Introduction
Towards the end of the last century and the wee years of the new millennium, most cities have globally have registered substantial growth in the urban centers. This consequently has seen increased population levels that have poses monumental challenges for public transport, to be able to uphold the passenger integers the metro shuttles have been integrated into most cities as a strategy to contain congestion on the mobility industry.
In our contemporary society electrical and civil engineering has not been left behind by the enormous wave of technological advancements. Light rail systems that support metro buses are being deployed to facilitate rapid transit with minimal frequency in comparison with the heavier mass rapid systems. In this paper, we consider designing a metro shuttle in Riyadh as an alternative mode of transport. The paper, however, is biased, investigating the power supply, types of rails used, and how the metro is controlled. Metro transport systems are powered by light rail systems, a modern variation of transport where trains run separately from the road traffic. On this kind of system, stopovers are normally less and boarding is done over a platform.
Background
Light rail is a modern concept that is versatile in nature and it fits perfectly in the engineering visions of a bus and the heavy metro. In comparison with buses on the streets, it’s ideally an expensive venture to develop although it could also be cheaper in terms of the functionality on a given capacity, It’s however cheaper to build and operate at minimal commercial speed. It is also a form of transport that enhances smooth traveling, it doesn’t emit pollutants over pedestrians and its frequent run is somewhat economical.
Comparisons between Lisbon, Singapore, and Montreal Metro
Lisbon metro is a superlative transport system with numerous satiations that expediently and economically enhances swift transportation around the city. The metro stations exhibit magnificent artwork, which makes the metro in the offing slightly satisfying. The metro system offers an easy workout for tourists than buses. Lisbon’s metro however runs on the underground infrastructure, spotless and competent. Singapore on the extreme runs on a metro infrastructure system that is very expensive since it involves intricate networks that are very expensive to maintain. These networks are fundamentally underground interlocking major roads, rivers, and canals.
Nevertheless, Montreal metros are erected on LAHT (low-alloy high tensile) steel. The trains are pulled together in 3, 6, or 9-car lengths. Every piece of the three-car subdivision component consists of two motor cab cars encircling a trailer car. Each car is 2.5 meters wide and has four wide bi-parting leaf doors on each side for speedy customer entrance egress. The diminutive irritable segment of the cars tolerates easier construction under existing underground utilities.
The Metro services contain four direct-current traction motors coupled to reduction gears and differentials. Montreal’s metro trains use electromagnetic brakes, which create retarding forces against the side rails of the track. The electromagnetic brakes are generated by the train’s kinetic energy until it has slowed down to about 10km/h. The train then uses composite brake pads made of yellow birch injected with peanut oil to bring it to a complete stop.
Two sets are applied against the treads of the steel wheels for friction braking. Hard braking produces a characteristic burnt popcorn scent. Wooden brake shoes perform well, but if subjected to numerous high-speed applications they develop a carbon film that diminishes brake performance.
View of a track from a sand heap bumper-post showing the cross-section of guideways, concrete rollways, and conventional track Rubber tires make the Metro outstandingly quiet, owing to the minimal vibration transmit, this also aids the metro climb the hills more easily and negotiate rotations at high speeds. Nevertheless, the advantages of rubber tires are offset by noise levels generated by traction motors, which are noisier than the typical North American subway car.
Metros can climb slopes of up to 6.5% and economize the most energy when following a humped-station profile (track profiles that descend to accelerate after leaving a station and climb before entering the station). Steel-wheel train technology has undergone significant advances and can better around tight curves, and climb and descend similar grades and slopes. Despite these advances, steel-wheel trains still cannot operate at high speeds (45 mph) on the same steep or tightly curved track profiles as a train equipped with rubber tires.
Metro operation
Switches use conventional points on the standard gauge track to guide trains. Rubber tires keep supporting the full weight of the trains as they go through switches. Guideways are provided in order to ensure there are no gaps in the electrical power supply. All lines but the Yellow Line is equipped with automatic train control. Generally, the train operator supervises the opening and closing of doors, while the train drives it.
The train operator can also drive the train manually at his or her discretion. Signaling is effected through coded pulses sent through the rails. Coded speed orders and station stop positions transmitted through track beacons are captured by beacon readers mounted under the driver cabs. The information sent to the train’s electronic modules conveys speed information, and it is up to the train’s automatic control system computer to conform to the imposed speed.
Additionally, the train computer can receive energy-saving instructions from track beacons, providing the train with 4 different economical coasting modes, plus one mode for maximum performance. In the case of manual control, track speed is displayed on the cab speedometer indicating the maximum permissible speed. The wayside signals consist of point (switch/turnout) position indicators in proximity to switches and inter-station signaling placed at each station stop. Trains often reach their maximum speed of 44-45 mph (70-72 km/h) in 16 to 26 seconds depending on grade and load.
