Recent Thameslink disruption
We would like to sincerely apologise for the disruption to our Thameslink services. We know that these issues have affected our customers multiple times over recent weeks and that you would have had some very difficult journeys.
There has been a recurring issue with the signalling at City Thameslink, and almost all our Thameslink trains, from as far afield as Cambridge, Peterborough, Bedford, Brighton and Rainham, have been affected. These services all pass through City Thameslink, where there are only two tracks, so the impact on trains and passengers has been severe.
We did everything we could to keep people moving, but in order to do that we had to reduce the number of trains running, and that inevitably led to delays and crowding.
The issue isn’t fully resolved yet, but Network Rail engineers are working on a solution in the short-term, before implementing a long-term fix.
If you have been delayed by 15 minutes or more, you may be entitled to compensation. For more information, please visit our Delay Repay webpage.
Below are some FAQs regarding the disruption:
What is causing the problem?
City Thameslink is the location of the alternating current (AC) / direct current (DC) ‘switchover’ – the point at which northbound Thameslink trains stop taking power from the electrified ‘third rail’ in favour of the overhead power lines, and vice versa heading south.
An electrical power problem at City Thameslink has, on multiple days over two weeks, ‘blown’ insulated block joints (IBJs). These IBJs insulate electrical current between sections of track, and track circuits, the critical safety equipment that tells the signalling system where trains are on the network.
On Thursday, another incident occurred in the same location, where several blown fuses had to be replaced.
What are you doing to fix it?
With 130 IBJs along the 1.5 kilometre Thameslink route between London Blackfriars and St Pancras (and the approaches to these stations), simply finding the damaged equipment takes a considerable amount of time. We've been able to find and fix the blown IBJs from the most recent incidents, cleaning the affected area, and adding data loggers to allow us to monitor the area more closely.
We have also fitted some additional equipment known as special end termination units (SEPTUs) to help us protect IBJs and track circuits from power surges and keep trains moving.
We've also moved our response teams, now having them based much closer to City Thameslink, so that they can get to the site more quickly in the event of any future failures.
Are you doing anything else?
We’re doing our best to keep trains moving using the infrastructure we have available to us, but we are also working on a plan to fit ‘axle counters’ as a backup train detection system. That means if a track circuit fails again, we can keep trains moving. That project is currently part-funded, and so we are making the case to Government to install it next year.
What are axle counters?
‘Axle counters’ work by literally counting train axles (wheels) into and out of separate sections of track, helping tell us where trains are on the line. They form a vital part of our signalling systems and when there is a failure, this results in the signals turning red as a failsafe.
Why did it take some time for the customer information to be updated?
When things go wrong on the railway it’s really hard to know what’s happened immediately and advise passengers how long they’ll be delayed. It’s not until an engineer reaches the problem spot, then diagnoses the fault, that it becomes clear. Sometimes it will be a quick fix, at other times it will take longer. This is why sometimes it can be difficult to immediately provide a clear picture of the incident and how disruptive it will be to our services.