How Could Heatwaves Impact Rail Travel?

Heavy heatwaves can have significant impacts on rail travel, affecting both track safety and passenger comfort. Welded steel rails, which are subject to ambient temperature fluctuations, are particularly vulnerable. This article explores the ways in which extreme heat can disrupt rail travel and what precautions can be taken to mitigate these issues.

Understanding Rail Expansion and Track Buckling

High temperatures can cause materials, including rails, to expand. Modern continuously-welded rails are typically installed under tension to ensure they remain straight and stable. However, as the temperature increases, the metal expands, reducing this tension. If the temperature rises sufficiently, the rail can buckle sideways, leading to potential derailments. It's worth noting that rail temperatures in direct sunlight can soar well above the ambient air temperature.

The issue of track buckling is not unique to Britain. During the 2008 heatwave in Jasper, Canada, a train derailed when the rails buckled. Despite a small expansion gap being designed for such situations, it was insufficient to cope with the intense heat, leading to a dangerous scenario.

Overhead Wires and Power Supply

Heated overhead wires pose another set of challenges for rail travel. Electric trains rely on these power lines, and as the temperature rises, the wires expand, potentially causing them to sag. If a train passes under these sagging wires, a dangerous short circuit can occur, particularly at the high voltages used in modern rail systems (up to 25,000 volts). The mechanisms designed to ensure the appropriate tension can fail, making proactive maintenance essential to prevent such incidents.

Engine Cooling Systems

Diesel trains are also vulnerable to the effects of extreme heat. When the ambient air temperature exceeds the design specifications, the cooling systems for these engines become less efficient, increasing the likelihood of engine failures. This issue was particularly prominent in British High Speed Trains, which faced significant problems during hot summer months due to inefficient cooling systems. Proper maintenance can help prevent such failures.

The Passenger Perspective

From the passenger’s viewpoint, the discomfort caused by heat can be substantial. Air conditioning systems typically become less effective as temperatures rise, leading to warmer compartments. While this inconvenience is generally tolerable for most passengers, it can pose life-threatening risks for individuals with certain health conditions. Ensuring proper cooling and maintaining efficient air conditioning systems are crucial for passenger comfort and safety.

Conclusion: Mitigation Strategies

To navigate the challenges posed by heatwaves in rail travel, several strategies can be employed. Regular maintenance of cooling systems, tighter monitoring of track conditions, and preemptive checks on overhead wires are essential steps. By taking these measures, rail operators can reduce the risks associated with extreme heat and ensure safe and comfortable journeys for all passengers.