Train delays after UK rail network hit by nationwide fault

National Rail said travellers should plan for some services to be cancelled at short notice.

It said the issue appears to be a fault with the onboard GSMR radio system, which is used to communicate in case of emergencies.

According to the Rail Safety and Standards Board Rule Book, in the case of a radio system failure, trains cannot exceed 100mph (160km/h), or 60mph (100km/h) through affected areas.

National Rail said it is investigating the cause of the fault. It advises that passengers may be entitled to compensation if their journey is delayed.

There are delays of around 10-15 minutes are expected on Southern, Thameslink and Great Northern services, with some short notice cancellations possible.

Most passengers on these lines will be able to travel on their normal route, National Rail has said. Disruption is currently expected to continue until 12:00 GMT.

The Gatwick Express is only running between London Victoria and Gatwick Airport, not serving Brighton, while some Heathrow Express trains between Reading and Heathrow Airport are also delayed.

Elizabeth line services on this route are also affected.

Trains from Brighton to Southampton Central will now only be running to Bognor Regis or Chichester. And services between Kings Lynn and London Kings Cross will only run between Kings Lynn and Cambridge.

ScotRail says its services were impacted earlier this morning but are now operating normally.

GSMR works in a similar way to mobile phones, but the digital system is not reliant on commercial mobile phone operators. The rail network has its own contained phone and mast system.

It allows drivers and signallers to communicate in areas – such as tunnels – where previous analogue systems did not work.

One rail source told the BBC that “the system isn’t connecting easily”.

There is a work around that staff can use, but it takes time to implement.