Penn Tower interlocking machine

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Penn Tower is located on the fourth floor of 30th Street Station in Philadelphia. The machine is an Union Switch and Signal CTC-style case, although the entire interlocking is direct-wire control. The relay room is located above the tower, with an access door on the fifth floor of the station. At the time I took these photos, Penn also controlled Phil interlocking, located south of Arsenal in southwest Philly, until CETC assumed control of that interlocking in 1991.

Penn machine. The Phil machine is at the left; turning further to the left would show a table on an elevated platform. The train director and the "goat" (assistant to the train director) sat at the table while the leverman sat at the machine. Since these pictures were taken during a third trick with only a train director on duty, the train sheet is down at the machine -- and the radio microphone is sitting on the platform floor just out of sight. The phone on the machine desktop is for the block line; the Bell phones are located on the director's table and on a stand just out of sight to the right of the interlocking machine.

Left side of the Penn machine. Along the desktop: the two toggle switches with indicator lights are the low air alarms for the south end of the interlocking (60 pounds and 25 pounds, if I remember correctly). The block phone patch panel is inactive. The 8x3 panel of buttons are the trolley indicator switches; pull them out to turn the "cherries" on. On the extreme right, the panel of pushbuttons and lights are for the train ready indicators; at one time, there were indicator lights and buttons located at platform level which conductors would use to signal Penn that they were ready to proceed, as well as indicator lights on the concourse level that indicated to the station personnel that a train was approaching on a given track. The only part in use at this time were the station "tap" lights, one for each track: when a train was on the approach circuit, we were supposed to push the button that turned the light on, indicating that the train was about 4 minutes out of the station; once a train departed, we pushed another button that extinguished the light. The station lights are located on the south wall of the main concourse, just above the destination boards, one for each track -- they are no longer in use.

Above the items I just described, are the levers for switches, signals, and check levers. Switch levers are on the top row, and very simply swing left or right; no buttons get pushed. THe lower row of levers are for signals; these levers gaan get turned back and forth with no results... until the lever is pushed in -- that activates the circuit. The buttons beneath the signal levers are the "call-on" buttons, which will display a signal into an occupied block. The ten levers to the right side are check levers, one for each of the ten station tracks. These worked as pseudo-traffic levers: in order to display a signal into an unoccupied station track, the check lever had to be swung in the direction of travel. Once the track was occupied (after a ~three minute timer ran), the check lever had to be placed on center, which allowed a signal to be displayed into the track from either direction. This permitted switching moves to be made, but prevented putting two trains in on the same track from both ends of the station.

Right side of the Penn machine. Items along the bottom of the machine are mirrored from their description on the left side. Also in this photo are employee timetable and rulebooks, and the train sheet (immediate front); to the left on the desk is a clip holding the station transfer log, which shows what tracks are occupied, and the Form Ds in effect. The block phone can be operated in hands-free mode with the use of a foot pedal to activate the microphone.

Phil machine. This is a General Railway Signal entrance-exit machine. There is a similar panel located in the relay house at Phil. The extreme outer buttons on the track diagram are panel blocking devices; the inner buttons are used to route traffic. Unlike other GRS NX installations I've seen, this was set up so that, after punching in the desired entrance and exit points, the entrance button had to be pressed again to request the signal. The levers below the track diagram are for manual switch control; they are normally on center, but can be swung left or right and activated with a pushbutton. Toggle switches to the lower right are for the trolley de-energized "cherries". Toggles midway on the left side of the machine are for switch heaters and maintainer call horn; toggles in the lower left are dragging equipment detector resets. The lever and button above the trolley toggles is for local/remote control of the interlocking. Normal position is "remote" as Penn has control; local control is assumed at the panel located in the relay house.

Phil machine close-up. Tracks on the left are (from top to bottom): SEPTA Airport Line, No. 4 Main, No. 3 Main, No. 2 Main, No. 1 Main, and Escape track for the Airport Line. Tracks on the right side are (from top to bottom): No. 5 Main and No. 4 Main to Arsenal, No. 3 Main and No. 2 Main to Penn, No. 2 Arsenal Connection and No. 1 Arsenal Connection; the Arsenal Connection tracks are part of Conrail's Harrisburg Line. The Conrail tracks are shown dashed to indicated non-electrified tracks. Indicator light colors are: white for track occupancy, yellow for switch position (flashing switch is out of correspondance), red lights are the cherries. The red LEDs in the lower signbal heads turn green when a signal is displayed; the upper head is illuminated with the signal is fleeted.

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