Roadways are the most slippery:

• A. The middle of a heavy rain
• B. The first rain after a dry spell
• C. After snow melts
• D. At night

Answer: (B)

Traction is at its lowest when rain first arrives on a dry road. On a road that has been dry for a while, oils, greases, and dust from traffic build up on the surface. When the first rain hits, that coating is wetted and mixes with the water, creating a very slick film that drastically reduces grip. As rain continues, that film starts to wash away, and the road grips improve. The other scenarios can be hazardous for different reasons—heavy rain can cause hydroplaning due to standing water, melted snow can leave wet or icy patches, and nighttime mainly affects visibility—but the initial rainfall after a dry spell is the time the surface is typically the slickest.