A quiet misty night. The air is still as masses of fog gently drift over the towers of the Ben Franklin Bridge. The pedestrian path is nearly abandoned in these cold unpleasant conditions. The walkway begins to rattle, the tracks become illuminated by approaching headlights, and the sound of metal screeching on metal crescendos as the PATCO train bolts across the tracks towards Center City Philadelphia. Once it has passed, tranquility is restored until the next train comes. The rhythm of the Ben Franklin Bridge.