Wellington's diesel double-deckers will form part of a new fleet, which will be a mix of double and single-decker buses running on electric and diesel engines

The first of Wellington's new double-decker buses are in town, and almost ready to hit the streets.

The first tranche of Chinese-built diesel double-deckers arrived in Auckland last week and had made their way to the capital by the weekend.

One of those sitting at CentrePort was a fully-electric double-decker, while the other 28 buses were diesels that have been built to the current cleanest emissions standard.

KEVIN STENT/STUFF Wellington's new double-decker buses park up at CentrePort, awaiting their first commuter assignments on July 15.

The new lime-green and yellow buses are 12.8 metres long and carry just over 100 passengers. They will leave the wharf on Monday to make way for 40 new single-deckers that will be arriving on Thursday.

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The buses will begin operating in Wellington on July 15, when a comprehensive revamp of the city's bus routes and timetables will also take effect.

KEVIN STENT/STUFF The 28 Chinese-built double-decker buses are part of Tranzit's new 235-strong fleet that also includes new electric double-deckers.

Similar changes to the Hutt Valley's bus service kicked in on Sunday, which saw 30 new single-decker buses enter service, with another 65 to be rolled out on Monday.

Metlink asked commuters to bear with them while everyone got used to the new timetables, pointing out that connections between bus and rail services would not be perfect until new rail timetables were introduced on July 15.

The new buses will be operated by Tranzit, which has taken over 60 per cent of the Wellington region's commuter bus routes from NZ Bus, which operate the Go Wellington and Valley Flyer services.

TRANZIT An illustration of what charging poles would look like paired with the new upcoming electric double-decker buses.

Tranzit fleet and operations director Keven Snelgrove said nine more of the fully electric double-deckers would arrive at the end of the month and feature among the Wairarapa bus company's new $100 million-plus, 235-strong fleet.

The fully-electric double-decker bus fleet, which will be this country's first, has been trialled on Wellington's steep and windy streets, and had handled the terrain well, Snelgrove said.

"They use them in Hong Kong, which is just as rugged as Wellington with its hill work and tight winding roads."

The 82-seat double-deckers will be fully charged overnight, topping up their batteries during the day at various charging stations across the Wellington network.

Costing about $1.5m, the first charging station was installed in the suburb of Island Bay this month. It is thought to be the only one in the country and likely the Southern Hemisphere.

The electric double-deckers are two metres shorter than Wellington's trolley buses and 1.3 metres shorter than its existing diesel buses.

They will be used exclusively in Wellington city. Five will be operational from July 15 with the remainder being rolled out every week thereafter.

They will will run between the suburbs of Island Bay and Churton Park, and be joined by another 12 in 2021 with a further 10 added to routes in Brooklyn in 2020.