Lines have reopened following the communication alarm being activated on a train at Norwood Junction.
Trains running between Sydenham and West Croydon may still be cancelled, revised or delayed by up to 15 minutes.
Disruption is expected until 20:00.
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.