Extreme solar storms could cause train crashes, scientists warn

Even moderate space weather can cause railway signals to change wrongly

People in front of the sunset (Jacob King/PA) (PA Archive)

Extreme space weather could cause train crashes, new research has warned.

Fluctuations in the Sun could cause solar storms that affect railway signals, according to a scientist.

Space weather describes the way that changes in the conditions on the Sun send material towards us that can affect technology both in space and on the Earth. Changes in that weather can affect satellites, communications technologies and power grids.

Now scientists have warned they could also pose considerable danger to rail networks. Electrical currents that flow in the Earth because of activity on the Sun can alter the operation of railway signals, scientists have warned.

That could mean that green signals could be turned into red ones, they note. That in turn could lead to delays – or worse, the research warns.

“Most of us have at one point heard the dreaded words: ‘your train is delayed due to a signalling failure’, and while we usually connect these faults to rain, snow and leaves on the line, you may not have considered that the Sun can also cause railway signals to malfunction,” said Cameron Patterson, from Lancaster University, who is presenting his research at the National Astronomy Meeting this week.

Each railway line is split into “blocks”, which are a kilometre or two long, and trains are tracked as they go through them. Other drivers are then alerted to whether those blocks are occupied or not, using signals controlled by relays that use electrical currents.

But solar storms can disrupt that process. Lights will show as occupied with a red light, even when no train is there – and the more extreme the storm, the more blocks can be affected.

Even relatively moderate storms can cause those problems, the results show. And extreme storms could cause significant issues.

“We are now working on looking at the case where trains are present on the line, and how strong a storm needs to be to turn a red signal back to green – a far more hazardous scenario potentially leading to crashes!” Patterson said in a statement.