Wellington residents are being urged to avoid travel or find another way to work after a freight train derailed on Tuesday night.
The incident happened at around 7:40pm and has damaged the tracks and points where the Hutt Valley and Kapiti lines merge.
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Around 20,000 peak hour commuters have been thrown into chaos by the derailment which has affected almost all the lines
Operator Metlink says services have been stopped on Hutt Valley, Kapiti, Melling and Wairarapa lines. Trains will travel on the lines, but will stop outside the city.
Kapiti trains will run half-hourly between Waikanae and Porirua, Hutt Valley will be running to a half hour timetable between Upper Hutt and Petone.
All Melling line services are cancelled and the Johnsonville line is unaffected.
Metlink has been able to source some bus replacement services, but they are extremely limited. Six buses departed from Masterton headed into Wellington at 6:47am.
Train tickets will be accepted on Metlink buses.
Commuters from the Hutt Valley and Kapiti should seriously consider staying home, Greater Wellington regional councillor Daran Ponter told Newstalk ZB.
He said there simply aren't enough buses to handle a total network shutdown and commuters will have to fight for a spot.
"I'm afraid for those people who are relying on buses it is going to be a little bit like the Hunger Games out there."
Video posted to Twitter by the New Zealand Transport Agency shows motorways packed with traffic as commuters try to make their way in by car.
"#WellingtonTraffic should expect additional delays this morning, as there will be no train services on the Hutt, Kapiti, Melling & Wairarapa lines due to a derailed freight train," the tweet said.
Metlink says it does not know how long it will take to get the service back on track, but disruptions are expected to continue into the afternoon.
Crews worked throughout the night in an attempt to fix the damage.