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Monday, July 16, 2012

Hoboken Terminal Tower and North American Panel Interlockings

In 2005 the door closed on one of the last large panel driven interlocking tower in North America.  Occupying the bridge between second generation power interlocking machines like the Model 14 and Pistol Grip and today's ubiquitous computer driven interlocking systems.  Typically referred to as N-X interlocking machines, the simple technology of pushing buttons to set routes is just one part of a true panel interlocking. The best example of panel machines controlled either large territories or complex stretches of track.  In addition to the simple N-X route buttons and unit levels for switches panels would be outfitted with communications equipment and large analogue model boards separated from the human interface that would light up the routes set.  Sometimes this interface would be simplified like a GRS TrafficMaster, other times a highly compact model board that could be easily reached by the operator, but no matter their appearance their time in service was short lived.

Panel type interlocking control systems were never as popular in the United States as they were in Europe or other parts of the world. At the time that large panel type technology replaced power frames like the US&S Model 14 and GRS Pistol Grip (~1955-1985), railroads in North America were entering a period of sharply declining fortunes and austerity. Where lines retained their signaling or were not simply ripped out, classic interlocking towers dating from the 1900's through 1940's were either not replaced or replaced by Unit Lever CTC type panels, which while a form of panel, completely lacked the sorts of advanced technologies seen in European panel boxes. While there was adoption of first generation N-X technology for complex junctions and terminals starting in the late 1930's, this petered out austerity took over and railroad's physical plants were drastically simplified along with the near complete abandonment of passenger operations where the need for advanced panel technology would be greatest.

The other factor working against large panel type "boxes" in North America is the fact that vital interlocking hardware for large areas is not concentrated in one structure and the lower traffic density, even in remaining passenger terminals, was never high enough to necessitate things like automatic train describers. Therefore what panels were built served only as a human interface device, one that was easily replaced by software solutions and video display units. While most railroads jumped directly from towers to computers or from first generation CTC panels to computers, there was a small period of time where N-X panels with all the flashing lights were standard fare in dispatch offices and those towers that remained open. Here is a YouTube video of one such panel, situated in RU tower in Lorain Ohio that also happened to be a lift bridge control cabin, in operation. 



The other problem was that when railroads did rebound after deregulation in the 1980's those that had previously made the largest investment in signaling were the roads serving the heavily industrialized northeast and Midwest. When manufacturing was decimated those railroads found their signaling and track infrastructure drastically overbuilt just at a time when new technology was appearing so those few panels that had been installed in the late 50's and 1960's were nearly all removed from service during this period. Here are videos of two examples on the former Reading System in Reading, PA. The first is VALLEY tower which contained a wrap around General Railway Signal N-X console dating from the 1950's which had the operator directly pressing buttons on the model board. The machine is on the verge of retirement here in this 1987 video and you can see how much of the physical plant has been altered by looking at what's been blanked out on the diagram.



 Across the river from VALLEY is OLEY tower, which was built in the 1960's to consolidate several older towers in the Reading terminal and yard area. OLEY was provided with a much more advanced N-X setup that had a billboard style model board sitting in front of a wrap around operator's console. In this case the operator would work compact groupings of N-X controls on miniature diagrams, but not interact with the model board itself. In a similar 1987 video we can see the inside of OLEY shortly before its closure as part of the same re-control project.



So this brings us to Hoboken Terminal Tower which was built along with the terminal itself by the Delaware, Lackawanna and Western in 1907. As can be seen in the Signalbox site's page the original tower, which had the appearance of a gingerbread house, contained an ancient 155 lever US&S Electro-Pneumatic type interlocking machine. This machine was in service up until the early 1980's when the state took over commuter rail operations directly from DL&W successor Conrail, which had previously been running them under contract. The old DL&W commuter rail system was in a sorry state to say the least with the 1907 signaling running electric MU's dating from 1930 under a bizzare signal aspect system. The state planned to replace both the aging 3000 volt DC electrification and completely re-signal the lines with modern signals displaying standard signal aspects. Most of its new commuter lines were to be signaled from a new dispatch office inside the Hoboken Terminal headhouse utilizing large non-video type model board displays. However the complex Hoboken terminal would still be worthy of its own dedicated interlocking tower and for this purpose a new 4 story brick structure was constructed at the end of the longest platform with a mix of signal operators and clerks contained within.


