A new study has found a slightly worrying problem with the rail network in the UK; its vulnerability to space weather.
Solar storms are a pretty common occurrence – a moderate storm took place last week, for example, after a large hole opened up on the Sun's surface. There's nothing the Sun loves more than being hot and flinging plasma in our direction.
The storms are generally nothing to worry about, unless you are particularly averse to looking at the beauty of the northern lights, or minor problems with power grids, and radio communication.
A team from Lancaster University, UK, attempted to discover how geomagnetic storms could interfere with electricity transmission and distribution grids. Of particular concern was signaling, as there are more than 50,000 signaling track circuits in the UK, where rail signals are carried by an electric circuit.
"Disruption to railway signaling can happen when geomagnetic disturbances induce electric currents in the rails that interfere with the electrical circuits used to detect trains," the team explains in their paper.
"Crucially, our research suggests that space weather is able to flip a signal in either direction, turning a red signal green or a green signal red," physics PhD researcher Cameron Patterson added in a statement. "This is obviously very significant from a safety perspective."
The team found that "wrong side" failures – particularly dangerous as it turns a red signal to a green – occurred at lower geoelectric field thresholds than "right side" failures, where a green signal is turned red. However, the conditions that cause "right side" are less complicated, so the team was unable to determine which error is more common during moderate geomagnetic storms.
“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," Patterson added.
Larger 1-in-100-year storms, like the Carrington Event, would cause widespread problems on the lines studied by the team. Unfortunately, these storms look like they occur more frequently than we thought.
"It is also important to point out that in the event of severe space weather, railway signaling will not be the only system affected," the team adds. "Power supply networks, communications, Global Navigation Satellite Systems (GNSS) are all susceptible, many of which will also impact the safe and smooth operation of the railway network, regardless of the countless affects to other areas."
The team proposes conducting real-world tests to confirm the models, placing equipment along the track to monitor the effect of solar storms.
The study is published in the journal Space Weather.