A truck crash on State Highway One north of Auckland has blocked a diversion route put in place after a separate crash.
One person is in a serious condition after two vehicles crashed on State Highway One at Wayby Valley in Rodney.
Then a truck using an alternate northbound route hit a rail overbridge at Kaipara Flats Road.
That has blocked both lanes on the diversion road.
Police say delays will be considerable and adivse people to postpone their travels.