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Tuesday, March 12, 2013


When one hears the name BLUE ISLAND in a Railroading context one is most likely to think about truss bridges, a 7 track grade crossing, 4 diamonds and the last Crossing Tower in the United States. Blue Island Junction is near the top of the list of hottest railfan hotspots. Located at the west end of both CSX's Barr Yard and the IHB's Blue Island Yard, many tend to pair it with the previously featured Dolton Junction which sits at the east end of the same yard complex. Like Dolton, Blue Island Junction is also controlled by a manned interlocking tower, although it is seldom seen as it sits on the far side of the river, partially hidden by the 5 truss bridges carrying the B&OCT, Grand Trunk, IHB and Iowa Interstate lines over the Calumet River.

However, there exists another Blue Island tower some 3000 feet from the first. Built about the same time and of roughly the same design, the second Blue Island hides in plain sight on a METRA passenger station platform at the southern end of the former Chicago, Rock Island and Pacific Blue Island Yard on what it today's the METRA Rock Island District. Visible on Google Street View, yet largely absent from the discussion today we will look inside the other Blue Island tower and also wrap up my METRA tower interior series as both the now demolished Lake Street and permanently hidden Jackson Street towers were part of Amtrak owned plants.

The METRA Rock Island district can be thought of as the Harrisburg Line of the Chicago area. While significant portions of the line have been running under CTC for decades now, up until 2010 there were still 4 active interlocking towers between LaSalle Street Station in Chicago and Joliet Union Station. These included the unique Gresham Junction, the increasingly elderly 16th St Crossing, the immaculate UD and of course the forgettable Blue Island.Blue Island is so under appreciated that a simple Google search reveals more photos and information about the abandoned Root Street tower than the active Blue Island tower. It probably doesn't help that Blue Island looks like a yard office is placed rather aloofly from the junction that it controls, but that should not diminish the significance of it and the classic relay signaling plant that it controls.

Blue Island was built about the same time as Gresham Junction as the Rock Island sought to modernize its still busy commuter rail operation out of Chicago. Like Gresham, Blue Island was outfitted with a cutting edge Entrance-Exit panel type interlocking machine, but unlike Gresham it used a more conventional relay design instead of the imported telephone exchange based model found at Gresham. Either way, early N-X systems still needed a lot of physical space for all the hardware logic needed for the route setting and user interface logic came in a three story package seen at other contemporary "panel" towers such as the B&O FN Tower at Patterson Creek, with one floor devoted to the interlocking logic and another for the maintenance of same.

Blue Island tower's original N-X plant consists of the local interlocking (which is officially called WESTERN AVE JCT in the timetable, but I will refer to as BLUE ISLAND as that is what appears on the N-X panel) and two remote plants, INTERCHANGE and ROBBINS. BLUE ISLAND was the western junction between the Rock Island Main Line (Joliet Sub) and the Beverly Branch (Beverly Sub) that took the local path through Beverley Hills that included many additional station stops. The eastern end of the suburban Beverly branch was up at Gresham Junction. BLUE ISLAND interlocking was also the southern end of the Rock Island Blue Island Yard, which today is used partly by the Iowa Interstate railroad as its Chicago terminal and partly by Metra to lay up coaches and MoW equipment. Except for some yard leads joining the Main Line, the majority of BLUE ISLAND interlocking is west of the tower itself.

East end of BLUE ISLAND interlocking showing the Electric Division station and hand throw connection.
 The holdout layout of both platforms works in favor of keeping the tower manned as the operator has direct line of sight to passenger behavior that might put them in conflict with arriving trains.  Here we see the 116 and 114 signals, with the searchlight 114 mast displaying a Clear indication.

Continuing westward one will encounter both INTERCHANGE interlocking and then ROBBINS in short order. INTERCHANGE is the junction of the interchange track leading down to the other Blue Island interlocking and ROBBINS is a complete crossover and west end of the interchange track extension. In this photo we can see BLUE ISLAND's intermediate westbound signals (90, 92), BLUE ISLAND's eastbound home signals (72, 74), the westbound home signal cantilever for INTERCHANGE (56, 58) and way in the distance the westbound home signal for ROBBINS.

Clear signals all the way for an approaching train.
 It is also worth pointing out that the line between Blue Island and UD Tower is equipped with PRR-style 4-aspect cab signaling. As seen in the preceding photo, trains platforming at Blue Island can perform a cab signal test before entering the 20 miles of cab signal territory. This was one of those small train control pilots mandated by the ICC back in the 1930's and 40's that was never allowed to be removed, but also never expanded. With all the money being poured into PTC one wonders why reliable cab signaling systems such as this couldn't have simply been expanded.

