The A180 eastbound is set to be closed into this afternoon after a crash earlier this morning.
Police and Highways England have shut the road from the junction with the A15 heading towards the Humber Bridge.
The crash is believed to have happened sometime before 6am on Monday, September 4.
There are severe delays eastbound heading towards the road closure, with traffic building back as far back as Brigg.
Motorists should follow the diversions.
The westbound carriageway is not affected by the closure.
The road is estimated to reopen at around 3pm this afternoon.
A spokesman for the Highways Agency said: “The A180 eastbound in Lincolnshire is closed between the junctions with the A180/A15 (near Scunthorpe) and the A160 (South Killingholme) due to an on-going incident. This incident is being led by Humberside Police who will be conducting full collision investigation work.
“It is anticipated that the road closure will be in place for a number of hours throughout this morning and possibly going into this afternoon.”