SEPTA and the City are testing a new traffic signal at the corner of 15th and Market streets designed to give buses a three-second head start over traffic. It's called a "queue jump signal."  Officials hope that bringing the signals to busy bus corridors will help improve service and ease congestion in Center City. 

Starting this month, SEPTA drivers approaching 15th and Market in the bus lane heading eastbound heed to the new LED traffic signal, which uses a white bar that tells them to stop or go. Drivers know to brake when the bar is horizontal and move again once it switches to vertical. Drivers have three seconds to forge ahead into the intersection before the green light blinks on for other vehicles. The three-second head-start is enough to prevent buses from getting blocked in by other vehicles at the intersection.