Electronic warning signs at one of Wairarapa's most dangerous intersections are about to go live.

The new warning signs installed at the intersection of East Taratahi and Wilton Roads with State Highway 2 are expected to be operational by the middle of the month.

New Zealand Transport Agency regional performance manager Mark Owen said the signs should reduce the severity of crashes at high-risk rural intersections by reducing the speed on the main road.

"This intersection has a history of crashes and, while there have been no recent fatalities, installing this new system should help improve safety for all road users," Mr Owen said.


"The greatest proportion of intersection crashes within high-speed environments are crossing or turning crashes between two vehicles. We know that the risk of serious injury or death from side-impact crashes increases significantly above 50km/h, so getting motorists to slow down when there is another vehicle approaching this intersection should help prevent crashes."

The signs have been successfully used in other parts of the country, including Kaiapoi and at Himatangi, he said.

The signs will activate if a vehicle is waiting at, or approaching, the intersection from the side road.

The warning sign will then flash and illuminate, reducing the speed for vehicles on State Highway 2 from 100km/h to 70km/h, a legally enforceable speed limit. If there are no vehicles waiting or approaching on the side roads, then the open road speed limit of 100km/h will not change.

Masterton Acting Traffic Sergeant Shayne Nolan said police would be enforcing the new reduced speed limit, although there would be times when they would need to use judgment.

"We will know when that sign changes and we will be able to see and judge how far away they [drivers] are and if they would have a reasonable amount of time to react.

"Obviously, there will be some judgment calls on it, because we've got to give people a reasonable amount of time to react to the sign but people can't ignore it and not expect enforcement action to be taken."

A light on the back of the sign would be illuminated when the sign was activated, which would mean police would know when drivers should be slowing down.

The intersection was a high-crash area, with a crash there as recently as last weekend, Mr Nolan said.

"I can only see it having a positive effect on the number of crashes, as long as the public takes on board the reasons for it."

As well as reducing crashes, it was expected the signs would improve the flow of traffic, he said.

"It's not just so that people can slow down and have more time, it's so that if the traffic slows down it gives more time for turning traffic to fit in."

No changes were expected to be made to the passing lane.

Wairarapa Road Safety Council manager Bruce Pauling said the initiative was a good idea.

"It has always been an intersection of concern and we do know any turning accident can often result in serious injuries or death because of the nature of the impact and the speed of the vehicles."

Preliminary data showed the signs were successful in reducing speed, he said.