Watered to prevent issues

As temperatures across Wairarapa soared over the past few weeks, NZTA Waka Kotahi contractors were tasked with watering State Highway 2 to protect its surface.

Water trucks – capable of carrying up to 10,000 litres of water – have been spotted in both the north and southbound lanes of SH2, dousing the road with cool water while Carterton, Masterton, and South Wairarapa are under water restrictions.

NZTA’s regional delivery manager, Jetesh Bhula, confirmed that water was sourced from the Higgins compound; however, Times-Age reached out to Higgins at Waingawa, who advised that the Napier branch [who refused to comment] had received the contract for this work – nobody could confirm where the water was sourced.

“During the recent hot weather, contractors have been using water trucks to spray water to cool the road surface in the project area to manage surface flushing and seal bleed issues.

“This is important not only to protect the road surface but also to ensure vehicles aren’t affected by bitumen splash,” Bhula said.

On December 21, Times-Age reported an incident where the road surface had disintegrated, causing chunks of bitumen to separate from the road surface.

NZTA defines surface flushing as a “surface defect with bituminous binder near the top of or above the surfacing aggregate, which results in minimal surface texture,” which in warmer temperatures can result in the flush surface becoming sticky and soft – leading to “pick-up” of the surface.

Seal bleeding happens when surface and air temperatures are higher; the binder in chip seals becomes soft and starts to flow.

The binder can adhere to vehicle tyres in this softened state, which may “redeposit it on adjacent road surfaces”.

Bhula confirmed that it wasn’t “unusual” for warmer weather to create issues with new chip seals but that this “settles down over time”.

“Even some older seals can ‘liven’ up with the first flush of hot weather,” he said.

Water spray on the SH2 road surface to prevent the aforementioned issues from arising is being completed cyclically as needed.

“This has been more frequent during the recent spell of hot weather,” Bhula said, “The amount of water used varies according to conditions at the time.”

“Contractors source the water from the Higgins Depot/Compound. The project covers its cost,” he said.

Work on the State Highway 2 Safety Improvement project has commenced for the new year, and the project team are currently “carrying out line marking [including the installation of audio-tactile road markings].”

The raised table pedestrian on the Masterton side of the Ngaumutawa roundabout will also have work completed while crews complete other minor tasks before the completion of the project.

“The substantive road surfacing works needed for the project were completed in December.

“Additional work will be carried out late in summer,” Bhula said.