Slippery spot clues — New Mexico Permit Test

On cold, wet days shady spots can be icy; they freeze first and dry out last.

Shade keeps the sun off the road, so ice there can linger after the rest of the road is clear.

On cold, wet days shady spots can be icy.

Bridges and overpasses can be icy when other pavement is not, because they have no earth underneath to insulate them against the cold.

Cold air hits a bridge from above and below, so it freezes before the road leading to it.

This is because bridges do not have earth underneath them to help insulate them against the cold and thus can be colder and icier than other roadways.

When the temperature is around the freezing point, ice can become wet, making it more slippery than at temperatures well below freezing.

A thin layer of water on top of ice makes it slicker than hard, dry ice.

When the temperature is around the freezing point, ice can become wet.

If it starts to rain on a hot day, pavement can be very slippery for the first few minutes because heat brings oil in the asphalt to the surface.

The first rain mixes with oil on the road, and it stays slick until the oil washes away.

If it starts to rain on a hot day, pavement can be very slippery for the first few minutes.

On a cold, wet day, which part of the road is likely to be icy?

Shady spots on the road. Shade keeps the sun off the road, so ice there can linger after the rest of the road is clear. New Mexico Driver Manual, p.20: “On cold, wet days shady spots can be icy.”