How Trains Are Powered on the Railway | Third Rail vs Over Head Line Wires

Summary

This video explores the two primary electrification methods used in railways: the Third Rail and Overhead Line systems. It examines the advantages and disadvantages of each, such as cost, safety, efficiency, and weather resilience. Third rail systems are cheaper and more weather-resistant but come with safety risks and limitations in speed and range. Overhead line systems, on the other hand, offer better efficiency, higher speeds, and greater safety but require higher initial costs and are vulnerable to weather-related disruptions. The video also discusses the broader implications of railway electrification in the context of decarbonisation and energy supply challenges.

Takeaways

• 😀 Electrification of railways is essential for reducing carbon footprints and moving away from carbon-based fossil fuels.
• 🚂 The two main methods of delivering electrical power to trains are overhead lines and third rail systems, each with distinct advantages and disadvantages.
• ⚡ The third rail system uses a rail next to the track that carries electrical power, with a shoe on the train drawing power from it.
• 💰 The third rail system is cheaper and easier to install than overhead lines, requiring fewer new structures and causing less disruption to existing infrastructure.
• 🌬️ Third rail systems are more resilient to weather conditions like high winds and heat, as the power source is grounded and less prone to damage.
• ⚠️ A significant drawback of the third rail system is the safety risk posed by live rails on the ground, especially during maintenance or emergency evacuations.
• 🚫 The third rail system is unsuitable for high-speed rail due to mechanical limitations and efficiency issues over long distances.
• 🏗️ The overhead line system uses suspended electrified wires, which are more efficient for long-distance power transmission and better for high-speed and freight trains.
• 🛠️ Overhead lines require significant upfront investment for infrastructure, including masts and wiring, and can be affected by weather-related challenges like high winds or ice.
• ⚡ Overhead line systems reduce the need for onboard transformers, creating more space for passengers and reducing the weight of trains.
• 🌍 Electrification of railways can be hindered by the reliability of a nation's power grid, and some areas may continue to rely on diesel trains due to cost-effectiveness and operational flexibility.

Q & A

What are the two main methods used for electrifying railways?

The two main methods used for electrifying railways are overhead lines (OLE) and third rail systems. Each method has its own advantages and disadvantages.

What is the primary advantage of the third rail system over overhead lines?

The primary advantage of the third rail system is its lower installation cost. It requires fewer new infrastructure components, like masts, and can be more easily integrated into existing track networks.

Why is the overhead line system preferred for high-speed trains?

The overhead line system is preferred for high-speed trains because it supports higher voltages and can transmit power more efficiently over long distances, allowing trains to run faster and more reliably.

What safety concern does the third rail system pose?

The third rail system poses a significant safety risk because the high-voltage rail is exposed on the ground, which is dangerous for both maintenance workers and the public, especially if people or animals come into contact with it.

How does weather affect the third rail system?

The third rail system is vulnerable to flooding, as the electrified rail is located on the ground. Additionally, ice can build up on the rail during cold weather, disrupting power transmission.

What are the advantages of the overhead line system compared to the third rail?

The advantages of the overhead line system include increased safety, as the electrified elements are suspended above the track, more efficient power transmission over long distances, and suitability for freight trains and high-speed services.

What weather conditions can negatively impact the overhead line system?

The overhead line system can be impacted by high winds, hot weather, and ice. High winds can bring down trees onto the wires, hot weather can cause the wires to sag, and ice buildup can cause disruptions to power transmission.

Why are third rail systems less efficient for long-distance power transmission?

Third rail systems use direct current (DC), which is less efficient than alternating current (AC) for transmitting power over long distances. This inefficiency leads to the need for more substations and trackside equipment.

How does the move towards electrification impact the flexibility of diesel trains?

Diesel trains offer greater flexibility because they can run on both electrified and non-electrified tracks, whereas electric trains rely on the power grid and require infrastructure like overhead lines or third rails.

What are the challenges associated with installing overhead line systems?

Installing overhead line systems is costly and requires structures to suspend the wires at regular intervals. There are also challenges with navigating low bridges, tunnels, and viaducts, which can complicate installation and maintenance.