Throughout my travels, I frequently find myself fascinated with various types of railroad engineering. During my five years at Amtrak, I got the chance to observe quite a few distinctive machines devoted to the process of building railroad tracks. Particularly memorable were Portal-Krane 1, which maneuvered large pre-constructed switches into position during Penn Station Renewal, the catenary maintenance cars that lift technicians into position to service the wires on the Northeast Corridor, and the various rail grinders and welding machines used to replace Continuous Welded Rail (CWR). Closer to home but in a similar vein, Metro-North’s rail train has recently...