People are being urged to avoid State Highway 1 north of Wellington as traffic has backed up after a major gas leak.
The stretch of road between Mackays Crossing and Paekakariki has reopened after being closed in both directions since about 11.30am.
The Fire Service and police have been at the scene.
The New Zealand Transport Agency (NZTA) warned motorists to expect delays, with significant traffic backed up in both directions.
Drivers with destinations north of Kapiti were urged to consider using SH2 as an alternative route.
But NZTA regional transport response team chair Richard Hocken said people in Wellington should delay their trip home.
"Have tea in town, go see a movie then go and head home."
Traffic remained backed up to the Paramata Bridge, nearly 20km south about 5.30pm.
Gas company First Gas said a repair job at the Paekakariki North Mainline Valve Station saw gas vent to the atmosphere about 10pm.
The company said there were no immediate safety concerns and gas supplies to Wellington and the lower North Island would not be affected, but the road was closed as a precautionary measure.
The company expected the repair to be completed by 4pm this afternoon.