Solar storms could cause train accidents, scientists warn

Space weather could cause rail signals to ‘flip’, potentially sending trains into each other

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Solar storms could cause train accidents, scientists have warned.

Space weather – changes in the atmosphere that include blasts of energy from the Sun – can disrupt everything from communications to power grids. Scientists have repeatedly warned that the Earth faces potentially catastrophic danger from solar storms, which could be powerful enough to bring down much of the infrastructure on which we depend.

Now researchers warn that danger could be enough to cause malfunctioning rail signals, which in turn could lead to train accidents.

Researchers modelled how geomagnetically induced currents from solar storms could cause danger, by looking at two routes: the Preston to Lancaster section of the West Coast Main Line, and the Glasgow to Edinburgh line. Those are just two lines that rely heavily on that rail signal, and there’remore than 50,000 signalling track circuits in the UK, which control the railway signal with an electric circuit.

In the new study, they found that space weather would be able to change those circuits. Models suggest that could happen every few decades, the researchers found.

“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 Cameron Patterson from Lancaster University.

“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.”

Patterson had previously worked on research that suggested solar storms could lead to “right side” failures, where signals turn from green to red. Those are less dangerous, since trains will stay at a stop.

But the new research suggests that they can also happen for “wrong side” failures, that change signals to green. What’s more, they actually require less strength to be flipped, suggesting they could happen with less powerful solar storms.

“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,” said Cameron. “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.”

In 1859, the world was hit by what is known as the ‘Carrington Event’, which was powerful enough to knock telegraph signals offline as well as other disruptions. If that happened today, it would cause widespread disruption – including causing widespread problems on both train lines that were examined in the study.

But there have been more recent, if less powerful, examples of space weather that is powerful enough to hit power grids. In 2003, the Swedish city of Malmo suffered problems from space weather, for instance.

The work is reported in a new study, ‘“Wrong Side” Failures Caused by Geomagnetically Induced Currents in Electrified Railway Signalling Systems in the UK’, published in the journal Space Weather.