The disruption, which began on December 6, 2024, has impacted multiple train lines and is expected to continue until around noon.

Passengers are advised to check for delays, allow extra travel time, and monitor live departure boards, as trains are starting their journeys later than scheduled.

Affected services include the Elizabeth Line, South Western Railway, Gatwick Express, Great Northern, Southern, Southeastern, and Thameslink, with specific routes experiencing cancellations and alterations.

Due to the fault, drivers were required to manually log into the national radio network, a process that typically occurs automatically, leading to further delays.

National Rail has confirmed a nationwide fault affecting the communication system used by train drivers and signallers, leading to significant disruptions across the UK rail network.

The issue was traced to a failed network card that was replaced and fixed by 1 PM on December 5, 2024.

Transport for London reported minor delays as engineers performed emergency repairs, further compounding the travel disruptions.

London Underground and Overground lines also experienced closures and delays on the same day, adding to the overall impact on commuters.

In response to the communication fault, Network Rail is utilizing a manual back-up system to mitigate the impact, which has caused minor delays.

Commuters are advised to seek alternative travel options, such as booking taxis, due to the ongoing delays and cancellations.

Passengers who experience delays of 15-29 minutes are entitled to a quarter of their single ticket price or 12.5% of their return ticket price, while those facing cancellations can return their tickets for a full refund.

Despite the GSM-R system's enhancements for communication, issues such as interference from mobile networks and environmental factors have been identified as potential causes of delays.