State Highway 1/Main South Road is closed near Selwyn Lake Road, following a single-vehicle crash about 7.30pm.
The crash involved a car colliding with a signal box at the train tracks and the barrier arms are stuck in the down position, blocking the road.
There are no reports of injuries.
The road is expected to be closed for some time.
Police are asking motorists to avoid the area, or expect delays. Drivers can check the latest roading conditions at https://www.journeys.nzta.govt.nz/
ENDS
Issued by Police Media Centre