The M6 northbound carriageway has been completely shut between junctions 19 and 20 to make emergency repairs to the road surface.
Drivers are currently gridlocked as highway engineers work to fix a number of grid plates that have become loose and lifted out onto the road near the Thelwall Viaduct.
Cheshire police, who are also on the scene, have advised drivers to avoid the M6 northbound in Cheshire as queues have backed up to junction 19 on the M6 at Knutsford and junction 10 of the M56.
The closure is expected to remain in place for several hours, lasting until the evening.
A Cheshire police spokesperson said: "Shortly before 1.00pm today, Thursday 17 August, officers received called to multiple reports of an object in the carriageway on the M6 Northbound, Thelwall Viaduct.
"Officers attended the scene and it was found that a number of grid plates had become loose and lifted out onto the road. Highways engineers are currently in attendance at the site and emergency roadworks are underway."