Motorists are being warned of significant delays on Auckland's northern motorway this weekend while road works are carried out.

The New Zealand Transport Agency says two weekend closures this month - the first this weekend - will have a big impact on people using the Greville Road interchange on the motorway (SH1).

One of two lanes at the Greville Road off-ramp would be closed from tonight until Monday morning and there would be other restrictions as preliminary work is done to prepare the interchange for traffic signals.

"That area is very busy on the weekends, and we expect some significant delays," said NZTA state highway manager Brett Gliddon.


"We're asking people to help us complete our necessary work as quickly as possible by using alternative routes, or allowing plenty of time to get through the interchange."

There would be sign-posted detour routes but Mr Gliddon said local roads were also expected to be busy and people using the detours should allow plenty of time to get to their destinations.

"To get the roundabout ready for traffic signals, we need to relocate some existing underground services like power and water and reconstruction of the road itself.

"These closures are an essential step to complete the Upper Harbour Highway to Greville upgrade, and we do appreciate the patience and support we are getting from drivers and businesses in the area while we get on and do this work as safely as possible", Mr Gliddon said.

The second weekend closure is planned for October 17 until October 20.

Both weekend closures are dependent on the weather.