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Monday, January 14, 2013

PHOTOS: METRA TOWER A-5 (Pacific Junction)

While I have now covered most of the major METRA operated interlocking towers in the Chicago Area in my ongoing web series there are still a few left in the bag and one of these is the partner in crime to the recently covered METRA Tower A-2 at Western Ave. Pacific Junction is a 4-legged junction on the old Milwaukee Road passenger network as it approached Chicago's Union Station. Logically it is composed of the Milwaukee Road main line to Milwaukee running North-South and the main line across Illinois splitting off to the west with a small freight spur heading west to the Chicago River industrial district. In practice the junction looks like a 90 degree crossing with connector tracks cutting each of the corners. Today the Chicago commuter railroad provider METRA owns both the interlocking plant itself and the tracks south to Chicago Union Station. All other lines feeding the interlocking are owned by Canadian Pacific which was previously handled through its SOO Line subsidiary. Today the line to Milwaukee comprises the CP C&M Subdivision while the line to the west is the Elgin Sub and together they host the METRA Milwaukee North and Milwaukee West commuter services.

On the ground Tower A-5 has a very interesting layout with a three track main line running north to west via a sweeping 90 degree curve and another two track main line splitting from the 3 track line to run north. The eastern two-track freight spur used to split from the western route of the 3-track line, crossing the north-south line via a diamond crossing, but the diamond has since been removed leaving access to the freight spur and wye track via the curved connections to the north-south line. Here in a photo from the Railroad Signal Collections site we see the A-5 interlocking plant from the west with the tower visible far in the background. While technically two of the three Elgin line tracks diverge into the C&M line, the weak route signaling used on the line offers each of the two rightmost tracks (tracks 2 and 3) a "Straight" route through the plant. In the photo the track #2 signal is displaying a lunar white Restricting indication due to another train running ahead in the same block. Previously the former Milwaukee Road lines utilized "bottom yellow" Restricting, which is derived from the older practice of having a subsidiary signal for "call-on" indications. This is why the track #3 signal has the gap between the lower and upper heads to differentiate R/Y Diverging Approach and R/*/Y Restricting. Use of Lunar White in place of bottom yellow removes this potential conflict. A 4th siding track also used to join the junction from the right, but this has been removed although its signal on the gantry has only been partly so.

Here we see the rear of the northbound home signal gantry for Tower A-5. A three headed signal is provided for each track as all three are provided with diverging routes. The right of way clearly had provision for 4 tracks, but as the model board no longer shows any indication of a 4th track I cannot comment on the original layout of the tower as I do not have an original diagram. Both home signal on the three-track route are provided with absolute exit signals controlled from tower A-5. The use of exit signals is an easy way to implement bi-directional operation with simple relay based interlockings as it simplifies a lot of the logic by not having to check traffic flow status when setting up a route through the plant.  Also note the 72L signal for track #2 which lacks a middle "diverging" head despite protecting the 63 switch which can send trains either north or west.  This indicates either that both routes are signaled for the same speed and thus do not need to be differentiated or that a diverging move would need to be made under a Restricting indication.

Here we see Tower A-5 as it sits in the exact middle of the junction just south of the diamond crossing single east-west track crossed the north-south line. I do not have as much information on Tower A-5 as I do some of the others so I can only guess at its age which appears to be from the 1940's or 1950's. Whatever it's exact age A-5 is an all relay plant and was not fitted with an electro-mechanical power frame as most of the other METRA towers were. The tower is of all brick and concrete construction with a flat roof. Still some expense was made at having some pleasant architectural details. Unlike Western Ave no attempt is made at having a bay window as this plant was 100% built and operated by the Milwaukee Road.

Here is a rear view of the tower from the employee parking lot. Entry to the operating level is via an external metal staircase and doors are also provided to the relay room and the basement which would contain the heating plant. The tower designation of A-5 is liberally applied to all 4 sides of the tower via paint instead of the more common sign method.

