NZ Transport Agency will close a section of State Highway 36 to wash rocks off the sides of the Mangorewa Gorge on Wednesday – a day forecast for strong northerlies and heavy rain.

The highway through the gorge at the top of the Pyes Pa Road will be closed from 9am to 4pm Wednesday, unless the weather is too poor for the helicopter to work in.

A slip on SH36 closed a section of the highway during storms in April.

The plan is to drop about five tonnes of water above a section of the road, to flush soft soil and vegetation off the rock.

The section of SH36 has been reduced to a single lane since Easter weekend, when there was a large slip in heavy rain. If the weather matches the forecast, the work will take place on next clear day.

The road closure time is chosen to allow commuter traffic travelling between Rotorua and Tauranga to pass during peak hours.

The NZ Transport Agency advises motorists wishing to travel during the closure to use State Highway 2 (SH2) /State Highway 33 (SH33) via Te Puke.

The work is preventative and will make the section of highway safer for motorists by preventing slips in the future, says the transport agency's Bay of Plenty highways manager Brett Gliddon.

Contractors will use diggers and trucks to move the soil offsite, leaving hard rock above the single lane section, says Brett.

'The Transport Agency apologises for any inconvenience but we are focused on creating safer journeys for road users,” says Brett.

'We appreciate motorist's patience while these important works are completed.”

The road will be reopened to one lane after the helicopter is finished to allow contractors to clear the soil and vegetation off the highway.

Weather permitting it is expected both lanes will be fully open by Saturday June 28.

For real time information on highway conditions and incidents visit www.nzta.govt.nz call 0800 4 HIGHWAYS or follow @nztawaibop on twitter.