Sections of Auckland's motorway network are moving at snail's pace after two crashes this afternoon.

In the latest crash, a left-bound lane heading northbound over Auckland's Harbour Bridge is blocked after Curran St and queues stretch back to Spaghetti Junction.

Waka Kotahi NZTA says emergency services and contractors are on-site and motorists heading to the North Shore should expect delays.

Traffic remains gridlocked in the opposite direction on Auckland's Southern Motorway after a smash involving a truck and two cars blocked two lanes near Greenlane.

All lanes have now been cleared but motorists are still facing long queues stretching back 8km.

Waka Kotahi NZTA is warning motorists using the motorway to be prepared for long waits after the accident left two southbound lanes impassable just after 2pm.

It said the smash happened between the off-ramp and on-ramp at Greenlane.

The accident, which involved a truck and two cars, blocked the left-hand southbound lane after the vehicles were shifted to the side of the road for 30 minutes.

Police say no one was hurt.

"Please expect delays and pass with extra care," NZTA warned.

It said queues on the four-lane of stretch of motorway were back to Newmarket.

Soon after, Google traffic maps showed gridlocked queues stretching back St Mary's Bay and adjoining Northwestern Motorway link.

Yesterday the New Zealand Transport Agency warned strong winds were expected to affect the Harbour Bridge today between 6am and 4pm.

It said speed restrictions and lane closures were likely and a full closure possible if winds gusted over 90km/h.

Caution was advised, especially for high-sided vehicles and motorcycles. The agency urged drivers to take care and expect delays.