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The New Zealand Transport Agency will be hoping for some sub-zero temperatures this winter, as they again trial a new ice warning system in Otago.
Contractors were yesterday installing the PATeye markers, designed by Christchurch firm Solar Bright, on Dunedin's Northern Motorway.
The markers incorporate a sensor which tracks the ground temperature. When it drops to a certain level, the blue LED lights start flashing.
They were trialled in 2012 in Northeast Valley and Sunnyvale, and by the NZTA on Otago highways last year.
But an NZTA spokesman said last year's trial was not successful, as the winter was not cold enough.
NZTA Otago-Southland state highways manager Ian Duncan said the latest trial would look at the effect of the markers on driver behaviour.
It would study whether drivers slowed down when they saw the markers, and motorists would also be surveyed on what they thought of them.
Depending on how the trial went, it might be rolled out elsewhere around the country, Mr Duncan said. The technology could also help road crews more effectively target areas on which to lay grit to help make icy roads safer. Ultimately, that would help reduce winter road maintenance costs.
Other trials will to be held on State Highway 1 at the Taieri River Bridge, SH8 at the Manuka Gorge, and SH1 just north of Milton.