Back in the day, the big "S" curve in Waldwick, NJ was a favorite haunt of railroad photographers as a steady parade of Erie steam pounded upgrade northbound around the (then) four track curves. Beefy Berkshires hustled time freights headed for Chicago while big, imposing Pacifics did the honors on the long distance passenger trains, interspersed with a steady parade of commuters.
Today the picture is a bit quieter, but there is still a dense commuter operation along with the occasional freight. Here a rush hour express led by an Alstom PL42AC slides through the curve on the way to it's Suffern NY terminus.
Future TPOTDNJ Transit