Carmageddonin' It? In a photo from last year, a traffic signs alerts motorists on Interstate 405 that the freeway will be shut down for two days in July for demolition of the Mulholland Bridge. The city is bracing for Carmegeddon II, scheduled for this weekend. Kevork Djansezian/Getty Images hide caption

itoggle caption Kevork Djansezian/Getty Images

Dr. Mitch Katz rides his bike to work, defying the commuting norm in Los Angeles. Michael Wilson/L.A.County Health Services Dept. hide caption

itoggle caption Michael Wilson/L.A.County Health Services Dept.

Miramonte Elementary School in Los Angeles. Krista Kennell /AFP/Getty Images hide caption

itoggle caption Krista Kennell /AFP/Getty Images

Back on the road: Traffic on a 10-mile stretch of I-405 in Los Angeles started flowing on Sunday, nearly a day earlier than planned. Kevork Djansezian/Getty Images hide caption

itoggle caption Kevork Djansezian/Getty Images