In the winter, when Interstate 70 shuts down at exit 205 due to car crashes or a deluge of snow, Silverthorne police chief John Minor gives his officers the same piece of advice: “You better have your head on a swivel and your head in the game, because it’s about to get a little sporty.” For the officers and state patrollers who ride herd over the chaotic cattle drive of cars and semis during an interstate evacuation, being on high alert means the difference between life and death. “If you’re actually on the interstate staffing that closure just before the...