 Stepping inside BLUE ISLAND, we see the inside of Metra's Blue Island tower with the CTC console and its operator. Like my other METRA interior photos these were not taken by me and date from the 2005-2006 timeframe. All the inside photos are full resolution so for more detail click on the images or hit the "view image" option if your browser supports it. While the interlocking plant was provided with US&S field hardware, the N-X machine does not appear to be of US&S manufacture. The operator has 9 N-X points to work with spread out from ROBBINS on the extreme left to the Blue Island yard leads on the extreme right. On the console itself manual switch position knobs are on the very top, then what look like fleeting or call-on buttons for signals, then the diagram with N-X buttons and finally traffic levers, point heaters and other miscellaneous controls on the bottom. Also on the left is a fairly modern telephone concentrator in front of the old telephone concentrator that is integrated into the panel.

Looking beyond the N-X console we see the tower's angled air traffic control tower style anti-glare windows, a vintage 1950's GE wall clock and a less vintage air condition unit fitted into a hole in the cinderblock wall with expanding foam. There seems to have been various attempts to upgrade the lighting which clash a bit with the aging ceiling tiles and N-X console.

Here we see a closer view of the right side of the N-X panel showing a train moving through the BLUE ISLAND plant from the eastbound main track to the eastbound Beverly branch over the 73, 83 and 103 switches. Like most North American interlocking panels with illuminated tracks this one uses the White-Red system with White lights indicating a lined route and Red lights indicating track occupancy. In this case the eastbound train has just passed the 74 signal and crossed onto the circuit covering the 73 switch. The remainder of the route lit with white lights through to Beverly track 1. There is also an occupied track circuit on the station stub track that follows the normal route off the 103 switch.  During peak periods, Beverly trains terminate at BLUE ISLAND, with the third track between BLUE ISLAND and INTERCHANGE being used to store trainsets.

View westbound down the disused stub track.
 Looking at the top row of switches we can see that a number of switch positions have been blanked out, but there is no obvious indication on the console display where they were located.  Also on the bottom row at the far right of the panel are grade crossing controls for each of the 4 tracks which can override the automatic crossing operation to prevent long waits for motorists for trains making station stops (and cab signal tests) at the Blue Island station.

Sitting on top of the original N-X console is a supplementary Unit Lever CTC machine that controls two additional interlockings on the Beverly Branch. The first is 125TH ST, which consists of a single facing point crossover at the entrance to ABS/Dark territory. The second is VERMONT ST, which is actually adjacent to the Blue Island Station and tower and controls access into the METRA coach/MoW yard. However VERMONT ST is interesting as it consists of controlled signals with hand-thrown switches, as can be seen here in this Google street view. The Unit Lever panel has standard controls for the 125TH ST plant with two signals, 20L/R and 18L/R, and a single switch, 19, but the VERMONT ST plant is a bit non-standard and I can't quite tell what all the buttons do except two appear to run time to unlock the hand throw points.

Clear signal eastbound at VERMONT ST.
 Looking down at the operator's desk we can see the paper Station Record of Train Movements and over above the controls for INTERCHANGE interlocking are various CSX phone numbers for the dispatcher and operator that control the other BLUE ISLAND interlocking.

In this final shot inside the tower we look lengthwise along the N-X console from left to right showing most of what I mentioned before including more of the operator's desk. Power for the florescent desk lamp and fan come from an outlet suspended from the back wall via a wiring pipe. All told the N-X territory has 28 numbered signals and 13 switches. One major anomaly is the lack of explicit signal protection on the main track for the 69 switch at the end of the westbound Beverly Branch extension. This implies that the logical INTERCHANGE interlocking might be functionally part of the BLUE ISLAND plant and given the documentation in the employee timetable and the lack of a remote relay hut that is highly likely, however INTERCHANGE is designated a separate logical location on the Blue Island panel and I treated it as such. Another design quirk is the single track bottleneck for trains coming on and off the Beverly branch where both branch tracks merge into one over the 83 switch.

83 switch bottleneck.
 If the 83 switch were to be simply moved east of the 87 switch then full parallel movement would be enabled without any additional switches. A similar head scratcher was seen at Gresham Junction before it was reconfigured. Finally one notices the duplication between INTERCHANGE and ROBBINS that creates a pocket on the interchange track between the two switches over to the main line.As I mentioned before, this is used to let peak period Blue Island terminating trains to lay over east of the 87 crossover . There also appear to be two blocking devices fitted to the signal into the station stub and Beverly branch extension. I assume these would be for rusty rails and one clearly looks a bit more official than the other, but both serve the purpose of preventing the N-X buttons from being depressed.

That's all the coverage I have of METRA Blue Island. You can check out the rest of the photos for slightly different versions of the ones I posted here. While not as historic as A-2, UD or 16TH ST, the N-X panel is an interesting contrast to the Unit Lever panels we have seen in most of the other towers and sheds some light on a period of North American signaling that came and went quickly. For an in-depth discussion on the technicals behind a relay interlocking plant such as this check out this highly informative page on the Petone signalbox in New Zealand.

Stay tuned for a follow up post regarding the unique method of operation on the Beverly Sub.

UPDATE: You can check out a set of photos from a 2016 visit to the tower here.

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