"We have sourced a limited number of shuttles for passengers wishing to travel between Porirua and Waikanae however due to an earlier slip on State Highway 59, traffic is heavily congested. We recommend seeking alternative transport where possible and offer our apologies for any inconvenience."
Commuter Gary Henson told Stuff the train was full of passengers when it came "to an urgent halt ... in the middle of nowhere".
No injuries have been reported.
Earlier on Thursday, multiple slips blocked traffic in both directions on the main highway between Wellington and Kāpiti.
Motorists were asked to expect significant delays after a slip came down at Pukerua Bay on State Highway 59 - formally State Highway 1 - at around 1.25pm.
Heavy congestion remained throughout the afternoon, with stop-go traffic management put in place at around 4.30pm.
Waka Kotahi issued an update just before 6pm to say the road was open in both directions.
