Hundreds of rail passengers were left stranded in Peterborough overnight as icicles caused overhead power cables to fail.
East Coast mainline cancelled all services through Peterborough on Sunday afternoon.
The train company said it was due to an overhead power line problem between Stevenage and Peterborough.
There were not enough replacement buses, meaning hundreds of passengers had to spend the night in hotels.
Passengers talking to the BBC described it as "utter utter chaos" and "absolutely horrendous".
The line re-opened on Monday morning and a limited service is running.
A spokesman for National Express East Anglia said icicles were forming under bridges and making contact with overhead power lines causing them to fail.
A Network Rail statement said patrol teams were removing icicles and engineers are at principal stations to attend to defective trains.