A truck has rolled, blocking one lane of State Highway 7 - the temporary main road between Picton and Christchurch.
Police are urging motorists to expect delays.
The road is currently down to one lane due to the crash, which happened about 10km south of the Hope River bridge.
Canterbury police have asked motorists to be cautious when using the highway which is going to be the replacement for SH1 for some time due to the Kaikoura earthquakes.
