A lorry is stuck under the bridge on the A607 Harlaxton Road in Grantham, causing delays to train services and roads in the area.
The incident was reported to Lincolnshire Police at 2.35pm on Wednesday, October 30. Police are currently at the scene, along with Network Rail.
It is not yet known if anyone has been injured.
There is heavy traffic on the roads surrounding the rail bridge at the time of writing.
LNER said trains now have to run at reduced speed on all lines.
The firm added that services running through Grantham station may be delayed by up to 10 minutes.
This story will be updated as soon as more information is available.