Motorists travelling through the Karangahake Gorge are being urged to plan ahead, with a series of daytime closures scheduled on State Highway 2 later this month and again in October.

New Zealand Transport Agency Waka Kotahi (NZTA) said in a statement that the closures were needed to allow rock scaling work on cliffs above the highway, helping improve the safety and resilience of the key regional route.

A 500m section of SH2 near the historic rail tunnel bridge, extending towards Paeroa, will be fully closed from 9am to 4pm daily during two work periods:

Monday, August 24 to Friday, August 28;

Monday, October 12 to Friday, October 16.

The daily closure times have been pushed back by 30 minutes from previous plans, allowing more commuter and school traffic to travel through the gorge before work begins.

NZTA said a full closure was required because loose rock and debris may fall onto the road while specialist crews work on the steep cliffs above.

While residents and property owners will still be able to access their properties from either end of the closure, through access will not be available except for emergency services.

Road users were encouraged to travel through the gorge outside the closure hours, while inter-regional traffic is advised to use SH29 over the Kaimai Range as an alternative route.

Rock scaling involves qualified crews using ropes to inspect cliff faces and remove loose or unstable rock with hand tools and specialist equipment.

The August programme would focus mainly on inspections and identifying areas that required treatment, with some rock removal expected.

More extensive rock removal and any additional work will be carried out during October.

NZTA said it would also use the planned closures to complete other maintenance and resilience work where possible, reducing the need for additional disruptions in the future.

The agency says weather or other factors could affect the work schedule and recommends drivers check the NZTA Journey Planner before travelling.