A freight train derailed last night damaging the railway tracks.
An estimated 20,000 commuters are affected this morning.
Most Wellington train services are cancelled.
The Johnsonville line trains are unaffected and still operating.
Rail operator Metlink says it hopes to have rail services restored by this afternoon after derailment damage forced 20,000 commuters to find another way to work - or stay home.
Train services in and out of Wellington on the Hutt, Kāpiti, Melling and Wairarapa lines have been cancelled until further notice after a derailment last night damaged the tracks.
Metlink has not been able to source enough replacement buses to transport the roughly 20,000 passengers who travel by train during the weekday peak morning period.
Greater Wellington regional councillor Daran Ponter told Newstalk ZB that those who live in Hutt Valley and the Kāpiti Coast should consider staying home.
"A freight train has taken out the signalling in the choke point in the Wellington railyard."
It's the place where all the trains are coming into the city, he said.
Repair work would not be completed until the afternoon at the very earliest, and possibly not completed today, he said.
"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."
There are just not enough buses to cater for a total shut down, Ponter said
"Bus seats will be tight."
Most train services in and out of Wellington have been cancelled today.
Please make alternative transport arrangements where possible to ensure you arrive in time for your court events.
Ring 0800 COURTS if this issue will impact on your ability to appear at court.
— Ministry of Justice (@justicenzgovt) July 2, 2019
Trains could be back for afternoon peak
Metlink's general manager Greg Pollock said they hoped train services would be running before the afternoon peak.
The train derailment caused eight points, which are like intersections on the tracks, to be damaged.
Crews were currently working on fixing three of the points which would allow access to Wellington Railway Station, Pollock said.
"It's our intent at this stage [to have it running by afternoon peak] but we just need to wait and see how quickly teams out there on site can get the work done.
"Safety's our most important priority so if we are not 100 per cent confident things are ready to go then we will need to delay unfortunately."
Pollock apologised for the disruption to customers and said staff were trying hard to work as quickly as they could to get it fixed.
"We are trying to get limited bus replacements in place but it's challenging trying to find them at short notice."
Pollock said it would be best for commuters to check for updates on the Metlink app, at station and platforms or through the media.
Greater Wellington Regional Council chairman Chris Laidlaw said today's chaos was "a failure of our KiwiRail system".
"It's a product of, I suspect, ageing infrastructure.
"We depend crucially on that government-owned infrastructure to make the system work."
Laidlaw said there had been "quite a lot of money" dedicated to upgrading the network in the rest of the region, but more needed to be done in the central city.
"This has happened before and it will happen probably again until the KiwiRail asset is upgraded."
Laidlaw also asked people to understand why there were not enough replacement buses.
"Look, there is no large pool of buses held in reserve sitting and waiting at the depots. The bus companies don't do that and you can understand why."
Thousands pouring into city every day
Wellington Chamber of Commerce chief executive John Milford said if it was just the 20,000 commuters affected, the situation would not be so bad.
However, there were at least 40,000 people coming into the city from the north every day, all affected by a lack of resilience in the infrastructure.
"We have a limited number of roads and a limited number of rail lines, and if something happens to them we get this chaos," he told Newstalk ZB's Kerre McIvor.
"It's all about resilience. We need more money invested in resilience.
"We keep going on about it in Wellington, and where we think we're going to make progress, these things have just been deferred for the future."
More corridors needed to built to provide other avenues for people to get in and out of the city, whether it be by private car, public transport, or another method, but at the moment something like a slip could wipe out SH2, blocking off thousands of people from the Hutt and Wairarapa.
Business paid for Ubers for staff
Paul Retimanu, who runs Karaka Cafe and the Wharewaka Function Centre on the waterfront said they'd had to pay for Ubers for two of their staff, costing about $63.50 each.
He said the effects of the traffic woes were twofold - staff unable to make it in, and customers also stranded.
Problems of this scale did not happen regularly, but Retimanu said something needed to be done.
"Things out of our control are starting to creep up that wouldn't have crept in five or six years ago."
One business in Carterton is offering free coffee to stranded commuters.
3mile Coworking Community, a shared business hub in the Wairarapa town, has experienced a steady stream of displaced passengers, all of whom have been provided with free coffee.
