Elsewhere, a crash on southbound lanes on Auckland's Harbour Bridge was cleared around 4.15pm following a crash.
A truck ploughed into a van and blocked two lanes - causing south-bound traffic to come to a standstill.
The two vehicles have been cleared from the lanes after the crash, which happened just before 3.30pm. They are being towed away but congestion is still easing on the Northern motorway, which was congested back to Esmonde Rd.
A police spokeswoman said emergency services were called to the crash at 3.27pm.
One person had suffered moderate to minor injuries. A reporter at the scene said traffic was at a standstill at 4.10pm.
The police spokeswoman said the two vehicles were being towed and traffic was flowing around the incident. Delays were still expected, she said.
Meanwhile, traffic is slow in both north and southbound directions on the Northern Motorway. Northbound, traffic is built up between Northcote Rd and Constellation Dr. Approaching the bridge from Esmonde Rd is also causing delays.
On the Southern Motorway, traffic is heavy from the CBD to the Mt Wellington Highway. Traffic is slow northbound from Market Rd to the City Centre and heavy from East Tamaki Rd through to Market Rd.
Bond St through to the Spaghetti Junction is also heavy on the Northwestern Motorway. Northbound is heavy from Great North Rd to Lincoln Rd.
Traffic on the Southwestern Motorway is heavy at the SH20 link to SH1 southbound and heavy between Puhinui Rd and Mangere Bridge heading north.
Northbound traffic is heavy between Cavendish Dr and Mangere Bridge, and heavy at SH20 with SH20a.
Both directions of the Upper Harbour Highway are free-flowing.
