Wellington's commuter train company is calling yesterday's transport failure the worst scenario it could have faced.

There were just 19 buses available to replace Wellington's idle trains at the peak of Tuesday's power outage disruptions, train operator Transdev has revealed.

"That's not a lot of buses to move 5000 people in," chief operating officer Mike Fenton said.

A 4½-hour shutdown of the network was caused after an overhead power fault saw almost all services cancelled just before rush hour on Tuesday afternoon.

ROSS GIBLIN/STUFF Wellington commuters stuck at the railway station were offered limited bus replacements.

During the afternoon peak, about 17,500 people typically travel across Metlink's network.

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The outage was initially caused about 4.30pm by three faults to the electric wires in Wellington Railway Station, Fenton said.

ROSS GIBLIN/STUFF Commuter Melissa Devine, from Lower Hutt, said she was "severely frustrated" by the Tuesday rail disruptions which delayed her son's fifth birthday celebration.

"So there were three problems that they had to fix."

Power was then turned off to all platforms, in order for crews to repair them, he said.

"What we have to do is take care of the guys who are actually fixing the wires. So the issue actually last night was access for those guys to get under the wires.

MONIQUE FORD/STUFF Metlink advised stranded train passengers to seek alternative transport on Tuesday afternoon after the entire train network was affected by the power fault. All trains are scheduled to run on time on Wednesday.

"We have no knowledge of what caused it at this point."

He could not say whether the three power faults were on separate lines, but as far as he knew it was not caused by anything falling on the wires.

He could not rule out the heat playing a part. "It's certainly possible. I mean metal is impacted by heat, and all of those wires are made of copper."

Cancelled trains caused traffic to back up coming in and out of Wellington City on Tuesday afternoon.

A pantograph – the piece of equipment that sits on top of a train, connecting it to the overhead wires – was also damaged on one Metlink train last night.

The first services resumed soon after 7pm, but there were widespread delays throughout the evening.

Commuters complained of a lack of clear communication by Metlink about the outages, and long waits for limited buses.

"[The] station was heavily crowded and there was huge traffic," Kasun Dilunika, a regular commuter from Tawa, said.

"Bus replacements were there, but there was some queue. I didn't stay in the queue since I had very bad experience the previous time."

Fenton said Transdev would continue to review how it communicated with passengers, and provide backup options when and if such incidents happened.

Yes, how funny it us. After 44 minutes from this tweet I am stuck in a train near Wellington and tweeting 😬@metlinkwgtn — Kasun Dilunika (@dilunika) January 30, 2018

SH2 HOROKIWI - DELAYS - 6:35AM



Mōrena, #WgtnTraffic!

Due to a prior #crash (now clear) heading southbound just after Horokiwi, traffic on #SH2 is HEAVY a little earlier than usual. Please expect #delays. ^EL pic.twitter.com/Ac731aT1hC — NZTA Wellington (@NZTAWgtn) January 30, 2018

"We will debrief with our team this week and obviously accept a bunch of feedback from both customers and our client Greater Wellington Regional Council. We'll make adjustments to planning and preparation in dealing with events like this. "

"In reality, the only solutions we have where we have a network or infrastructure failure like this is to try and supply buses for alternative transport. And we are dependent on what buses we can source.

"Communicating a very clear plan when we in fact already don't know all the information is pretty hard."

Commuters who bought a train ticket yesterday and were affected by the outage will not get a refund.

Tickets and fares for trains are determined by the the Greater Wellington Regional Council, for which a spokesman said: "Our conditions of carriage say that we don't give refunds if a train can't complete its journey."

Tuesday's 10-trip tickets were not clipped, nor were people charged when using replacement buses, the spokesman said.

There were fresh delays for commuters on Wednesday morning, with trains cancelled between Trentham and Upper Hutt until 12.35pm so emergency repairs could be done to the track mechanism that directs the trains.

There were delays to arriving and departing services at Wellington Railway Station, and some trains were running with fewer carriages.​

