The road is blocked after a crash near the A15 Riseholme roundabout on Thursday morning.
Lincolnshire Police said the crash on the A15 Ermine Street involved two vehicles and was reported to them at 9.48am on Thursday, June 20.
It could cause delays for anyone heading to the Lincolnshire Show. The B1398 or A46 and Grange de Lings are possible diversion routes.
AA Traffic is reporting slight delays on the A46 Northbound between A57 Saxilby Road (Carholme Roundabout) and A15 Riseholme Roundabout.
The extent of any injuries are not yet known at the time of writing