Introduction
Light Rail or Light Rail Transit (LRT) is a modern urban rail public transport system that offers a balance between the capacities and costs of heavy rail (like metro systems) and traditional streetcars (trams). It incorporates the features of both heavy rail systems and streetcars. Light Rail Vehicles (LRVs) are referred to as a technological evolution of streetcars which incorporates advanced features and flexibility to meet contemporary urban transit needs. These systems typically use electric trains that run mostly on tracks separated from other traffic. However, in some cases, they may share city streets with other vehicles.
Historical Context
The first light rail transit system began operation in 1978 in Edmonton, Alberta, Canada. This system adopted the German Siemens-Duewag U2 technology. Following Edmonton, other cities such as Calgary and San Diego also established their light rail systems in subsequent years.
Comparison To Other Rail Transit Modes
Light Rail Transit (LRT) , with its combination of different Right-of-Way (ROW), offers flexibility in design, engineering, and operations compared to other rail systems.
Rapid Rail Transit (RRT):
Light Rail Vehicles (LRVs) differ from Rapid Rail Transit (RRT) vehicles primarily in their ability to operate in mixed-traffic environments. Due to their design LRVs can easily navigate through city streets which makes them suitable for shared traffic use. In contrast, RRT vehicles, with their larger size are unsuitable for street operation.
One major advantage of LRT systems is their ability to utilise existing streets, which can reduce costs by avoiding the need for expensive subway tunnels or elevated tracks required for RRT systems.
Trams
Light Rail Vehicles (LRVs) are generally superior to streetcars or trams in terms of capacity, speed, and operational flexibility. Modern LRVs often support multiple-unit operations, which enables them to carry more passengers and achieve higher speeds.
Light Metro (LRRT)
A variation of Light Rail Transit (LRT) is Light Rail Rapid Transit (LRRT), frequently known as Light Metro. These systems utilise exclusive Rights-of-Way, advanced train control systems, and floor-level boarding for easy access. These systems can handle passenger volumes similar to full metro systems but are often less expensive to build. This is because Light Rail Vehicles (LRVs) are capable of navigating tighter curves and steeper grades, which reduces the need for extensive and costly infrastructure compared to standard RRT vehicles.
Train Operations
Unlike Rapid Rail Transit systems, which often use automatic train operation (ATO), Light Rail Transit relies on a trained operator because its tracks frequently run alongside roads with car traffic. In these situations, having an operator is essential to maintain safety and ensure high-quality service.
Traction
Most light rail systems are powered by overhead lines, which is a safer option as compared to electrified third rail. The Docklands Light Railway, however, uses an inverted third rail, which is covered for safety, and the power is drawn from the underside.
Tracks
Light Rail Transit (LRT) systems utilise various types of rights-of-way (ROW). In certain cases, LRT operates on fully dedicated tracks, which helps minimise the impact on and from surrounding traffic. However, in urban areas, LRT vehicles sometimes operate in mixed traffic, sharing the road with cars and buses.
Speed
The average operational speed of LRT systems typically ranges from 30 to 50 kilometres per hour (km/h) (about 19 to 31 miles per hour (mph)). However, some modern LRT systems can reach speeds of up to 80 km/h (50 mph) when operating on dedicated rights-of-way. For example, Kuala Lumpur LRT (Malaysia) operates at 80 km/h.
Capacity
LRT systems can transport between 3,000 and 30,000 passengers per hour in one direction, depending on factors such as train frequency and the number of cars in operation.
Development of LRT Systems in India
- Hubballi-Dharwad Light Rail Transit: The twin cities of Hubballi-Dharwad in Karnataka will likely become the first in India to have a Light Rail Transit (LRT) system. This project is planned to be built through a Public-Private Partnership (PPP).
Labour Minister and Dharwad district in-charge Santosh Lad shared that the LRT system is being proposed as a replacement for the current Bus Rapid Transit System (BRTS) to offer better and more sustainable transportation for the people.
Limitations of Light Rail Transit Systems:
Lower Capacity:
LRT systems are typically deployed in cities with populations ranging from 1 to 3 million people. However, in densely populated areas with high passenger volumes, LRT may not be sufficient to meet the demand.
Traffic Interactions:
In mixed-traffic scenarios, LRT systems can be delayed by road traffic, affecting punctuality.
Substantial Initial Investment:
LRT necessitates large initial infrastructure investments. On average, the cost of LRT ranges from $20 million to $80 million per mile. The total cost relies on factors such as the properties of the stations, whether the constructing agency already owns the right-of-way, and the extent to which the rail line is elevated, at ground level, or underground.
