The A1 in Lincolnshire is closed southbound near to Stamford due to a serious collision.
The closure has been in place throughout the night and is impacting traffic on the morning of Thursday, December 22.
Drivers have found the carriageway blocked between the A607 Harlaxton and the A606 Stamford.
An unplanned emergency closure on the A607 in Melton Mowbray, which would ordinarily make up part of the official diversion route, means drivers are instead being told to take local routes.
Those travelling further afield are being asked to use the M1.