Wellington motorists are facing a painful commute into the city as yesterday's rockfall on Ngauranga Gorge causes delays stretching 10km back to Tawa.

Two lanes of the gorge have reopened after a section of hillside collapsed over the main highway into the capital yesterday. Contractors worked through the night to start clearing two of the three lanes.

But motorists are still facing lengthy delays, with a speed limit of 50km/h on the gorge highway, on a bitterly cold day.

NZTA's Mark Owen says people should be patient and consider taking public transport if they haven't left for work already.


He says people should not rubber-neck as they come down the gorge.

Owen says drivers won't be able to see much of the slip as they travel down they road so they should keep their eyes straight ahead.

Meanwhile, Interislander ferry sailings have already been cancelled from Wednesday night until at least Friday because of predicted 7m waves. The Wellington region is expected to cop heavy rain, gale-force winds and snow down to 400m today.

Traffic ground to a halt on the busy motorway when debris scattered across all southbound lanes of the urban gorge.

Contractors worked overnight to clear the highway and stabilise the crumbling hillside.

The New Zealand Transport Agency (NZTA) reopened two of the three affected lanes at 6am ahead of the breakfast rush hour.

Ohariu MP Peter Dunne said the travel chaos caused by the Ngauranga Gorge slips highlights how vulnerable Wellington's transport network is.

Dunne said yesterday wasn't a major disaster but still caused "massive disruption".


He said the slip reinforced the need for Transmission Gully, but also the need for other arterial roads to facilitate access to the city in the event of a major tragedy.

- Additional reporting: Newstalk ZB