HARRISBURG, Pa. – With a cellphone, tablet or notebook in hand, visitors can activate a Pennsylvania Railroad position-light signal here to replicate any of 19 indications, past or present, used to govern train movements.
The Harrisburg Chapter of the National Railway Historical Society on Wednesday (Feb. 19) completed a project, years in the making, that gives visitors digital control of a two-target Union Switch & Signal Co. signal. At 18 feet high, it stands on the grounds of the chapter’s ex-PRR Harris interlocking tower, two blocks north of Amtrak’s Harrisburg station.
The project required hundreds of hours of writing code to enable a microprocessor interface to translate commands from any mobile device – Android or Apple – into real-time signal displays. Thousands of US&S position-light signals served on PRR – for which they were developed in 1914 – and successors Penn Central, Conrail, Conrail Shared Assets, Norfolk Southern and the Philadelphia commuter agency, Southeastern Pennsylvania Transportation Authority. Other carriers using the design included Pennsylvania-Reading Seashore Lines, Long Island Rail Road, Chicago Union Station, Norfolk & Western, and Union Railroad.
Position-light fixtures served as home signals at interlocking plants, as distant signals (in advance of interlockings), and as intermediate signals (automatic block signals).
While Class I freight roads that used them have largely retired them, they remain active on Conrail Shared Assets, SEPTA and LIRR. Amtrak’s Northeast Corridor and Keystone lines employ a variation that adds red and green lights. Position-light signals originally used all yellow bulbs, later modified in some areas to add red for “stop signal” indications at interlockings.
In the chapter’s installation, users choose between all possible combinations for either classic PRR signals or contemporary types codified in the NORAC (Northeast Operating Rules Advisory Committee) rulebook. In all, 16 lights can display 19 combinations of vertical, diagonal, or horizontal rows of lighted bulbs, which were designed to mimic the positions of the movable semaphore blades they replaced.
“With signaling being so integral to railroad towers, this fully functioning PRR position-light home signal . . . will now bring the PRR’s most iconic signals to life for future generations,” said Harrisburg Chapter president Mark Eyer. It will, he said, “help us to tell the complete story of what was involved in being a railroad tower operator. Using today’s technology [will] bring railroading to life for all visitors. To my knowledge, there is no other operating signal like this one.”
Operators at Harris once controlled 106 signals, most of them dwarf signals, and 87 switches, handling more than 100 passenger trains and 25 freights a day. Because it stood at the western end of PRR’s electrification, the tower also governed the swap of locomotives from electric to steam, and later, diesel engines.
Assembling components
The project began more than six years ago when John Smith, former chapter president, proposed a display and began gathering parts, some purchased and some donated. Among the components are pieces from PRR’s 21st Street tower in Chicago and from Port Deposit, Md., on the Columbia & Port Deposit Branch, the latter items purchased from the West Chester Railroad. Metal pieces were cleaned and painted or powder-coated.
Board member and Curatorial Committee Chairman Andy Ottinger agreed to oversee the mechanical aspects of assembly – a tangle of pipes, bolts, lamp boxes, visors, brackets and clamps – while Dan Rapak agreed to take on the wiring and electronics. Rapak had earlier headed a computer-driven project to enable Harris Tower’s 113-lever interlocking machine to offer an interactive experience. It allows visitors to direct a simulated train through the plant on the schedule of a typical day in 1943.
The committee considered several methods for illuminating the signal and varying its aspects as an educational exhibit, but each posed maintenance, weather or visibility obstacles. Finally, in March 2024 Rapak contacted Joseph Anderson, a computer programmer who developed the popular TrainMon5 online tracking app, to investigate a mobile-device-based web software solution. Anderson agreed to donate his time, and wrote the web program. Rapak built a microprocessor interface that is housed at the tower and wrote its associated code.
Original replacement bulbs were becoming scarce, so the chapter opted to use low-voltage LED lights that replicate the intensity and directional focus of the original.
The electrical side of the project was completed last August, in time for visits by NRHS members attending the group’s 2024 national convention. Further work stabilized the mast, which with all devices weighs 1,000 pounds. The remainder of tasks – positioning and bolting together the ladder, platforms, and masks (52-inch-diameter steel plates to prevent stray light from giving a crew a false signal reading) – wrapped up this week. A finishing touch will be the addition of a four-light dwarf signal, which also will be controllable from a mobile device.
The jobs of digging a cable trench, positioning the mast with a crane, and mounting the hardware were handled by an excavating contractor. Arney Brothers, Inc., of Harrisburg donated all of the staff time and vehicles needed at each step to completion.
Hand-held control
Visitors can scan a QR code displayed on a sign mounted near the signal, which opens a web page on their device. No password is needed. From there, a menu allows a person to choose the signal to be displayed and learn the rule number, name of the rule and the indication (action required by the train crew).
A timer limits access to 5 minutes if another user is waiting. When a visitor exits the program, the lights extinguish a few minutes later.
Opened in 1930, Harris Tower controlled all of the switches and signals at the west or north end of the 1887 PRR passenger station, which in its heyday handled trains to and from five main lines. Amtrak closed the tower in 1991 and sold it to the chapter a few months later. It is listed on the National Register of Historic Places, and the chapter staffs it for public visits on Saturdays June-October. Although it’s closed for the winter, anyone visiting the site can operate the position-light signal at any time. The tower’s next open house will be held during the chapter’s annual train show on March 8.
Wonder if the group had to secure permission from AMTRAK for this trackside project.
Love those PL signals! Cut thru the fog like a knife!