Solar storms could flip signals, risking deadly crashes

solar storms – A new warning from researchers says space weather can disrupt rail signalling by driving unexpected currents through track systems. In the worst scenario, a red signal could turn green, leaving train crews with little time to respond.

On a railway line, a single colour decides whether a train can move. But in rare cases, that colour could be changed from the sky.

Cameron Patterson, a researcher at Lancaster University in the UK, says electrical systems in railways across many countries—including the UK—are vulnerable to space weather. In the worst case, he warns, a red signal could be turned green, potentially enabling a deadly train crash.

Patterson’s concern isn’t theoretical. He says railway signalling systems are crucial to safety. and that disruptions could follow when solar storms disturb Earth’s magnetic field. “You could have disruptions to signalling systems, which are crucial to railway safety,” he says. “We have to prepare for these things now, and getting that message across, I think, is really important.”.

The chain begins with the sun. The sun constantly blasts out charged particles and light. This solar wind is what causes auroras. Sometimes the sun emits more material than usual in what is known as a solar storm, which can affect Earth’s magnetic field.

The main danger is to satellites, Patterson notes. But solar storms can also affect electrical systems on the ground because changes in a magnetic field can induce unexpected currents—including in railway tracks.

That becomes especially dangerous because many railway systems rely on direct currents running through sections of track to detect whether trains are present or absent. When a train passes through, it changes the amount of current flowing. Patterson says that when geomagnetically induced currents are added to the mix. they can create anomalies—signals that should be green can turn red. or the reverse.

There is another pressure point: speed. “You’ve got to remember these trains are going at very high speeds. If they don’t have advance warning, it might be too late to slow down.”

The clearest documented case Patterson can point to is in Sweden in July 1982. when signals switching were linked to geomagnetically induced currents flowing through a track section. Patterson suspects more cases may exist, but engineers may not think space weather is the cause. By the time they reach the scene, the storm is usually over and nothing is found, he says.

In Russia, research has found correlations between solar storms and signalling anomalies.

Red turning green is the most alarming scenario. But Patterson warns that green signals turning red can also trigger serious disruption. If trains get stuck and electrical systems fail, passengers may leave the train, putting themselves in danger.

The risk is “thankfully low,” Patterson says. Solar storms strong enough to cause this kind of signalling issue happen around once every 30 years. Still. he adds a warning that lands differently: “But a 1-in-100-year event might very well happen next month.” Very large storms could cause widespread blackouts. leading to major disruption beyond rail.

Not every signalling system works the same way. Some countries use a different method in which magnetic sensors count the number of passing train wheels. Patterson says it isn’t clear if those systems are vulnerable to geomagnetically induced currents.

Solar storms may also disturb other rail technologies. Patterson lists transformers connected to overhead electric lines, systems used to tilt trains around curves at high speed, radio communications, and satellite navigation systems used for detecting a train’s precise location.

Now Patterson is trying to turn concern into safeguards. He is collaborating with Network Rail, the Rail Safety Standards Board, and engineering companies in the UK to help make systems more resilient. It was hard to get those conversations started, he says, but they are taking it seriously.

Magnus Wik at the Swedish Institute of Space Physics agrees that signalling anomalies due to solar storms may be going undetected. “They may experience a short disturbance and then it is back to normal, and they don’t know what caused it and [have] no evidence of it,” he says.

Wik points to changes made in Sweden after earlier geomagnetic storms. He says Sweden modified its railway system in the 1950s after signals turned from red to green during geomagnetic storms in the 1930s. In the 1982 incident, he says, signals turned from green to red, which he describes as less serious.

Wik adds that Swedish authorities may not know whether the 1982-type switch could occur again or whether similar events happened multiple times. “The Swedish Transport Administration probably don’t know if this can occur again or if it has happened multiple times. ” he says. He says a possible study has been discussed to check for past geomagnetic disturbances and compare them with error logs. but this is not official.

space weather solar storms geomagnetically induced currents rail signalling Network Rail railway safety Lancaster University European Geosciences Union satellite navigation