A fault with the signalling system between Lincoln and Newark is causing major disruption on the train line.
Engineers from Network Rail are on their way to the Newark Flat Crossing, where the problem is believed to have started.
It has caused major disruption for East Midlands Trains on the Leicester, Lincoln and Grimsby route.
They are expecting the line to be fully reopened at 5.30pm, with normal train service expected to resume 30 minutes later.
East Midlands Trains are “struggling” to source replacement bus services, but anyone with journeys delayed by more than half an hour may get compensation.