freely or collapsing problem?
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