However 21 years later the entire 1984 vintage signaling control system with its micro-bulb lit model boards and semi-computerized operation was already starting to show its age and compared poorly with new all software systems that could do things like train description. Even more of a concern was the fact that with the office in the terminal station, signalers might occasionally interact with train crews, contaminating them with non-management approved ideas. Therefore the decision was made to move the whole kit and caboodle to a new control center located in the isolated Meodowlands Maintenance Facility, affectionally named Club Med due to all of the creature comforts the new facility would have compared to the old one. In addition to the dispatch center it was determined that having signalers who could actually see the complex terminal they were responsible for was a bad idea that might complicate scheduling and management so instead of replacing the old Terminal Tower hardware with some computer screens those jobs were also moved to Club Med.

Anyway what inspired this entire post is that I finally discovered some photos of the inside of Terminal Tower, which also happened to be taken on its last day of service on June 10th, 2005. So let's begin by entering the operational area of the tower.




Walking into the tower we see both the model board and the operators' console which has two positions, one for the West and East End interlockings and one for the terminal trackage itself. The terminal itself had 18 tracks arranged in two sections, north and south. West of the terminal platforms there is a large storage and light maintenance facility with main tracks running around it on either side. South section platform could only be reached via the pair of main tracks to the south of the yard and North section tracks via the tracks to the north of the yard. There was some overlap and the north section was much larger than the south. Where all the main tracks came together west of the terminal interlocking was known as East End Interlocking and used to have its own local tower, the base of which is still visible. Here the 4 main tracks are established and then continuing to the west the line passes under the Bergen Hill via a pair of two track tunnels. Right at the western portal of the tunnels is West End interlocking where a number of diesel only lines diverge from the electrified lines in a 4x4 flat junction that also has a single wye track with crossovers west of the split. This too had its own local tower in the pre-1983 configuration.

I had also heard that by time point NJT was controlling several of its movable bridges via CCTV from the Terminal Tower building as well, but I d not know where the tenders would have been seated.



Here we see the position for the West End and East End interlockings.  Control is provided through two miniature N-X panels of GRS design.  There are few status lights on the control panel themselves, with the operator expected to look up at the big board.


Here is a closeup of the East End panel showing the blocks of unit switch levers on either side and the N-X push buttons on the panel itself.  The N-X buttons had all of the usual features including fleeting and locking out of routes.


On the far right is the Hoboken Terminal control station with its extra large panel handling the 20 some odd tracks and significant yard and storage facilities.  Again note the large block of unit levels to set and lock individual switches outside of the N-X logic.  This was the only panel still functioning at the time of the Tower's closure and even then only the north side of the terminal was still under its control.  Note the blocking devices still applied to certain route buttons and unit switch levers.  The CRT is a train describer to inform the operator which train is due out of which track.


Here we see the operator's eye view of the large model board.  Again only the north end of the terminal trackage itself is still under control of the tower and hence, still lit up on the board. 



Here is a closeup of the board itself.  The tracks were lit by a series of small lamps, probably miniature incandescent, with red indicating  track occupancy and white indicating a lined route.  A flashing white line would show when a route was in the process of being set up.  it isn't hard to imagine the imazing complexity that underlaied this system with all sorts of miniature wire wrap relays driving the logic.  Its no wonder that such complicated and proprietary equipment was substituted with software.


It would not be right to leave terminal Tower without a vision of what replaced it, shown here 4 minutes before the end of the tower's last shift.  With most of its territory now dispatched from Club Meadowlands Maintenance Facility, display screens were provided in Terminal Tower to assist the operator in routing traffic out of the last remaining territory.


New Jersey Transit was hardly alone in taking this path of signaling evolution. The Philadelphia area commuter rail operator, SEPTA, also did a lot of re-signaling with panel control in the 1980's to compliment a large N-X panel project carried out by the Reading before SEPTA took over. However in 2003 SEPTA closed its panel towers and consolidated control in a downtown dispatch office with VDU wall screens. The last major North American panel setup installed for railroad use was the ~1994 Metro North re-signaling of Grand Central Terminal where non-video display model boards were paired with miniature push button interfaces for the dispatcher to operate. Three such positions were provided, one for each of the three former towers that controlled GCT. These were in service until just a year or two ago when the whole dispatch office was converted to a video wall format. When Penn Station undertook a similar process of replacing its old towers a large N-X panel was constructed as a backup in case the computer system failed, but it is not in daily use. Finally when the interlocking towers covering the south side of Chicago Union Station were closed, control was moved to LAKE ST tower on the north side of the station in the form of a huge 3-4 person panel of US&S manufacture. This too was taken out of service when the whole area was re-signaled in 2005. Today the only user of traditional panel type interfaces are rapid transit systems like the CTA in Chicago and NYCTA in New York City. Of course most if not all field interlocking locations have a local control panel, but I don't think that really counts.

Anyway I hope you enjoyed these photos as much as I did. They are a rare find and the first photos if the inside of Terminal Tower I have ever come across. If you enjoyed them I urge you to check out the rest of the author's work.

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