Motorists south of Whangārei face up to hour delay on SH1 while slip repaired on Brynderwyns

Delays of up to an hour are expected for those crossing SH1 at the Brynderwyns, south of Whangārei, next week while this big slip is repaired. Photo / Supplied

Motorists driving on State Highway 1 over the Brynderwyns next week will have their journey disrupted - with delays up to an hour expected - while repairs are done on a slip.

Waka Kotahi NZ Transport Agency will be fixing a slip on the south side of the Brynderwyn Hill, south of Whangārei, caused by recent weather events.

The work will take place between 6am and 5pm so that workers have full visibility to ensure their safety, Waka Kotahi said.

No work will take place during the night or on the weekend, with the repairs planned to start on Tuesday, and is expected to be complete by Friday, September 30.

The national roading body said it is critical that the slip repairs are completed as soon as possible to avoid further movement which would impact the lane and require more invasive and lengthy repair work.

During the work, traffic management and a temporary speed limit of 30km/h will be in place between Atlas Quarries at the south side of the Brynderwyn Hill and the summit.

While SH1 will remain open, significant delays of up to 60 minutes are expected.

''We encourage road users to use the suggested alternate route via Kaiwaka Mangawhai Rd to the south of the site and The Braigh in Waipū in the north. This route is expected to add 20-40 minutes to the journey. Please plan your journey at journeys@nzta.govt.nz/traffic and allow time for the delays,'' it said.

The slip on the south side of the Brynderwyns that will see traffic disrupted next week while it is repaired. Photo / Supplied

For maximum efficiency, general maintenance will be also undertaken while traffic management is in place at this location and all work is conditional on weather events and other disruptions.

''Buses and over-dimensional/heavy loads will be given priority through the stop/go closure, however we do encourage the use of the alternate route if at all possible.''

An underslip occurred previously in July which is why the temporary speed limit has been in place at the slip site. Then earlier this month a second slip occurred.

''Geotechnical advice was that the new slip poses a risk to the road such that we may have to reduce the road to one lane within the next few weeks. That's why the decision to undertake the emergency work as quickly as possible to protect the road has been made and hence the relatively short notice period.''