How Space Storms Can Disrupt Train Signals and Lead to Serious Accidents

Electrical systems on railways worldwide, including the UK, are vulnerable to solar weather events. In extreme cases, faults in the system could result in a red signal mistakenly displaying green, raising the risk of serious train accidents. Cameron Patterson, an expert from Lancaster University, UK, emphasizes the urgency of addressing this issue.

“Solar storms can disrupt signaling systems, which are essential for railway safety,” Patterson warns. “It’s vital to enhance our preparedness for these phenomena.”

The sun continually emits light along with charged particles known as solar wind, which can create auroras. However, during a solar storm, the sun can release excess material that impacts Earth’s magnetic field.

While satellites are primarily at risk, solar storms also pose threats to ground-based electrical systems. Changes in magnetic fields can generate unintended currents, particularly in railroad tracks.

This phenomenon is problematic since many railway systems depend on direct current flowing through specific track sections to detect train presence. When a train passes by, it alters the current flow.

“Geomagnetically induced currents can create various anomalies, causing signals to misbehave — for instance, a green signal turning red,” Patterson explained at a recent European Geosciences Union meeting in Vienna, Austria. “Trains travel at high speeds; if there’s no warning, it may be too late to stop.”

Remarkably, Patterson is aware of only one documented case of a signal being affected during a solar storm, which occurred in Sweden in July 1982. “They observed the signal altering and correlated it with geomagnetically induced currents on the tracks,” Patterson stated.

He suspects there are numerous instances yet to be identified, as engineers typically overlook space weather as a possible cause. By the time they investigate, the storm has usually diminished, leaving them unable to pinpoint any anomalies. Research in Russia has also found links between solar storms and signaling irregularities.

While a red signal mistakenly turning green presents a significant risk, the reverse — a green light changing to red — can also lead to serious disruptions. In the event of an electrical failure, passengers may have to evacuate a stalled train, which poses additional dangers,” Patterson noted.

Fortunately, the overall risk remains low. Severe solar storms capable of inducing such disruptions are estimated to occur roughly every 30 years. “However, a once-in-a-hundred-year event could happen anytime,” Patterson cautions. Large storms can result in widespread power outages and significant chaos.

Some countries operate on different signaling systems that use magnetic sensors to count train wheels. It’s unclear whether these systems would fall prey to geomagnetically induced currents.

A variety of other rail systems are also susceptible to solar storm-related disruptions, including transformers linked to overhead wires, systems designed for tilting trains on curves, radio communications, and satellite navigation systems that detect a train’s location.

Patterson is currently collaborating with Network Rail, the Railway Safety Standards Board, and a UK engineering firm to enhance system resilience. He notes that starting this dialogue has been challenging, but they’re committed to making meaningful progress.

Magnus Wike, a researcher at the Swedish Institute for Astrophysics, agrees with Patterson regarding the possibility of unnoticed solar storm signals. “There could be temporary disruptions that resolve quickly, leaving us unaware of their cause,” he said.

Wik informed that in the 1950s, Sweden upgraded its railway system after traffic lights switched from red to green during geomagnetic storms in the 1930s. He indicated that the 1982 incident was less serious, involving a switch from green to red.

“The Swedish Transport Agency likely doesn’t know whether these occurrences could happen again or how frequently they might have happened,” he explained. “We have considered researching past geomagnetic disturbances to match them with error logs, but this remains unofficial.”