The critically injured driver - a 21-year-old man - was flown to Waikato Hospital by Taupo's Greenlea Rescue Helicopter, while the road remained shut until 1pm yesterday.
Conditions were expected to improve today but were treacherous yesterday and it was snowing when emergency services arrived, Troy said.
"It was cold and there were patches of ice on the road and when emergency services arrived it was snowing as well."
He said the occupants of the car were not skiers.
The 16-tonne, four-axle truck was carrying waste substances but none of it leaked out.
Troy urged motorists to take care while travelling along the Desert Road this winter.
"The Desert Road is notorious for changing conditions. You can have beautiful weather on one side of the hill and on the other side you can have black ice and ice and snow so we encourage all motorists to take extreme caution when travelling through the Desert Road area."
An NZME reporter who flew over the scene yesterday described it as "horrific", saying there was lots of smashed glass among the snow and ice.
Snow has been falling in the area. MetService had issued a warning for the road yesterday, while the Turoa and Whakapapa skifields received a good dusting.
Meanwhile, the latest Ministry of Transport data on road deaths proves a dire read: 181 people - excluding those killed in yesterday's crash - have died on the roads compared with 176 at the same time last year.
The statistics show 127 of those killed were men and 54 women. June and February were the deadliest, with 31 people dying in each month.
