Of course it goes without say that Lemoyne Junction was protected by one of many interlocking towers along the PRR system. Built in 1885, J tower (later named Lemo) was situated in between the Cumberland Valley and Northern Central to protect the at grade crossing of the two lines in Lemoyne, Pennsylvania. The tower originally controlled switches and signals using a 35 lever mechanical machine (armstrong levers) linked to cranks and pulleys that moved the switches out on the line, subsequent upgrades modernized the interlocking plant using the standard Union Switch and Signal Model 14 electro-pnuematic plant. One of only two surviving examples of the early PRR standard design wood frame interlocking towers (the other variation being Shore Tower on Amtrak's Northeast Corridor) this tower was functioning up until the early 1980s under Conrail when the tower was removed from service. A group of volunteers with the Lancaster Chapter of the National Railway Historical Society saved the building, disassembling the structure and securing a location at the Strasburg Railroad where it would be reassembled and restored to its original appearance. In addition to the building's exterior restoration the interior would be reconstructed to its original operating configuration including the armstrong mechanical plant, parts of which were graciously supplied by Amtrak from Brill Tower in Southwest Philadelphia. Today people young and old can tour the building to gain a unique perspective of a facet of railroading that has largely disappeared in the computer age.
Here is a great little photo essay on Lemo Tower by photographer Jim Bradley