A slip on State Highway 2 has created a traffic queue stretching all the way between Lower Hutt and Wellington.
The New Zealand Transport Agency (NZTA) is warning drivers to expect significant delays travelling towards Petone from Wellington after a slip caused lane closures.
The left northbound lane on the motorway is closed, and NZTA is warning of queues reaching from the Petone off-ramp back to Wellington's Terrace Tunnel and up Ngauranga Gorge.
Traffic was at a standstill earlier with both lanes closed northbound, but the right lane has since reopened.
Several number 83 bus services, which run between Courtenay Place and Eastbourne, have been cancelled.
By 4.30pm the estimated travel time to get from the Terrace Tunnel to Petone was already 74 minutes.
NZTA is asking drivers to consider taking alternative routes home as rush hour approaches.
"Crews are working to clear the slip but it is likely to significantly impact peak traffic time due to the safety risks involved and the need to get particular equipment to the site," NZTA said in a statement.
Waka Kotahi (NZTA) advises motorists to avoid the area if possible and consider using State Highways 1 and State Highway 58 as alternative routes.
Posts on social media show the queue has now stretched past the Terrace Tunnel into Wellington city.