In this April 25, 2013 photo, stoplights shine red and green at top right as traffic flows on Wilshire Boulevard in Los Angeles. The nation's most congested city has become a model for traffic control. With the flip of a switch earlier this year, Los Angeles became a worldwide leader by synchronizing all of its nearly 4,400 stoplights, making it the world's first major city to do so. (AP Photo/Reed Saxon)