Land Acquisition:
At-grade alignments often require the acquisition of land, which can be challenging in dense urban areas.
Advantages of Light Rail Transit Systems
Cost-Effectiveness:
LRT systems are more affordable to build and operate compared to heavy rail systems due to their lighter infrastructure and rolling stock.
Reduced Traffic Congestion:
LRT systems provide an efficient and attractive alternative to private vehicles
Environmentally Friendly:
LRT systems operate on electricity, which helps reduce greenhouse gas emissions and urban air pollution. It makes them a more environmentally friendly transportation option.
Urban Development:
LRT systems encourage transit-oriented development (TOD) around stations, increase real estate values and promote urban renewal in surrounding areas.
Conclusion
Light Rail Transit (LRT) systems offer a practical and cost-efficient solution for urban transportation. They provide flexibility by operating on both dedicated tracks and shared roadways, making them suitable for cities with varying traffic conditions. Although LRT systems have limitations in terms of capacity and potential delays in mixed-traffic areas, they are still an effective alternative to other forms of public transport. LRT features potential to address local transportation needs while promoting environmental sustainability and urban development without the high costs of heavy rail infrastructure
The Development and Impact of Rubber-Tyred Metro Systems in Urban Transport
A rubber-tyred metro is a type of rapid transit system that incorporates both road and rail technology. These trains are equipped with rubber tyres, which provide traction as they run on specially designed pathways supported by guide bars. Additionally, the trains have traditional flanged steel wheels that run on rail tracks. These steel wheels guide the trains through track switches and serve as a safety backup in case of tyre failure. Rubber-tyred metros are typically purpose-built and customized to meet the specific requirements of the transit system they operate on.
Historical Background of Rubber-Tyred Metro Systems
Rubber-tyred metro technology was first introduced on the Paris Metro. It was developed through a collaboration between Michelin, which supplied the tyres and guidance system, and Renault, which provided the vehicles. In 1951, an experimental train called the MP 51 began operating on a test track between Porte des Lilas and Pré Saint Gervais.
First Operations of Rubber Tyred Metro
The rubber-tyred technology was first deployed on Line 11 (Châtelet – Mairie des Lilas) of the Paris Metro in 1956. Subsequently, the other metro lines including Line 1(Château de Vincennes – Pont de Neuilly) in 1964 and Line 4 (Porte d’Orléans – Porte de Clignancourt) were converted in 1967 to adapt to rubber-tyred technology as both these lines carried heavy traffic in Paris Metro. Due to the high cost of converting existing rail-based lines such conversions are no longer carried out. Instead, Rubber-Tyred metros are now launched for new systems and lines.
First Complete Rubber-Tyred Metro System
- The first completely rubber-tyred metro system was introduced in Montreal, Quebec, Canada, in 1966.
Automated Rubber-Tyred Metro System
- The first automated rubber-tyred metro system began operations in Kobe, Japan, in February 1981
Vehicle and Power Supply
In a rubber-tyred metro system, vehicles are typically electric multiple units (EMU) which are powered by a guiding bar which serves as a third rail system.
Power Supply and Current Flow
- Power Supply: The vehicles are powered through the guide bars, with current picked up via a lateral pickup shoe.
- Return Current: The return current is directed through a return shoe which sends current to the top of one or both rails or to the other guide bar.
Types of Guideways
The type of guideway used can vary across systems. Common guideways include:
- Concrete Rollways: These are typically two parallel concrete rollways, each the width of a tyre. This design is used in systems such as the Montreal Metro, Lille Metro, Toulouse Metro and Santiago Metro.
- H-shaped Hot-Rolled Steel: This design is used particularly in the Paris Metro, Mexico City Metro and non-underground sections of the Santiago Metro.
Guidance and Steering
- Steel Wheels on Steel Tracks: Like traditional railways, rubber-tyred metro systems use redundant steel wheels with flanges on steel tracks for guidance.
Advantages
- Smooth Ride Quality: Rubber tyres provide a smoother ride by absorbing shocks and vibrations.
- Adaptability to Steep Gradients: Rubber-tyred metros can navigate steeper slopes (up to 13% gradient which makes them suitable for cities with critical topographies.
- Reduced Noise Levels: The operation of rubber-tyred metros tends to be quieter than that of steel-wheeled systems.
- Lower Rail Wear: Rubber tyres cause less wear on the tracks compared to steel wheels which reduces maintenance costs for rail infrastructure.
Disadvantages
- Higher Energy Consumption: Rubber-tyred metros generally consume more energy than their steel counterparts due to increased rolling resistance and friction between the tyres and the guideway. This also increases the operational costs.
