According to new research, solar storms can trigger powerful magnetic disturbances on Earth, creating geomagnetically induced currents (GICs) that could potentially interfere with electricity transmission and distribution grids — and even cause train accidents with the switching of signalling from red to green.
A team led by PhD researcher Cameron Patterson and Professor Jim Wild from
Lancaster University have modelled how GICs flowed through the track circuits of AC electrified lines powered with overhead cables; and using two routes — the Preston to Lancaster section of the West Coast Main Line, and the Glasgow to Edinburgh line — the team modelled how GICs induced in the rails could cause rail signalling to malfunction; they also highlighted the fact that there are more than 50,000 signalling track circuits in the UK where the signal is controlled by an electrical circuit between the rails.
Mr Patterson said: “Crucially, our research suggests that space weather can flip a signal in either direction, turning a red signal green or a green signal red, a situation that is very significant from a safety perspective. 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.”
Earlier research undertaken by Mr Cameron explored what is known in the industry as ‘right side’ failures, where the signal is switched from green to red; and while this is a fail-safe scenario, the converse of ‘wrong side’ failures — when the signal goes from red to green — are much more hazardous. The latest study shows that ‘wrong side’ failures could occur at a lower geoelectric field strength than for ‘right side’ failures, meaning a weaker geomagnetic storm could more easily trigger ‘wrong side’ failures.
Mr Cameron highlighted the fact that there have been several examples of space weather impacting power grids in the last few decades, including power outages affecting millions across the Canadian province of Quebec in 1989 and the Swedish city of Malmo in 2003.
“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. 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.”
Severe space weather is included in the UK Government’s National Risk Register for Civil Emergencies, which lists the risk posed to the UK’s economy and society as ‘significant’.