Commuter rail is something like Chicago's Metra, with Amtrak-like trains and stops far enough apart that walking is out of the question. Elevated trains and su

Commuter rail is something like Chicago's Metra, with Amtrak-like trains and stops far enough apart that walking is out of the question. Elevated trains and subways in Chicago and New York can and do act as light (not commuter) rail with stops every few blocks.