All lines between Gidea Park and Shenfield have been closed since 12.30pm today (January 24).
This is impacting several Greater Anglia and Elizabeth line services while the damage is repaired.
Passengers are facing hour-long delays or cancellations while the repair work is done.
As a result, trains may be cancelled, delayed by up to 60 minutes or revised.
The disruption is not expected to clear until 6pm.
National Rail is urging passengers not to travel on the affected routes as the incident is dealt with.
Passengers are being advised to use the following routes to complete their journeys:
- London Underground via any reasonable route, customers can alight at Liverpool Street for the Central line to Gants Hill
- London Buses via any reasonable route, customers can use bus 496 or 294 from Gidea Park towards Harold Wood
- c2c between London Fenchurch Street and Upminster
- London Overground between Romford and Upminster
