Storms, Signals And Delays: Why Lightning Can Stop Trains Running

Passengers have faced disruption this week after thunderstorms and lightning affected railway signalling systems on parts of the network. On the West Coast Main Line, Network Rail warned passengers after overnight thunderstorms damaged signalling systems, while separate reporting said lightning was believed to have blown fuses in signalling circuits at Weaver Junction, near Runcorn. National Rail also said disruption between Leeds and Carlisle was caused by lightning damaging the signalling system, with the affected section referred to in updates as between Skipton and Carlisle.

To passengers, this can be hard to understand. A storm may pass quickly, the rain may ease, and the skies may clear, yet trains can still be delayed or cancelled for hours afterwards. The reason is that the railway is not only dealing with the weather itself. It is dealing with the effect that lightning, electrical surges, power interruptions and damaged equipment can have on the systems that tell trains when and where it is safe to move.

Signalling is one of the most safety-critical parts of the railway. Signals, track circuits, axle counters, points, power supplies, cables and control systems all work together to prove that a route is clear and correctly set before a train is allowed to proceed. If that system cannot confirm the railway ahead is safe, the railway does not simply guess. It stops trains, slows them down, or introduces manual working until the fault is understood and repaired.

That is why a lightning strike can have consequences far beyond the moment of impact. Lightning does not always need to hit a signal directly to cause problems. Electrical surges can travel through cables, power supplies, communications equipment and other connected systems. A strike can damage sensitive electronic equipment, trip circuits, affect power supplies or cause the signalling system to lose the information it needs to operate normally. Once that happens, the safest response is disruption.

The phrase passengers usually see is “a fault with the signalling system”. That wording is accurate, but it can hide a lot of complexity. A signal fault caused by lightning is not always a simple reset. Engineers may need to inspect equipment, test circuits, confirm that signals and points are responding correctly, and make sure the system is safe before trains can return to normal speeds. Even after the original fault is fixed, trains and crews may be out of position, meaning disruption can continue while the timetable recovers.

The Settle–Carlisle route shows why rural and exposed railways can be especially vulnerable. Lines through open countryside, upland areas and remote terrain may have signalling equipment, communications masts, power supplies and cables spread across difficult locations. If equipment is damaged in a storm, it is not always a case of an engineer stepping out of a nearby depot and replacing a part within minutes. Access can take time, and the geography of the railway can make recovery slower.

The West Coast Main Line shows the other side of the problem. On a busy intercity route, even a relatively localised signalling failure can quickly have a wider effect because so many trains depend on the line. Avanti West Coast, London Northwestern Railway, TransPennine Express, freight services and other operators can all be affected by problems on key sections of the route. When signals fail, the railway may have to reduce capacity, hold trains back, divert services or cancel journeys to prevent the network becoming unmanageable.

It is important to say that this is not the railway being overcautious for the sake of it. Signalling systems are designed to fail safe. If something goes wrong, the default position is to stop trains rather than allow them to continue on incomplete or unreliable information. That can be deeply frustrating for passengers, but it is the principle that prevents a technical fault from becoming a safety incident.

There is still a fair question about resilience. Lightning is not new, and neither are thunderstorms. Passengers are entitled to ask whether enough is being done to protect signalling equipment, power supplies and communication systems from electrical surges, especially as severe weather creates repeated pressure on the network. Surge protection, remote monitoring, backup power, modernised signalling and quicker fault detection can all help, but the impact of weather on the railway shows how important resilience has become.

The problem is that Britain’s railway is a vast mix of old and new infrastructure. Modern electronic signalling may offer more capability, but it can also depend on sensitive equipment, power supplies, data links and communications networks. Older routes may have legacy systems that are robust in some ways but difficult to repair quickly when faults occur. Either way, when lightning damages the system that proves trains can move safely, the railway has limited options.

For passengers, the most visible result is delay. For engineers and signallers, the situation is far more technical. They have to identify what has failed, check whether related equipment has also been affected, restore power or communications where needed, and then test the system before normal working resumes. If the fault affects points, signals or track detection, trains may only be able to move under special instructions, at reduced speed, or not at all until repairs are complete.

The railway cannot stop thunderstorms, and it should never override safety systems just to keep trains moving. But it does need to explain these incidents more clearly. “Signalling fault” may be technically correct, but when the cause is lightning damage, passengers deserve to understand why a brief storm can lead to hours of disruption. The more clearly the railway explains the chain of events, the easier it is for passengers to see that these delays are not just excuses, but the result of safety-critical systems doing what they are designed to do.

Lightning disruption is frustrating, but it is also a reminder of how dependent the railway is on invisible systems working correctly. A train can be ready, the driver can be in the cab, and the track can look clear to the naked eye. But if the signalling system cannot prove that the route ahead is safe, the railway has to stop. That is why lightning can bring trains to a halt long after the thunder has faded — and why resilience against severe weather is now one of the biggest challenges facing the network.