The bridge over the River Don at Stainforth has been closed by Doncaster Council this afternoon to allow emergency repairs to be carried out.
It is understood a vehicle has collided with one of the bridge's walls at the side of the carriageway rendering it unsafe.
Doncaster Council tweeted that Bridge Hill at Stainforth was closed from Plumtree Hill Road to Water Lane.
The road connects Stainforth with Fishlake and is used by hundreds of drivers a day.
The council's tweet said: "Bridge Hill at Stainforth has been closed for emergency repairs. A diversion is in place. We'll provide further updates when we get them."