Wildfires are a growing risk in the western United States, as demonstrated by the 2018 Camp Fire in northern California, and last-minute evacuations increase dangers by straining transportation systems.
Residents who didn't receive or heed warnings faced increasing hurdles making it to highways, said CAEM professor Yi-Chang Chiu, a transportation engineer who studies evacuations. "They will have a hard time getting out, and these are the most vulnerable people because they are at the end of the queue."
Many small communities offer only a single escape road. Under ideal conditions, a single lane of free-flowing traffic can accommodate 1,800 vehicles an hour. With stop-and-go traffic – more vehicles turning at intersections and oncoming emergency vehicles – the number drops below 500 vehicles an hour.