Train services at London Euston are facing disruption on Wednesday after overhead wires were damaged between the station and Watford Junction.
Avanti West Coast and Northwestern Railway services may be delayed or altered but the lines have now reopened, National Rail said.
Avanti West Coast services and London Northwestern Railway services are affected.
Meanwhile the Bakerloo line and London Overground are partly closed and there are delays on the Metropolitan line.
See our latest updates below
Minor delays to Central line
16:13 , Miriam Burrell
There ae minor delays between Leytonstone and Hainault via Newbury Park due to train cancellations.
There is a good service on the rest of the line.
Minor delays on Metropolitan line
15:59 , Miriam Burrell
There are minor delays on the Metropolitan line between Harrow-on-the-Hill and Watford due to train cancellations.
There is a good service on the rest of the line.
Damage to overhead wires has ended
15:58 , Miriam Burrell
Disruption caused by damage to the overhead wires between London Euston and Watford Junction has now ended.
But Avanti West Coast warned passengers they may still face delays on Wednesday afternoon.
M25 delays
12:39 , Michael Howie
The major roads in and around London are largely clear, according to traffic monitor Inrix.
However it is currently reporting severe delays due to emergency repairs on the M25 clockwise at J28 A12 (Brentwood / Brook Street Roundabout).
There is a congestion a couple of miles either side of the M25.
Tube line and Overground partially closed
12:35 , Michael Howie
There is no service on the Bakerloo line between Queens Park and Harrow & Wealdstone, while no Overground trains are running between Euston and Watford Junction.
Disruption at London Euston expected until 2pm
11:48 , Miriam Burrell
Damage to the overhead wires between London Euston and Watford Junction means some lines are blocked.
Trains running between these stations may be cancelled, revised or delayed by up to 30 minutes, National Rail said.