A combination of freezing temperatures, fog, hoar frosts and black ice means challenging conditions for travel on State Highways 8 and 80 over the next few days, the biggest concern being drivers not adapting to the conditions.
In a statement, NZTA system manager Mark Pinner said "On SH8 in particular, there are many sheltered areas where build-up of ice is a major concern."
Mr Pinner said bridge surfaces could cool quickly, and re-freezing could even occur in the late morning.
"We’ve already had reports of people driving too fast for the conditions and truck and trailer units fishtailing. We also know it’s going to get busier later in the week, as we get closer to the long holiday weekend for Matariki. Reducing speed is the biggest thing drivers can do to keep themselves safe and to help keep the highways open."
"One of the measures we are employing to slow traffic down are temporary speed limits which can be employed on parts of the highway network that are most at risk."
The temporary speed limit of 50kmh had been put into effect on State Highway 8 at sites like each side of Lake Tekapo township, and near the Tekapo Military Camp, the Tekapo Flyover (over the Tekapo Canal) and Simons Pass.
Mr Pinner said "This is not our usual approach, but the nature of the conditions forecast for this week means we need to use every tool we can to keep people safe on the roads."
"Our typical de-icing agents are at the extreme range of where they aren’t as effective, and while we are gritting the roads, driving to conditions is a key part of keeping road access safe also."
"If the conditions warrant it, we will close the highway, most likely overnight and through the high-risk early morning period. People need to plan ahead if they are travelling in the area — keep an eye on our Journey Planner site."
These precautions came after last week’s closures of State Highway 8 in the Mackenzie Basin.
He said at the time: "With the snow continuing to fall and roads becoming extremely icy at nights, our teams made good calls to do some overnight closures between Fairlie and Twizel in recent days."
Mr Pinner said, "While we know these closures can be disruptive for some, I have no doubt that those decisions helped to prevent accidents and stranding of vehicles that could have led to much longer closures and even greater disruption. We know this because we have already had to deal with stranded and crashed vehicles in the last week, as people were caught out by the weather and road conditions."
He said: "Preventing travel when the risk is at its highest also means less risk posed to emergency services that get called in to help when something goes wrong."
"Closing down the highway overnight enabled our crews to work around the clock safely, to remove snow and de-ice, grit the roads, and then to lead vehicle convoys at controlled speeds through the affected stretch of highway to allow reopening."
"Our crews have done some outstanding work on SH8 and other South Island highways over the last week to minimise the impacts on motorists and residents."
Key considerations for winter driving include adjusting speeds to suit the conditions, being visible, increasing following distances on slippery roads and avoiding sudden braking or turning movements.
"Winter has only just begun and we know there will be plenty more weather events to deal with. If everyone plays their part, then it makes life easier for all of us."
More winter driving advice could be accessed at www.journeys.nzta.govt.nz/journey-planner
— APL
