OAKLAND, CA - OCTOBER 21: Traffic backs up on Interstate 80 at the San Francisco-Oakland Bay Bridge as the Bay Area Rapid Transit (BART) strike snarls the Monday morning commute on October 21, 2013 in Oakland, California. BART workers continue to strike after contract negotiations between BART management and the transit agency's two largest unions fell apart last week. Management and unions agreed on the financial specifics of the contract but differed on workplace safety rules. An estimated 400,000 commuters ride BART each day. (Photo by Justin Sullivan/Getty Images)OAKLAND, CA - OCTOBER 21: Traffic backs up on Interstate 80 at the San Francisco-Oakland Bay Bridge as the Bay Area Rapid Transit (BART) strike snarls the Monday morning commute on October 21, 2013 in Oakland California. (Photo by Justin Sullivan/Getty Images)