A truck and two vehicles crashed on Manakau North Rail Overbridge on State Highway 1 south of Levin shortly before 6.21am on Friday.
Three people were injured. One person suffered critical injuries and was airlifted from the scene before being transported by road ambulance to Wellington Hospital. Two others in moderate condition were assessed at the scene and did not require hospitalisation.
The truck became wedged between guard-rails on either side of the bridge. State Highway 1 was reopened at about 1pm. Horowhenua Mayor Bernie Wanden said "those bridges are notorious, dangerous and have been for many decades".