Montreal metro shuttles are driverless; they are computed to stop at given stations by the aide of a comprehensive odometer. Their braking system is coded and executes stoppage commands that are relayed by the track beacons before alighting at a given station.
With extra beacons at the station, accuracy in terms of stopping is achieved. The last beacon is located precisely 12 turns of the wheels from the end of the platform, which helps in improving the overall accuracy of the system. Metros tap two sets of 750-volt direct current (dc) through a bar/third rails on either side of each motor car. Calibration is, therefore, an imperative aspect in regulating and curtailing emerging power surges, arcing, and breaker tripping. Both methods employ electrical raking to assist primary friction braking, hence minimizing the need to surrogate the brake pads.
Montreal metro shuttles are driverless; they are computed to stop at given stations by the aide of a comprehensive odometer. Their braking system is coded and executes stoppage commands that are relayed by the track beacons before alighting at a given station, the beacons have also been mounted at particular stations to ensure a complete stop. The train draws current from two sets of 750-volt direct current by the use of the third rail. To prevent power surge traction technology has been employed in the control system. This research paper is geared towards finding a viable metro transport system in Riyadh based on a vivid comparison between the metro services in Montréal, Lisbon, and Singapore. From the establishment, the Montréal metro system could be the most viable venture in Riyadh.
Stations and Platform Screen Doors
The generously constructed underground terminals are air-conditioned and precisely fitted with a total of 250 escalators and lifts. All remittances are positioned one meter above the highest-ever measured flooding level of the city. They are enhanced with mobile barriers as a safeguard against flooding during the rainy season. Foundational screen doors offer passengers security and air-conditioning component.
They deter passengers from entering the track area on one hand and on the other hand, stop the cooled air from escaping from the air-conditioned stations into the metro tunnel. The platform screen doors always remain closed until the metro shuttle reaches the correct position. The platform door is interconnected with the correct spending train doors via signaling interfaces. The reduced distance between platform screen doors and train doors protects passengers from being trapped flanked by the two sets of doors.
Fare Management System
Passengers fare is normally automated by the use of an automatic fare collection (AFC) system that enhances efficacy in terms of regulation and collection of passenger fares. The metro employs a distance predetermined graduated fare framework, with innumerable smart cards/tokens constituting radio-frequency transceivers as fare media ad automatic blockades that have the ability to decipher and re-encode the fare media to control passengers entry and consequently their exit.
For speed flow in and out of the stations, automated gates are installed with bi-parting leaf flaps and divided into banks of entry only and exit gates. For surveillance reasons, the AFC component is offered in form of station computers and station cash office screening terminals interlocked with the gates, the token purveying machine is used for one-way journeys and the ticket office machines are deployed for multi-journey smart cards through the local networks.
Third Rail
Metro shuttles conduct power through the third rail that taps power from various stations constructed at certain intervals. Through a third rail, the metro is constantly fed with power alongside the rail track. The third manages to draw current through a shoe otherwise known as the slipper.
Third rails are manufactured in various designs and the shoe slides operate as a point of contact. Separation is effected by the use of a wooden paddle between the shoe and the current rail and then trying the shoe up with a strap or rope. Modest systems have their shoes mounted to offer a stable contact via a lever action. Top contact systems have protected covers over them. Side and bottom offer a reliable contact through spring loading.
It should also support completeness of the circuit, right from the energy source to the consuming object and back to the source, this prompts a necessity for the rail return mechanism. To better solve these anomaly steel rails are suitable for this. This also calls for advanced precautious measures to prevent the voltage from getting too high above the zero of the ground. Signaling circuits can also be used although special precaution is needed.
Connecting the return to brushes rubbing on the axle ends completes the circuit. Direct current (dc) is the widely used form of power, it is the best preference owing to the fact that it’s cheap to install and also maintain compared to overhead wires which are so involving. At the same time, alternating current is quite hefty to integrate since slight developments with these structures should comply with the anomalies of interpretability. This ultimately ushers in the option where already built infrastructures have been embedded upon.
Power Supply
Generally, the world’s metros adapt ac power conveyed by the public vendor to dc in order to supply the railway footing power supply system; this is normally at between 600 and 750 v dc third rail interlocks or up to.5KV for overhead catenaries. Modern transport metros deploy the asynchronous ac motors, which support two intricate systems to transform from ac to dc and back to ac.
Conclusion
Riyadh is the fastest growing city in the Middle East with a population so enormous in the sense that prompts the incorporation of contemporary transport infrastructures. Metro modes of transport have exponentially transformed the transport sector to great dimensions. Nevertheless, the Montreal metro system is the most appropriate system to be inaugurated in Riyadh. Since it’s rather cheaper compared to the one entrenched in Singapore and Lisbon. Both Singapore and Lisbon use underground conduits which are so expensive to develop and also maintain.