Los Angeles is no stranger to big disasters -- massive earthquakes, riots, Lindsay Lohan. But closing a 10-mile stretch of freeway for 53 hours, as the city will do on Interstate 405 this weekend for a bridge demolition? That's a different matter entirely. It's Carmageddon. To help outsiders understand how a freeway shutdown could evoke such dread, the L.A. Department of Apocalyptic Scenarios has prepared this guide to the most frequently asked questions.