Those heading back to work in the main centres could face a sea of orange cones and a disrupted commute as summer roadworks are in full swing.

Photo: RNZ / Emma Hatton

Wellington and Auckland are both undergoing significant infrastructure improvements, which may delay drivers heading into the city.

While some might still be lazing on a beach - others might find themselves trying to avoid fluro jackets and cones.

In Auckland the cones have become a staple of the city's layout, but the works aren't expected to slow commuters as they filter back to work.

Auckland Transport's Mark Hannan said because schools and university aren't back until the end of January, there should not be any problems.

"There are a lot of roadworks in Auckland at the moment, this is the traditional time to do the works.

"The traffic levels are probably about half what they normally are, and the weather is good. So it's a good opportunity to get in there and get some of this overdue work done."

Hannan said the only road in the city that people would notice was significantly different was Victoria Street which was down to one lane in each direction.

He said all other motorway networks and major roads will be operating as normal.

Two main routes closed in capital

But in Wellington both Wallace and Willis Streets - main routes for the city - are closed.

The installation of new water mains along Wallace Street started on 5 January - something that needed to be done before the city could begin work on the massive new Omāroro water reservoir.

Wellington Water's major projects manager Stephen Wright said the work could take up to 10 weeks, but further works would continue into mid-2020.

"There'll be another piece of work after that to lay some of the smaller pipes along Wallace Street that will take either about 10 to 20 weeks depending on the methodology we adopt - either closing the road or using a stop/go traffic management."

And while the arterial route is closed, the 20,000 vehicles a day that use it, will be diverted along Wright Street.

Traffic modelling had showed the smaller, quieter street was up to the task of handling the traffic, but there might be a couple of teething days as commuters get used to the change, he said.

Parts of the central city's Willis Street were also expected to be closed for the next two months while they replaced piping following a sewage tunnel collapse.

With most public transport back up and running for the year, Wellington's Chamber of Commerce said those who had run out of holidays would be back to work.

Its chief executive John Milford said despite the inconvenience for those heading into the office, the repairs needed to be done.

"Given the amount of work that needs to be done on infrastructure, I think it's something that needs careful planning but also I think people can't have both - they either get the upgrades they require and need to the transport infrastructure.

"That is going to be some inconvenience but I mean it's pain for gain," Milford said.

He said some companies might extend their holiday period to use up the newly allocated four weeks of annual leave for staff.

But if you are rolling up your towel and putting away the stubbies, the advice is to give yourself extra time to get to where you are going and pay attention to the changes.