Crozet's inverted-tub ventilation system

A 4,273-foot tunnel through solid rock, in the steam-locomotive era, posed a problem most people did not think about: smoke.

A coal-fired locomotive in a long tunnel produced enough smoke and noxious fumes to suffocate the engine crew and passengers. Crozet engineered an inverted-tub ventilation system, a series of arched ductwork that channeled smoke up and out through ventilation shafts cut into the mountain.

He also laid roughly 2,000 feet of cast-iron drainage pipe to manage groundwater seepage from the rock. The ventilation worked. Trains passed through the Blue Ridge Tunnel for 86 years.