Photographs & History

Photographs and History

State Interlocking

Plate drawing circa 1963 illustrating the territory of State Interlocking, which is still controlled today by the original Union Switch and Signal Model 14 interlocking machine. Plate drawings collection of "The Broad Way" website 

Plate drawing circa 1963 illustrating the territory of State Interlocking, which is still controlled today by the original Union Switch and Signal Model 14 interlocking machine. Plate drawings collection of "The Broad Way" website 

On the south end of the Harrisburg Passenger Station, tucked away in a two-story addition dating back to the final phase of electrification in 1937 two significant PRR facilities operated around the clock. State Interlocking Tower is on the far south end of the station building and originally controlled the east end operations of the passenger terminal, access to the Cumberland Valley line to Hagerstown and the Northern Central via Lemoyne Junction on the West side of the Cumberland Valley Bridge. In addition to these important mainline connections State also controlled the Columbia branch that comes up from Royalton as well as access to both PRR and Railway Express Agency warehouses that handled local express traffic off the passenger trains.

Detail of current State Interlocking US&S machine and model board. Compared to plate drawing above note home much trackage has been removed including connection to the Columbia Branch, Reading interchange (now NS Harrisburg Line) and Cumberland Valley Line (lower center segment). Inset below shows the existing State Interlocking including operators desk and one of three additional remote interlocking modules added after the original installation.

Detail of current State Interlocking US&S machine and model board. Compared to plate drawing above note home much trackage has been removed including connection to the Columbia Branch, Reading interchange (now NS Harrisburg Line) and Cumberland Valley Line (lower center segment). Inset below shows the existing State Interlocking including operators desk and one of three additional remote interlocking modules added after the original installation.

Harrisburg_Terminal_07

Opening in 1937 as part of the terminal electrification, State Tower contained a standard Model 14, Union Switch and Signal unit, customary in most PRR interlocking towers. The interlocking was operated in conjunction with Harris to coordinate the combining and splitting of passenger trains in the station while also facilitating engine changes and yard moves needed to maintain passenger operations. While State still operates as a local block and interlocking tower, the physical plant is not nearly as intricate as it once was. Since traffic no longer operates on and off the Cumberland Valley Bridge and Norfolk Southern makes no connection from the Columbia Branch at the passenger station, most operations focus on  Amtrak trains arriving and departing for Philadelphia. Occasionally a bad order coach or cab car will be switched out here or turned on the wye but typically operation is pretty straightforward. Several responsibilities were added to State’s territory after Roy and Harris were decommissioned, giving State the remaining control of the NS connector at Capitol Interlocking (just west of Harris) and Roy interlocking where the NS Columbia branch diverges off the mainline further east in Royalton.

Looking east across State interlocking from the pocket track on the #3 platform. Note the Norfolk Southern train holding the Royalton Branch (called Columbia branch in PRR days) which connects to the former Reading line now utilized by Norfolk Southern.

Looking east across State interlocking from the pocket track on the #3 platform. Note the Norfolk Southern train holding the Royalton Branch (called Columbia branch in PRR days) which connects to the former Reading line now utilized by Norfolk Southern.

Also part of the 1937 construction, the Harrisburg Power Dispatcher’s Office was constructed to monitor and control electrical supply and loads on all electrified territory from Harrisburg and Enola east to Thorndale on the main and low-grade routes and south to Perryville. This facility survives as an incredible symbol of the strides the PRR made in electric traction technology and remains intact although not in use. The facility is still occupied by Amtrak’s power dispatcher who now works from a computer terminal in the center control atrium of the original installation. When visiting the facility last fall there was discussion of this location closing with completion of Amtrak’s new CNOC pending, but to my knowledge the facility is maintained to date. The Harrisburg facility was one of three such installations on the PRR with the other two at 30th Street Station in Philadelphia and the Service Plant building of Penn Station in New York City, neither of which are still intact.

Panel detail of Power Dispatcher's Office in the Harrisburg Passenger Station. This impressive installation dates back to the 1937 electrification to Harrisburg and was responsible for monitoring and controlling electrical loads and supply from Thorndale and Perryville west to Harrisburg. Along the three walls the entire mainline system is illustrated noting substation installations and interlockings, accompanied by indicator lights for the status of both train and signal power. In the foreground are control panels that correspond and essentially functions as breakers for all circuits, phase breaks, and sub stations. This would be a stressful place to work during inclement weather as dispatchers worked against ice, lightning and heavy winds to maintain power to keep trains moving in adverse conditions.

Panel detail of Power Dispatcher's Office in the Harrisburg Passenger Station. This impressive installation dates back to the 1937 electrification to Harrisburg and was responsible for monitoring and controlling electrical loads and supply from Thorndale and Perryville west to Harrisburg. Along the three walls the entire mainline system is illustrated noting substation installations and interlockings, accompanied by indicator lights for the status of both train and signal power. In the foreground are control panels that correspond and essentially functions as breakers for all circuits, phase breaks, and sub stations. This would be a stressful place to work during inclement weather as dispatchers worked against ice, lightning and heavy winds to maintain power to keep trains moving in adverse conditions.