Police and Downer EDI Works contractors in Queenstown were kept busy yesterday morning as treacherous black ice quickly formed on State Highway 6 between Arrowtown and Frankton.
Peak morning traffic crawled bumper to bumper between the Threepwood development, near Lake Hayes, and the Lower Shotover Bridge as police and New Zealand Transport Agency contractors slotted their vehicles in the traffic and actively made motorists drop their travelling speeds.
NZTA Central Otago area manager John Jarvis said a light fall of snow, which began about 7am, froze almost instantly on the highway, creating sheets of black ice.
By 8am, heavy morning traffic travelling east to Queenstown made it "almost impossible" to spread grit over the icy patches, Mr Jarvis said.
"They tried to control the speed of the traffic by slowing it down through their own vehicles slotting in among them."
Mr Jarvis said the issue was resolved just after 9am.
Weather forecaster David Crow said the overnight low on Wednesday in Queenstown was -3degC, with a ground temperature of -7.8degC.
Arrowtown experienced "almost tropical" temperatures compared with Wednesday morning's -12.1degC ground temperature and -8.8degC air temperature, recording -10.9 on the ground and -6.7 in the air.
Mr Crow said more heavy frosts in the Wakatipu were predicted over the weekend.
