Officers had opened one lane about 2pm after heavy traffic started to back up.
About 10 minutes after being alerted to the highwaycrash police were called to a crash on Rust Ave in central Whangārei after a rubbish truck struck the railway overbridge.
A second vehicle, a Toyota Landcruiser, was also involved and the driver was being checked over by St John ambulance staff but was thought to have only minor injuries.
Police asked motorists avoid the area as they organised the removal of the truck and second vehicle.