Urgent repairs to the track between Gatwick Airport and East Croydon means some lines towards Purley are blocked.
Trains running between these stations may be delayed by up to 10 minutes.
Disruption is expected until 11:30.
Customer Advice
If you are travelling now you can continue to use your planned route, however, please expect delays of up to 10 minutes to your journey.
Planning your journey:
Please check journey planners and station information boards before you travel, and allow extra time to reach your destination.
Live departure boards can be found here and you can check the live map here to see if your journey has been affected.
You can also use the Southern and Thameslink app to find up-to-date travel information.
Can you tell me more about the incident?
We've had a report of a possible issue with the track in this area. Network Rail's engineers are attending as quickly as possible to carry out a detailed inspection.
There are various different types of defects, and the first advice usually comes from drivers or other staff travelling through the area. Response staff will check the location which has been specified and find out whether the track is still supported correctly, whether the rails themselves are in the usual condition, and if there are any problems with the fixings and metalwork which attach the rails to the sleepers.
Until this is done, some trains will be diverted to a different track to avoid the affected area.
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.