Rail users disappointed
There had been many disappointed people as they arrived at Paraparaumu Railway Station this morning.
"One guy was swearing his head off," Railhouse Coffee shop barista Dylan Whyte said.
"People have to get into Wellington for various reasons, some more important than others."
Shop owner Ann-Maree Trott said her son drove from Wellington to pick her husband up at Porirua Railway Station.
"He had to get into town because he's got an important meeting with people who are coming in from overseas."
The Kāpiti line is on reduced services with trains only operating between Waikanae and Porirua.
Traffic was busy as people have driven to the park and rides along the network, seen the cancellations, and hopped back into the car.
NZTA has warned motorists to expect "significant" delays on major highways near the capital, as southbound traffic was heavier than usual as of 6.40am.
WELLINGTON TRAFFIC - SIGNIFICANT DELAYS – FINAL UPDATE 9:45AM
Congestion has largely EASED on both SH1 and SH2 after this morning's delays. Traffic is still heavy from Johnsonville on SH1 and from Petone on SH2, though delays are easing quickly.
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6:40AM WED 3 JULY
Commuters in the Wellington region should expect additional delays throughout peak hours today, as there will be no train services running to and from the Wellington Station on the Hutt, Kapiti, Melling and Wairarapa lines due to a derailed freight train.
During this time, there will be as many as 20,000 extra passengers on the State Highway network during peak hours.
Please plan ahead before travel, allow extra time, or consider delaying your journey.
For more information, please visit: www.metlink.org.nz/service-updates/tomorrow-mornings-peak-services-may-be-affected-by-tonights-disabled-freight-train/ ^RS
While the main highway route in and out of the capital is expected to become heavily congested with extra traffic, a handful of tourists remain at the eerily quiet Wellington Railway Station.
Sally Rose, from Louisiana, was hoping to travel on the Northern Explorer to Auckland.
Rose said they were looking at booking a $500 flight to make the journey instead.
"It's a bummer that we don't get to see the route we wanted to see but it's okay."
After avoiding the mad rush by leaving Wairarapa at 5.30am, commuter Martin Grimshaw is unsure how he is going to get home.
Grimshaw managed to grab a ride to Wellington with his daughter after he stayed up past midnight to get the latest information on the train cancellations.
"There have been quite a few problems on this line, but I have never known complete cancellation," he said.
"If there is, it would tend to be [organised] in advance with bus replacements.
"They put six buses on but that would be nowhere near enough for the commuters from the Wairarapa."
Grimshaw said it was annoying that he had already paid for the cancelled train service in advance by signing up for a monthly pass.
"Anyone with a monthly pass is going to lose out on a day's travel."
KiwiRail chief operations officer Todd Moyle said that about 7.40pm last night a number of wagons on a freight train leaving Wellington freight yard derailed.
"The wagons remained upright but it took the locomotive engineer 230 metres before he was able to stop the train, leaving damaged tracks and points on the main tracks into Wellington."
KiwiRail brought in two cranes and staff from across the North Island to support local staff in removing the damaged wagons and repairing tracks overnight, he said.
The cause of the derailment is being investigated, he said.
Kāpiti line: Reduced train services stopping at all stations will run on a half hourly timetable from 6am between Waikanae and Porirua only. If you are wanting to travel between Porirua and Wellington Metlink recommends alternative transport or avoiding travel.
Hutt Valley line: Reduced train services stopping at all stations will run on a half hourly timetable from 6am between Upper Hutt and Petone only. If you are wanting to travel between Petone and Wellington Metlink recommends alternative transport or avoiding travel.
Wairarapa line: Six buses will travel between Masterton and Wellington in the morning, which will be departing at 6.47am only. Metlink recommends alternative transport or avoiding travel.
Melling line: All Melling line services are cancelled. Metlink has asked commuters to arrange alternative transport or avoid travel.
Johnsonville line: Train services will continue to run to timetable on the Johnsonville line as it is not affected by the derailment.
KPL/HVL/MEL/WRL: Avoid travel if possible or arrange alternative transport as we have no services in and out of W... https://t.co/gB8EVSY6JF