Commuters are in for headache crossing Auckland Harbour's Bridge this evening as a breakdown blocks one lane heading to the North Shore.

NZTA is advising motorists to pass the scene with care and to expect delays.

A crash on the South Western motorway is also causing issues, and one southbound lane is blocked just prior to the Walmsley Rd off-ramp.

Shortly after the crash, traffic was backed up to Mangere Bridge.