How solar storms affect railway signals

A project investigating the effects of solar storms on railway signals, presented this week at the National Astronomy Meeting (NAM 2022) by Cameron Patterson, a PhD student at Lancaster University, shows how fluctuations in space weather are disrupting train signals and causing significant delays.

• In railways, electric currents caused to flow in the earth by solar activity can interfere with the normal operation of signals, turning green signals to red even when there is no train nearby.

A team of researchers at the University of Lancaster have modeled the impacts of solar storms on two segments of the UK railway network: a South-North line from Preston to Lancaster and a West-East line from Glasgow to Edinburgh.¹

They found that technical problems can occur as a result of solar storms with a range of strengths: from medium storms with electric field strengths of 2V/km to strong storms at 4V/km.

In the past, values of higher than 7 V/km have been detected along railways in Sweden. Estimates of extreme solar storms have predicted events with strengths of up to 20 V/km.

Interestingly, the results suggest that signaling failures can occur even with moderate storms. So, while these estimates are unsettling, there is still cause for concern without these extreme storms.

“Most of us have at one point heard the dreaded words: ‘your train is delayed due to a signaling 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,” Patterson said.

Describing the future of his work, Patterson says: “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!”

References:

¹ Space weather will delay your trains – RAS – July 13, 2022

Featured image credit: NASA