New technology forcing motorists to drive to the conditions on the notorious road over the Kaimai Range will be unveiled today.
New Zealand's first weather-activated road signs, on State Highway 29, are ready to go.
There are 22 signs on a 12km stretch between Waikato and Bay of Plenty, part of a two-year NZ Transport Agency trial aiming to reduce crashes on the steep and sometimes slippery road.
The signs, and four web cameras, will be linked to a weather station at the summit of the range and the transport agency will monitor conditions and adjust speeds to between 30 km/h and 100 km/h.
These speeds will be enforced by police.
Transport agency chief safety adviser Colin Brodie said the trial aimed to encourage drivers to travel safely when rain, ice and fog hit.
"Our data shows that over 70 per cent of the crashes on the Kaimai Range happen in wet weather, and that over 40 per cent of these were caused by drivers travelling too fast for the conditions," he said.
"Despite the changeable weather on the Kaimai Range people still attempt to travel at 100km/h.
"These signs will allow us to drop the speeds to 60km/h on the Waikato side and 80km/h on the Bay of Plenty in adverse weather.
"They will also be used during road works or in the event of a crash, when speeds may be reduced to as low as 30km/h."
If successful, similar technology could be installed on other roads, Mr Brodie said
The new signs will turn on at 9am today.