| Built in 1935 and named for the nearby Philadelphia Zoo, ZOO Tower once controlled the interlocking where the PRR's New York to Washington D.C.and Philadelphia to Chicago lines came together. The tower is built of brick with concrete floors and has a peaked slate roof. A 227 lever, Union Switch & Signal Co model 14 interlocking machine is contained on the top floor of the tower. Each of the 135 working levers controlled a pair of switches and signals. The first floor contained the relay room, and the lower level, the air compressor apparatus to operate the pneumatic switch machines. ZOO was typically staffed by seven people. Although its functions and purpose were greatly reduced when Amtrak took control of the NEC, ZOO is still an actively manned interlocking tower. |