A 4km section of Auckland's Northern Motorway will be closed five nights a week for the next four months, starting tonight.

The NZ Transport Agency (NZTA) says the motorway will be closed between Upper Harbour Highway/Constellation Dr and Oteha Valley Rd from Sundays to Thursdays between 9pm and 5am.

NZTA advises motorists to allow more time if travelling at night on the Northern Motorway in coming months.

The closures will allow crews to start preparations for the Northern Corridor Improvements (NCI) project, a new link between State Highway 1 and State Highway 18 due to start later this year.

They will be resurfacing the motorway, painting new line markings and moving median barriers and overhead gantry boards, says the agency's senior manager project delivery, Chris Hunt.

The repainted lanes will be narrower, so as the work progresses along the 4km stretch of motorway, the speed limit will be reduced to 80km/h.

"The work is being carried out at night to reduce disruption and delays on the roads and motorway during the busiest parts of the day. Closing the motorway ensures the safety of our crews working at night and all other road users," says Hunt.

The closures will apply to all lanes and the on- and off-ramps between the two interchanges, including all ramps at the Greville Rd interchange.

Vehicles will still be able to travel northbound from the on-ramps at Oteha Valley Rd, and travel southbound using the Upper Harbour Highway/Constellation on-ramp to the city, as well as drive along Greville Rd.

There will be separate signposted detours for north- and southbound traffic.

"Vehicles will be directed along the same detour routes every night, making it easier and more familiar for people who travel regularly at night. But drivers will need to plan ahead and allow more time for their journeys," says Hunt.

"We thank you in advance for your support, and apologise for any inconvenience this work may cause."

The NCI project will build a new motorway connection between SH1 (the Northern Motorway) and SH18 (Upper Harbour Highway) to complete the Western Ring Route, upgrade Upper Harbour Highway, add new lanes to SH1, extend the Northern Busway and add more than 7km of new walking and cycling paths.

It is scheduled to be completed in stages over the next three years.