- Higher Initial Costs: The construction and installation of rubber-tyred metro systems are more expensive due to the need for specialised guideways and dual-wheel designs.
- Frequent tyre Replacement: Rubber tyres wear out more quickly than steel wheels which results in more frequent replacements. This not only increases maintenance costs but also contributes to environmental waste from discarded tyres.
Conclusion
The rubber-tyred metro systems offer a range of benefits over traditional steel-wheeled metros, including smoother rides, quieter operations, and the ability to navigate steeper gradients. These benefits make them suitable for cities with challenging topographies. However, they come with drawbacks such as higher energy consumption, frequent tyre replacements, and higher initial construction costs. Nevertheless, Rubber-tyred metro systems remain in operation in several cities worldwide, including Montreal, Paris, and Mexico City. As cities continue to seek efficient and sustainable transit options, rubber-tyred metros are likely to remain a viable choice alongside conventional rail systems.
A Comprehensive Overview of Rolling Stock Components
Rolling stock is a critical element of the rail transit system. It refers to the vehicles that move on a railway track, it includes both powered and unpowered vehicles.
Types of Rolling Stock
- Locomotives: A locomotive is a powerful vehicle that pulls or pushes trains along railway tracks. It provides the primary source of propulsion for the train. It is usually powered by either diesel engines or electric motors.
- Passenger Coaches: Passenger coaches are specialised railcars that are designed to carry people from one place to another.
- Freight Wagons: These are used for transporting goods, these come in various designs suited for different types of cargo, including flatcars, boxcars, and tankers.
Components of Rolling Stock
Rolling stock encompasses a wide range of components that are critical for its functionality, safety, and efficiency. Here’s a detailed breakdown of the key components:
1. Car Body: The elementary component of rolling stock, the car body serves as the main structure that accommodates passengers, is designed to meet operational criteria and consists of major elements.
The critical element of the car body:
- Underframes: The primary structure that provides support to the entire car body.
- Side walls /End walls: Provide structural integrity and help in maintaining overall structural length.
2. Car body Fittings: Car body fittings are additional components attached to the car body. They enhance the overall performance of the car body by contributing highly in the structural integrity, security and functionality of the rolling stock. These include doors, windows and interior fittings.
Types of car body fitting:
- Structural fitting: Provides lateral support through side frames while end frames are designed with the aim of resisting the loads and impacts.
- Joining Fitting: The joining fittings connect the various panels and frames of the rolling stock together through welding flanges.
- Support fitting: The support fitting forms the underframe of the car body through various components like sole bars and cross beams supporting the floor of the rolling stock.
3. Guidance System: The critical component of rolling stock, the guidance system ensures the efficient and safe operations of the train by navigating the tracks.
Components of guidance system:
- Bogies: Bogies, a wheeled frame that supports the railcard body and allows smooth navigation over both straight and curved tracks.
- Key elements include:
- Wheels: Provide contact with the track.
- Axles: Connect the wheels and facilitate rotation.
- Suspension Systems: Absorb shocks from track irregularities.
4. Power system: The power system in rolling stock provides the energy required for the functioning and operation of trains. The system comprises various elements,which ensure the systematic distribution of energy all over the train.
Elements of the power system
- Traction Control Unit (TCU): It manages power distribution to traction motors.
- Power converter: The power converter ensures that an accurate voltage of energy is supplied to each part of the train by managing the conversion of electrical power from one to another.
- Auxiliary Power Systems: Auxiliary systems supply power for non-propulsion functions like lighting, heating, ventilation, air conditioning (HVAC), and passenger information systems.
- Energy Storage Systems: During braking an excessive amount of energy is generated. The energy storage systems like batteries and supercapacitors store this excessive energy for later use.
5. Propulsion System:
- Traction Motor: The traction motor converts the electrical energy into mechanical energy for the functioning of the wheels of the trains.
- Gearbox: It transmits power from the motors to the wheels.
6. Auxiliary system: Auxiliary systems are designed to supply power for the non propulsion functions like (HVAC), lighting, and passenger information systems, necessary for efficient management of operations and passenger convenience.
Components of Auxiliary System
- Auxiliary Power Unit (APU) : Through APU’s the energy generated for the non propulsion functions gets converted from high voltage electricity to low voltage ensuring a systematic power supply for various onboard systems.
- Static Inverters: the static inverters convert the Direct Current ( DC) power to Alternating Current (AC) from the main power supply ensuring frequency outputs.
- Cooling and heating systems: The auxiliary systems comprise HVAC units to ensure the accurate temperature of trains within coaches for passengers. The system facilitates the functioning and operation of fans, compressors and various heating elements.
