Solar storms 'could cause rail accidents'

New research from Lancaster University examining the impact of space weather argues that rail accidents could be triggered by solar storms switching signals from red to green.

Solar storms can trigger powerful magnetic disturbances on Earth, and geomagnetically induced currents (GICs) could potentially interfere with electricity and distribution.

PhD researcher Cameron Patterson and Professor Jim Wild modelled how GICs flowed through the track circuits of AC electrified lines powered with overhead cables. They looked at the Preston to Lancaster section of the West Coast Main Line, and the Glasgow to Edinburgh line, analysed how GICs in the rails could cause signalling systems to malfunction. 

“Crucially, our research suggests that space weather is able to flip a signal in either direction, turning a red signal green or a green signal red.  This is obviously very significant from a safety perspective," said Patterson.

“By building a computer model of the signalling track circuits using realistic specifications for the various components of the system, we found that space weather events capable of triggering faults in these track circuits are expected in the UK every few decades.”

Previous research has shown that these "wrong side" failures, which are much more dangerous than when the signal goes from green to red, could occur at lower geoelectric field strengths, and so could be triggered by weaker storms. It's estimated that these wrong side failures could happen every one or two decades, while Patterson also explored a once in a century event and found that it could cause many malfunctions in both directions of travel. 

Patterson said: “When we experience severe space weather which happens every few decades or extreme space weather seen every century or two, then there is a potential for significant signalling misoperation, which has an obvious safety impact.

“Our research shows that space weather poses a serious, if relatively rare, risk to the rail signalling system, which could cause delays or even have more critical, safety implications.  This natural hazard needs to be taken seriously.  By their nature, high-impact, low-frequency events are hard to plan for, but ignoring them is rarely the best way forward.

Jim Wild, Professor of Space Physics at Lancaster University, said: “Other industries such as aviation, electricity generation and transmission, and the space sector are considering the risks to their operations, and exploring how these might be mitigated. It’s important that the rail sector is included in this planning.

“As our understanding of the space weather hazard improves, it’s possible to consider how to reduce the risks. In future, we could see space weather forecasting being used to make decisions about limiting railway operations if an extreme event is expected, just as meteorological forecasts are used currently."