Motorists heading south are being urged to expect delays and avoid travel.
Traffic on State Highway 1 north of Wellington ground to a standstill for hours on Friday after a serious crash, reportedly between a car and a van.
Delays remain after both right-hand, airport-bound lanes temporarily blocked traffic.
Drivers were trapped for hours on the motorway between Tawa and Churton Park last night.
Some stranded drivers abandoned cars and walked across SH1.
Emergency services are responding to a two-vehicle crash near Vinegar Hill Rd.