- Lighting system: the lighting system of the train relies on an auxiliary system. The energy generated by the auxiliary system powers the interior and exterior lighting on trains ensuring efficient operation.
- Passenger Information Systems: The passengers information system provides passengers with the real time updates about the train and journey.
- Control system: To ensure the effective functioning of the auxiliary system, the Control system manages the operation of auxiliary components by monitoring the power consumption and adjusts outputs if required.
7. Door System
The door system in rolling stock refers to the mechanisms and controls that are employed for the opening and closing of train doors.
Types of Train Doors
- Manually Operated Doors: These doors are opened and closed by passenger or train crew.
- Automatic Sliding Doors: Automatic sliding doors are essential components of rolling stock; they are most commonly used in metros.
Configurations of Sliding Doors
- Single-Panel Sliding Doors
- Double (Bi-Parting) Sliding Doors
- Sliding Plug Doors: In this door system the door leaf moves perpendicular to the train body, “unplugging” from the door frame to clear the seal. After unplugging, the door slides parallel to the car body to open.
Configurations of sliding plug doors
- Single Panel
- Double Panel
7. Braking system: A railway braking system refers to the set of components and mechanisms used to slow down or stop a train safely. When a braking force is applied to stop a train, the force must be transmitted to something other than the cars themselves, such as the rails. There are two main methods to achieve this: adhesion braking and non-adhesion braking.
- Adhesion Braking: Relies on friction between the train’s wheels and the rails to slow down the train.
- Non-Adhesion Braking: Non-adhesion braking methods do not rely on friction at the wheel-rail interface. These systems include air resistance.
Types of Braking System
- Mechanical Braking Systems: Mechanical braking systems rely on friction-based components, such as brake shoes and discs, to reduce the train’s speed.
Types of Mechanical Brakes:
- Wheel-Tread Brakes: The brake shoe applies friction directly to the wheel tread to slow the train.
- Axle-Mounted Disc Brakes: These brakes are mounted on the axle of the train and are used in systems like trailer bogies (the non-motorized part of a train).
- Wheel-Mounted Disc Brakes: These are mounted directly on the wheel, often in motor bogies (the motorized part of the train).
- Electric Brake Systems: In electrical braking systems, the braking force is transmitted to the wheels through gears. The traction motor (acting as a generator) generates electricity, which is then used to adjust the braking force.
- Dynamic Braking: In dynamic braking, the train’s traction motor acts as a generator during braking. The kinetic energy of the train is converted into electricity, which is dissipated as heat through a main resistor.
- Regenerative Braking: This is similar to dynamic breaking but instead of dissipating the electricity as heat, the generated electricity is fed back into the overhead wire.
- Pneumatic Brakes: This breaking method uses compressed air to apply pressure to the brake components. This system is widely used in railway transport due to its reliability, ease of control, and ability to apply braking force to all parts of the train simultaneously. Types of Pneumatic Brake Systems include:
- Direct Air Brake: This is a simple system where the release of air directly applies the brakes to the train’s wheels.
- Automatic Air Brake (Westinghouse Brake): This system automatically applies the brakes when air pressure drops.
- Electropneumatic Brakes: This system combines electronic control with pneumatic braking, which ensures quicker and more synchronized braking across multiple carriages.
8. Pantograph: The pantograph is a spring-loaded device on the train’s roof that maintains consistent contact with the overhead wire it ensures uninterrupted current collection.
Types of Pantograph
- Single-Arm Pantographs
- Double-Arm Pantographs
9. Coupler System:
A coupler, or coupling, is a mechanism that connects rail vehicles to form a train.
Types of Coupler
- Manual Couplers
- Semi-Automatic Couplers
- Automatic Couplers
10. Suspension System in Rolling Stock: The suspension system is a critical component of rolling stock. It is designed to absorb and mitigate vibrations and shocks generated by the interaction between the wheels and railway tracks.
Types of Suspension in Rolling Stock
- Primary Suspension: It is Positioned between the wheelset and the bogie. It improves lateral stability by controlling vertical and lateral forces directly from the track.
- Secondary Suspension: It is located between the bogie and the car body. It isolates the carbody from vibrations transmitted via the bogie.
Conclusion
Rolling stock is an essential component of the railway system It consists of locomotives, passenger coaches, and freight wagons. It is made up of various systems, including the power, suspension, guidance, and braking systems, each contributing to the safe and efficient operation of trains. Components like doors, pantographs, and couplers play important roles in passenger convenience. The technological advancements are further strengthening the evolution of rolling stock to improve performance, reduce maintenance, and ensure reliability. Overall, it remains a fundamental aspect of the railway infrastructure, supporting both passenger and freight transport.
