Boise, ID – As temperatures plunge into the teens and light snow spreads across the Gem State this season, the Idaho Transportation Department (ITD) is warning drivers in Boise, Idaho Falls, and Coeur d’Alene to watch for icy bridges and overpasses freezing faster than main roads.
According to the National Weather Service (NWS), bridges freeze first because cold air surrounds them from both above and below, pulling heat away quickly. This makes bridge surfaces drop below freezing temperatures even when nearby pavement remains slightly warmer. “That’s when black ice forms, often invisible until it’s too late,” the NWS said Friday.
ITD crews apply brine and salt to key corridors including I-84, I-90, and US-20, focusing on elevated spans, ramps, and mountain passes. Motorists are urged to slow down before bridges, maintain steady steering, and avoid sudden braking. Even a thin layer of ice can cause vehicles to lose control, especially in rural or shaded areas where sun exposure is limited.
Drivers can check live travel conditions through 511.idaho.gov or follow @IdahoITD for statewide winter road updates and alerts.
