Newmarket Viaduct, Cantilever bridge in Newmarket, New Zealand.

Newmarket Viaduct is a seven-lane state highway viaduct, 700 m long and up to 20 m high, carrying the Southern Motorway over the Newmarket suburb of Auckland. The current structure is built from 468 pre-cast concrete sections made off-site in East Tāmaki and lifted into place by a launching gantry. It has solid concrete crash barriers, noise-absorbing asphalt and partial noise walls.

The original structure was completed between 1962 and 1966 and represented an engineering milestone for cantilever bridges in New Zealand. It was later completely rebuilt to meet modern standards and capacity needs.

The viaduct takes its name from the Newmarket suburb it crosses. Its replacement brought urban design work beyond the road itself, including a volcanic-themed walkway running from Gillies Avenue down towards Newmarket and connecting to Clovernook Road. The structure is a prohibited route for overweight vehicles, so such trucks are forced onto city streets instead.

The viaduct is a motorway structure with no pedestrian or cyclist paths, so it cannot be walked or cycled. A volcanic-themed walkway runs from Gillies Avenue down towards Newmarket, connecting to Clovernook Road, and offers a ground-level route past the structure. Traffic on the seven lanes exceeds 200,000 vehicles a day, the heaviest count on any road section in New Zealand.

The replacement was built in stages so traffic kept flowing: a new four-lane southbound viaduct went up north-east of the old one, the old southbound lanes were demolished, and the northbound lanes followed in the gap. A 140 m, 800-tonne launching gantry lifted 468 precast concrete sections made off-site in East Tāmaki.