Warning over black ice after drivers crash

Drivers are being warned over black ice on Northland roads.

Black ice on a Northland bridge saw the drivers of two vehicles crash off the road only minutes apart.

Police are hoping the bridge will get some much-needed maintenance work to stop further crashes this winter. The first vehicle, a saloon car, was heading east towards Rawene on State Highway 12 when the female driver lost control when the car hit black ice on a bridge near Whirinaki about 7.45am yesterday.

Senior Constable Jeff Cramp, of Rawene police, said the bridge over the Whirinaki River was on an exit to a corner on the road and the driver over-corrected after striking the black ice. She went off a wide verge and into a tree, before bouncing back and landing near a fence. The vehicle ended up 100m from the bridge but the driver was not injured.

Mr Cramp said only minutes later a male driver of a twin cab ute did the same thing and his ute struck the front of the first vehicle. Fortunately the driver was not in the car. The 63-year-old man suffered cuts to the top of his head, face and knee and required stitches from St John staff who were called to the scene.

Mr Cramp said the surface of the bridge was polished tarseal and there were potholes that had filled with water the previous day. In the shade the water on the bridge surface had frozen in the morning frost.

Roading contractors hosed off the bridge but Mr Cramp said Transit needed to put down some heavy chip to improve the bridge's dangerous surface.

Black ice, sometimes called clear ice, refers to a thin coating of glazed ice on a surface. While not truly black, it is virtually transparent, allowing black roads or the surface below to be seen through it - hence the term "black ice". The typically low levels of noticeable ice pellets, snow, or sleet surrounding black ice means that areas of the ice are often practically invisible to drivers or people stepping on it.

There is, thus, a risk of skidding and subsequent accident due to the loss of traction. A similar problem is encountered with diesel fuel spills on roads.