Flooding in the Mill Hill and Elstree areas means that trains have to run at reduced speed on the line between London St Pancras International and St Albans.
As a result, trains running between these stations may be delayed by up to 20 minutes.
Disruption is expected until 18:00.
Customer Advice
Please allow an extra 20 minutes for your journey.
At present, trains which use the 'slow' lines between St Albans and St Pancras need to travel at 5 mph through the affected section of track. This affects Luton to Sutton services.
Planning your journey:
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Can you tell me more about the incident?
Thameslink been advised of flooding affecting the railway in the Mill Hill and Elstree areas.
Your journey is likely to be disrupted, as your train is likely to need to run at a reduced speed through the area. Thameslink are working with Network Rail to ensure that the railway is safe and that trains can run normally.
Network Rail response staff are on site at present investigating the flooding.
Floods can cause a number of problems for railway infrastructure. If water is fast-moving, it can dislodge the ballast which supports the track. Ballast is the term we use for the small granite stones which you see under the rails. As ballast is used to ensure the railway track has a stable base, it's important that it's in a safe condition.
There are also potential issues for the electric third rail which powers many of our trains, as well as the signalling system.
To help reduce disruption caused by flooding, Thameslink work with Network Rail to ensure pumps and flood barriers are in place, and also jointly plan for the impact of severe weather. Control room staff monitor reports of excess water and ensure staff are sent to deal with this is as quickly as possible.
Check before you travel:
You can check your journey using the National Rail Enquiries real-time Journey Planner.
Compensation:
You may be entitled to compensation if you experience a delay in completing your journey today. Please keep your train ticket and make a note of your journey, as both will be required to support any claim.