Rail replacement buses after fault with signalling system at Horsham disrupts all rail lines towards London

Southern and Thameslink services from Horsham towards Three Bridges, Gatwick Airport and London are expected to be delayed.

Trains from Horsham to Dorking, are not affected by this incident and passengers will not need an alternative route.

Trains from Horsham towards Bognor Regis and Barnham, are not affected by this incident at present – but these trains will not start from London Victoria.

Southern said the disruption is expected until 6.30pm.

A statement on Southern’s website said: “A track circuit failure is disrupting trains from Horsham towards London.

“This part of the network uses track circuits to detect the position of trains. These are electrical systems which monitor whether a train is on a section of track. They operate as part of the signalling system, which is designed to be "fail safe".

“When a track circuit fails, the signalling system will interpret this as a train remaining in place, even though there may not be a train present at all, or the previous service may have long since left the area.

“As a result, further trains cannot be automatically allowed onto the relevant section of track. Train drivers will be stopped by red signals on approach. They will then get verbal permission from the signaller so that they can proceed, and will run at a heavily-reduced speed as far as the next signal. This is so that the drivers will stop safely if they see anything ahead of them.

“In some areas, the sections between signals can be several miles long, so this can result in delays building up. Even with shorter sections of track affected, there would still be a delay of at least a few minutes to each journey.

“Track circuit faults can be caused by a number of different issues, including electronic faults or obstructions on the track. Network Rail manage the signalling system, including track circuits, and their staff will be investigating as quickly as possible.”

Southern said on X at 5.50pm: “The below stations will not be served in either direction and you will need an alternative route to travel to Horsham or Dorking. If your station is unmanned, please use the station help point to speak to staff who will arrange alternative transport. Rail replacement buses have been requested."

The stations are Holmwood, Ockley and Warnham.

Southern added: "Trains that run from Bognor Regis/Barnham to London Victoria via Horsham can now run as booked but are facing delays of around 30 mins whilst we work to get trains back on time."

UPDATE: At 6.21pm, Southern announced: “Rail replacement buses are now in operation between Horsham and Dorking at the discretion of station staff. These buses will call all stops between these stations so please speak to staff for the best route for you.”