The A1 in Lincolnshire is closed northbound between the A607 and the A52 near Grantham due to a serious collision.
The incident happened in the early hours of this morning (Thursday).
Emergency services including Lincolnshire Police are in attendance. Highways England have also deployed resources to assist.
Road users are advised to expect disruption and to allow extra journey time.
Road users are advised to follow the solid black square diversion symbol on road signs.
Exit the A1 at B1174 Little Ponton.
Continue along the B1174 into Grantham to B1174/A52/A607 Bridge End Road/South Parade junction (Gainsborough Corner), then turn right (east) onto the A52.
Continue along the A52 to A52/B6403 roundabout.
Turn left (east) and continue along the A52 until the A52/A15 Roundabout, then turn left (north) onto the A15 and travel along the A15 through Osbournby village.
Continue straight over the A15/A153 Quarrington Roundabout to the A17/A15 Holdingham Roundabout, and then turn left (west) onto the A17.
Continue for 12km until the A17 Coddington Roundabout, go straight over and continue along A17 to A1/A17/A46 roundabout, then go straight over onto A46 to A46/A1 Brownhills Roundabout.
Turn right (north) at Brownhills to re-join the A1.