We’re very sorry for the disruption faced by customers over the several days from Friday 18 to Monday 21 July. Such serious disruption over multiple days is very rare, but we know how frustrating and inconvenient it is, so we are grateful to all customers for your patience and understanding.
What has caused the disruption on the network in recent days?
We contended with three major signalling failures on our network on Friday 18, Saturday 19 and Monday 21 July.
On Friday evening from around 20:30, a signalling failure at our Rail Operating Centre in Basingstoke prevented us from running trains on the Windsor and Reading side of our suburban network. While the rest of our network was able to run normally, services on these routes were unable to run for the rest of the night. Signalling was restored at around 01:00, with services able to resume on these routes the following morning.
On Saturday morning at 09:30, a signalling failure at London Waterloo station, connected to the Wimbledon Area Signalling Centre, prevented the use of Platforms 1 to 14. This affected long-distance and some suburban services heading south of London. Trains on the Windsor and Reading routes were unaffected by this second incident. Services were subject to significant delays, cancellations and revisions for the rest of the day, with signalling restored at around 21:00.
On Monday morning at around 05:00, another signalling failure at London Waterloo station once again prevented the use of Platforms 1 to 14, affecting the same routes as the incident on Saturday. Given we could only move very few trains in and out of the station, and trains and crew were not in the right place for the morning peak, we issued a ‘do not travel’ message for customers. Signalling was restored at 09:00 on Monday.
As so many trains and crew were out of position, the ‘do not travel’ message remained in place until midday. The restoration of services progressed throughout the day, particularly for suburban routes, and customers were advised to ‘check before you travel’ from 14:30.
Given the significant challenges involved, service recovery was more difficult on the long-distance routes to Weymouth, Portsmouth and Exeter. To protect the service recovery and get trains and crews in the right place for a good service on Tuesday morning, fewer trains than normal operated on Monday evening.
Why do signalling failures cause such disruption?
Signalling is the traffic light system that allows us to move thousands of trains across the network safely.
When a signalling fault occurs, the system automatically enters a safety mode — known as a ‘fail safe’ — which turns all signals red. This is a built-in feature that stops all train movements when the system loses visibility or control over the tracks and helps keep customers safe.
How does disruption at London Waterloo impact the whole network?
London Waterloo is one of the busiest stations in the country. The vast majority of SWR services – around 1,600 on a typical weekday – either start or terminate at the station.
When space is severely limited at London Waterloo, such as on Saturday and Monday, it creates a knock-on effect that spreads disruption to the whole network.
When trains cannot leave or enter London Waterloo, trains might terminate short of the station or not be able to leave the depot at all. The result is that trains and crew are not where they need to be and services cannot run as intended.
Trains and train crews are assigned to carefully planned schedules – called diagrams –accounting for several different services during the day. If one train can’t get into or out of London Waterloo, this can disrupt many services throughout the day.
Train crews must also adhere to safe working hours and require knowledge of the route they are working, so the right crew has to be available for a service to run.
On Saturday and Monday, 14 out of the 24 platforms at the station could not be used, severely limiting the number of services able to run and preventing trains and crew moving around the whole network.
Even once the problem at London Waterloo is resolved, it can take a long time for trains and crews to get back to where they need to be, so the impact often lasts for hours afterwards.
What is being done to stop these signalling failures happening again?
Engineers worked urgently on site to fix the faults and restore the signalling systems as soon as possible so services could resume.
We’ll now be officially reviewing what happened in detail, to understand the root causes, and to ensure we learn the lessons to help prevent such incidents from happening again.
Once again, we’re very sorry for the disruption faced by customers and thank you for your patience and understanding.
