Train services between Nottingham and Newark were likely to be suspended all this week while damage caused by a derailment was repaired.
A freight train carrying diesel damaged 1km of track and a level crossing at Stoke Lane in the early hours of Tuesday 27 August.
Network Rail said on Monday that the track repair project had progressed well over the weekend. But significant work to stabilise ground under the crossing where the derailment took place must be done before services can resume.
Services were suspended within hours of Network Rail resuming full services from Nottingham station after a mammoth five-week project to improve track and signalling.
The rail operator spent £100M replacing 1960s infrastructure “to improve the reliability of the train service in the East Midlands”.
A spokesman said the derailment was unrelated to the signalling works and did not happen on new track.
Buses are running in both directions between Lincoln and Nottingham, calling at Newark Northgate and Newark Castle. East Midlands Trains is running extra services in both directions between Lincoln and Newark Northgate.
Network Rail apologised to passengers inconvenienced by the suspension.
A spokesman said: “Engineers are working with the council and a number of utility companies to complete this repair as quickly as possible.”