What a signal failure means
Trains may be delayed due to a fault with a signal in this area. In this case, the signal is unable to show the normal coloured light indications to drivers, which means that your train will need to travel at reduced speed on this part of the network.
Railway signals are designed to warn drivers that they have to stop because the system can’t yet confirm that the route ahead is clear. In most places, the signalling system will show a green light, or aspect, when the track is clear for a long distance ahead, and drivers will then be shown one or two yellow lights to warn them when they are approaching a red signal. This means that they can anticipate the amount of braking that’s required to stop before they reach another train or any form of problem on the line.
Signalling runs on “fail safe” principles, so if the signals can’t step through the usual colours, they will instead show a more restrictive colour – for example, yellow instead of green. This means drivers will be expecting to come to a stop, but in fact, the route ahead may still be clear. This leads to delays whilst trains proceed more slowly than usual.
The signalling system is maintained by Network Rail, and the team are working closely with them to diagnose the fault and make sure it is fixed as quickly as possible. Until this is done, Southern will be closely monitoring the train service and doing their best to keep to the timetable.
