Rail passengers have been warned of delays and cancellations until the end of New Year’s Eve after 656ft (200m) of signalling cables were stolen in South Yorkshire.
Several routes have been affected following the copper theft between Doncaster and Sheffield, which Network Rail said it was alerted to at about 04:00 GMT.
A spokesperson said engineers had been working on repairs to keep trains moving but passengers were advised disruption was expected until the end of the day.
Network Rail said the theft had so far caused 13 train cancellations with 83 trains delayed by a total of 15 hours and 39 minutes.
Services run by Northern, including local services in South Yorkshire and trains running from Doncaster to Hull and Scarborough, are among those affected.
CrossCountry services between Edinburgh and Birmingham New Street, which call at Sheffield, Wakefield, Leeds and York, have also been affected.
TransPennine Express services running between Liverpool Lime Street and Cleethorpes, which call at Doncaster, have been hit as well.
A spokesperson for Northern said services were able to run between Doncaster and Swinton again from about 09:30 GMT onwards, although they warned that “fewer trains will be able to operate along this route while this issue continues”.
They also said that trains between Sheffield and Doncaster/Adwick “may be delayed or revised”.
“Northern train ticket restrictions have been lifted in the affected areas, including advance and peak restrictions, during this disruption,” they added.
A National Rail spokesperson said: “Theft of signalling cables between Doncaster and Sheffield means trains must run at a reduced speed on all lines.
“As a result, services operating between Doncaster and Sheffield may be cancelled, delayed by up to 25 minutes, revised or diverted.”
A Network Rail spokesperson said further repairs would take place by engineers after the last passenger service.
They added: “Cable theft like this is not only disruptive to passenger and freight services but also costs the taxpayer millions of pounds a year.
“It’s extremely dangerous – with thousands of volts of electricity running through cables, posing fatal risks to perpetrators.
“We work proactively to install new ways of securing cable and we work closely with British Transport Police to trace those responsible for theft.”