Train passengers travelling between Wellington and the Hutt Valley are being warned to expect more delays after two serious crashes closed the rail route beside State Highway Two.
About 3000 litres of diesel was spilled when a truck and fuel tanker collided at 5.15am.
At about the same time, a car hit a power pole, blocking the other side of the highway and leaving an occupant with serious injuries.
The Transport Agency says traffic is now flowing freely, but Trans Metro says rail passengers should expect further delays during the afternoon as the backlog is cleared.
Wellington Regional Council says there is no risk of diesel reaching the harbour or other water sources and a tanker capable of sucking up the remaining diesel will help to clean up the spill.