Space weather expert Dr Tamitha Skov tweeted: “New region 3058 fires a M2.9-flare! It is now the fourth region on the Sun with the X-factor.” The US National Oceanic and Atmospheric Administration (NOAA), she added, “set X-flare risk at 10 percent, but that could rise soon”. Flares are grouped into five categories — A, B, C, M and then X, the strongest — and then given a number denoting the size of the phenomena. Dr Skov added: “More radio blackouts impact amateur radio operations on Earth’s dayside are likely. GPS users stay vigilant near dawn and dusk.”
According to a new study, however, space weather events could be upsetting more than GPS and radio communications.
Physicist Cameron Patterson of Lancaster University explains: “Most of us have at one point heard the dreaded words: ‘your train is delayed due to a signalling failure’.
“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.”
The electric currents induced by space weather, he explained, can interfere with the normal operation of signalling systems — turning green signals red when there is no train nearby.
In railway networks, the location of trains are tracked by splitting the lines up into small, consecutive segments known as “blocks” that tend to be 0.6–1.2 miles long.
Each block is tied to a signal which flags whether or not a train is currently in that block.
The signals themselves are controlled by relays which detect currents in the system — with the lights turning green if the block is empty and a current is detected, or red if the block is occupied by a train and no current is detected as a result.
By inducing currents in the railway network, solar storms can cause sections of track to be assigned a red light even when not occupied.
Furthermore, the stronger the solar storm, the more signals are likely to malfunction — increasing the resulting delays experienced by travellers on the railway network.
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In their study, Mr Patterson and his colleagues investigated the impacts of solar storms on two segments of the UK’s railway network — a line running north-south between Lancaster and Preston, and a route that runs east–west between Edinburgh and Glasgow.
Previous studies, the researchers noted, have detected induced currents with field strengths exceeding 7 V/km — while extreme solar storms are expected to produce fields as strong as 20 V/km.
However, solar storms do not need to be this intense to cause signalling failures.
The team found that malfunctions can be induced by solar storms of a range of intensities — from medium storms with electric field strengths of 2V/km to strong storms at 4V/Km.
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With their initial study complete, the team are now considering more extreme outcomes.
Mr Patterson said: “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.”
This, he added, is “a far more hazardous scenario potentially leading to crashes!”
The full findings of the study were presented yesterday at the National Astronomy Meeting (NAM 2022), which is being held from July 11–15 at the University of Warwick.