At what temperature does an icy roadway provide the least traction?

An icy roadway provides the least traction between 30 and 32 degrees Fahrenheit. This is the critical temperature range where ice can begin to melt slightly, creating a thin layer of water on the surface, which acts as a lubricant. This layer reduces the friction between the tires and the road, drastically diminishing traction and increasing the risk of skidding.

When temperatures fall below 30 degrees Fahrenheit, the ice remains more solid and may not have the same slippery layer of water, leading to greater traction, albeit still potentially hazardous. At freezing point (32 degrees Fahrenheit), it is a transitional phase where conditions can fluctuate, but the danger of slippery conditions is generally heightened just before the complete freezing or thawing occurs. Thus, the period between 30 and 32 degrees is particularly treacherous for drivers as the ice can be very slick due to this unique combination of conditions.