State Highway 1 is blocked at the Rakaia Bridge in mid-Canterbury, where a crash early this morning left a truck dangling off the side of the bridge.
The police say two people suffered minor injuries when the truck collided with a car in slippery conditions about 6.30am.
Drivers are being asked to avoid the area or use an alternate route until the truck can be removed.
The police say the road is being gritted to make it less slippery.