Rail services to and from London Euston have resumed following emergency repairs but passengers have been told to expect continued disruption.
All lines from the station were closed on Sunday morning as engineers worked to replace downed electrical overhead wires.
Trains began running at around midday, with lines fully open by 1pm, but Network Rail warned services could be delayed throughout the day.
Passengers on trains operated by Virgin, London Midlands and London Overground have been advised to check for disruption before travelling.
Network Rail said: “All railway lines leaving London Euston have been successfully reopened today and trains are now running to and from the station again.
“However services may still be impacted today so passengers are being advised to check before they travel using National Rail Enquiries.”
Customers had earlier been urged not to travel due to the works.
More than 500m of wires near Wembley, north London, needed replacing after they were damaged at around 3.30pm on Friday.
A set of railway points – the sections of tracks which move to allow a train to pass onto another set of rails – also had to be repaired. The cause of the damage is not yet known.
The Rail, Maritime and Transport union (RMT) called for an investigation into maintenance cuts on the railways.
General secretary Mick Cash said “serious questions” needed to be asked about the state of rail infrastructure in Britain.
He said: “The Government should be praising the staff out there today working to get services running, rather than threatening them with more cuts and privatisation.
“RMT is demanding an investigation into the impact of current cuts to maintenance and renewals at Network Rail and the future impact of the further planned cuts, privatisation and fragmentation that we know the Government have lined up.
“Those cuts should be halted and reversed if we are to avoid repeated breakdowns and failures.
“If the profits bled out of the rail network by the rip-off private rail companies were reinvested in staffing and infrastructure we could build a railway genuinely fit for the modern age.”
Passengers can check if their service is affected at nationalrail.co.uk