Auckland's southern motorway is heavily congested, with long queues building at the Greenlane off ramp as camping enthusiasts flock to a caravan and motorhome event at the ASB Showgrounds.
NTZA said motorists should expect delays and avoid the area if possible.
The Motorhome, Caravan and Outdoor Supershow is on until 5pm and continues tomorrow between 9am and 5pm.
Earlier today NZTA warned road users of possible delays in the area.
Traffic is also heavy coming into the city from the south and out of the city further north, with congestion northbound between Drury and Takanini and northbound between Puhoi and Warkworth.
NZTA said drivers in these areas should also expect delays.