Train commuters faced major disruption due to a points failure near London Euston station.
London Northwestern Railway said the issue was caused by “substantial damage” to the railway.
There were delays and cancellations to Avanti West Coast and London Northwestern Railway trains during the Thursday morning peak.
Points are mechanical systems that enable trains to switch from one track to another.
A Network Rail spokesman said its engineers are on site and would fix the problem “as soon as possible”.
Disruption is expected until 10am.
London Euston is the UK’s sixth busiest railway station.
It is used by an average of 126,000 passengers each day, according to Office of Rail and Road data.
Avanti West Coast services were already affected by speed restrictions in Cumbria and north Lancashire due to the wet weather increasing the risk of landslips and flooding.
Trains on a section of the West Coast Main Line between Lancaster and Penrith were restricted to running at 50mph instead of the normal 125mph between 5pm on Wednesday and 10am on Thursday.