The rollout of Wellington's promised new electric hybrid bus fleet remains up in the air.

The first prototype for Wellington's possible new electric bus fleet has passed an important test, but there is still no guarantee the vehicles will be rolled out in the capital.



NZ Bus announced in April 2016 it had signed a $43 million deal to fit a large number of its 1100 buses in Wellington and Auckland – including the capital's now-retired 60 electric trolley buses – with Wrightspeed motors, which operate mostly on rechargeable electric batteries.



​The project has run into various problems, and NZ Bus admitted late last year it was exploring alternatives to the Wrightspeed technology after the first gearbox was deemed not suitable for the prototype.

The trolley buses were retired in October, with surplus diesel buses from Auckland replacing them in the meantime.

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MAARTEN HOLL/STUFF Greater Wellington regional councillor Daran Ponter says there is "no chance" the Wrightspeeds will be rolled out when new bus contracts and routes take effect in July.

NZ Bus chief executive Zane Fulljames confirmed on Wednesday the prototype had recently received a certificate of fitness, which meant it was roadworthy, but he was far from optimistic about what that meant for the project's future.

When asked if the recent development made him more confident the technology would succeed, Fulljames was non-committal.

"It's an important milestone," he said.

MAARTEN HOLL/STUFF The capital's electric trolley buses were retired in October, with diesels sent from Auckland to replace them.

The vehicle had been road-registered by California-based Wrightspeed, but final testing still needed to be carried out.

"When they've completed that final testing, all going well, they'll hand that [motor] over to NZ Bus and we'll commence our final acceptance testing."

Fulljames was unable to give a timeframe on when that might happen.

MONIQUE FORD/STUFF NZ Bus chief executive Zane Fulljames (centre) said alternatives to the Wrightspeed technology were still being explored.

He confirmed the company was still exploring alternatives to the Wrightspeeds.

"We're exploring other providers of electric vehicles and electric power trains."

But other options included reverting to diesels instead, or consigning the vehicles to the scrapheap.

Greater Wellington Regional Council is hoping the Wrightspeeds will be in place when new bus routes and contracts come into effect from July.

Fulljames said he could not guarantee that would happen, but the company would provide the number of buses it had agreed to in one form or another.

It was initially hoped the Wrightspeeds would be introduced last November, after the trolleys were retired, but that was pushed back to July.

The regional council's sustainable transport committee deputy chairman, Daran Ponter, said he did not expect the Wrightspeeds to be operating by then.

"I don't think there's a chance the technology is going to be rolled out by the 1st of July.

"But if the vehicle proves itself for NZ Bus, then there's a possibility that we might see increasing numbers of these buses towards the end of the year, or in 2019."

While the first prototype was now road worthy, a significant amount of testing had to be done to see if the bus was up to the task, and a supply chain then had to be put in place to get the remaining 59 buses up and running, Ponter said.

No other city in the world had yet adopted the new technology.

Committee chairwoman Barbara Donaldson reiterated that the NZ Bus contracts had never been dependent on providing electric buses, but that was the council's preferred option.

"We have this vision of becoming an all-electric city so we want to make progress on that as fast as we can."