The A1 northbound is closed between the A52 near Grantham and the B1174 near Gonerby Moor following a serious collision involving a motorcycle.
Lincolnshire Police are attending the scene along with East Midlands Ambulance Service and Lincolnshire & Nottinghamshire Air Ambulance.
A diversion is available:
Follow the route marked with a hollow circle symbol on local road signs:
Exit at Barrowby on to the A52 westbound
Continue to Bingham
At the Saxondale Roundabout take the fourth exit on to the A46 northbound
Follow the A46 northbound to Newark-on-Trent
Re-join the A1 at the Brownhills junction
Note: diversion is 27 miles in length.