A nose-to-tail crash on State Highway 1 in Wellington caused southbound traffic to stretch back to Porirua on Wednesday morning.
The crash occurred in the Churton Park area.
Two trains were cancelled on the Hutt Valley line due to mechanical problems.
There were 40 minute delays on the same route because of a points and signals fault at Trentham.
Buses were brought in to help clear a backlog of passengers.