Mayor Antonio Villaraigosa was taking his first ride Monday on the Metro Orange Line to promote safety around the busway when suddenly the driver hit the brakes, narrowly avoiding a motorist who apparently ran a red light at Kester Avenue. It was a real-life, real-time example of what officials are seeing repeated across the San Fernando Valley as buses practice for Saturday's opening. For the mayor and others on board, it underscored the need for motorists and pedestrians to be careful. "For San Fernando Valley residents who've waited for their share of transportation improvements, the Orange Line is a down...