Here we see the view inside the tower standing just inside the doorway. The rear of the operator's console is to the right with the communications racks straight ahead. You can see the old telephone concentrator unit with modern racks of radio equipment next to it. To the left we see a vintage water fountain mounted outside the bathroom wall. The interior is composed of large tan brick tiles. A bit of Tower Window Syndrome is present with the original windows having been replaced or covered over and even the replacements having been fitted with supplementary plastic sheeting to keep out the cold or the sun.

Here we see the operator's desk and the interlocking control console looking back toward the rear door. The machine is a US&S unit lever CTC style machine with direct wire control over the local interlocking. The model board is mounted directly above the lever panel and has seen some modifications compared with a standard CTC machine designed for lower density lines. Sitting on the right operators desk is a station record of train movements also known as a "block sheet" in which all train movements through the interlocking plat are recorded. To the left is a spiral bound pad of track permits for either train movements or for track workers requiring a possession. The three permits visible on the left have all been marked as void after they were cancelled. Also visible on the far right is the new telephone concentrator.

Here we see a closeup of the console and model board. Switches and signals are numbered sequentially with switches being single turnouts or paired crossovers and signals set up in the normal US&S Left-Right system. White lamps are for track occupancy and in most cases are paired for redundancy (not a common North American practice). Green lamps indicate a displayed signal and those signals with both straight and diverging indications being provided with a second green lamp to confirm which route has been set. Red lamps probably have something to do with direction of traffic, but I am unsure of this. The interlocking is divided into 6 "locations", each of which has a "power off" lamp on the console to alert the operator to power failures to portions of the plant. There are no additional signals within the interlocking save for those on the northwest and southeast wye tracks which protect two segments of non-circuited track. The possible signal indications are marked on the model board using the stick style notation. The junction consists of 9 crossovers, 6 single junction turnouts, one movable point diamond, 9 high signals, 5 dwarf signals and 8 exit signals. If you look at the 32R and 34R signals at the northern signal gantry you will notice no provision for a diverging route despite the presence of crossovers. This implies that many routes over crossover switches can must be done over a Restricting indication. Aside from the 33 and 31 crossovers I am not sure which others would result in that result.

The current state of the model board and unit levers indicate that a train is approaching from the north on the C&M Sub as the train approaching light is illuminated, although the train has not yet entered the approach circuit. The 83 switch has been reversed and the 34R signal displayed for this train although the 72R exit signal for this route has not been displayed and is in fact blocked. Meanwhile the appears to be a train approaching from the west, but the 44R has not been displayed despite the 49 crossover being reverse. The 4L exit signal has been blocked so this track occupancy might be a possession. The 2R and 74R exit signals have been displayed, but are both set to be fleeted as reverse running on those lines is uncommon. The 67 switch is also reverse for a move onto the southeast wye track.

Here is a closeup of levers 2 through 56. Signal levers 2, 4 and 6 appear to have been added after the fact between 46 and 54 probably in response to a bidirectional signaling upgrade. Switch levers are on the top row with a green indicator lamp for normal (left), a yellow lamp for reverse (right) and a center red lamp to indicate the switch is locked out by a cleared route. No lamp lit indicates the switch is on center. Signal levers are on the row below with some being paired and others single. These levers are provided with a central red lamp for displaying Stop and yellow lamps for displaying a proceed indication. However these yellow lamps have been disconnected and substituted with green lamps on the model board itself. The exception are the 2, 4 and 6R signals which used the lever lamp to avoid modifying the model board panel and the 56 and 54 signals which were never important enough to get model board display lamps. Below the signal levers are the call-on buttons for displaying a signal into a route for which a track occupancy light is lit. All main non-exit signals are equipped with a call-on facility while the dwarf signals for moves front and to non-signaled track are not. Below that are the "fleet" switches which will re-display a controlled signal as if it were an automatic. All main and exit signals are equipped for fleeting.

A direct wire US&S machine such as this will act immediately upon movement of the lever toggle. A console that makes use of a CTC coding function will not code the command until a special "code" button is pressed. These would take the place of the fleet or call-on button. Some machines such as this would mix direct wire and CTC interlockings resulting in different behavior when a lever toggle was pressed. The blocking devices are clips that slide down over the lever to prevent movement right or left. In this case only signal blocks are applied that keep the lever in the central, non-displayed, position. Note the builder's plate at the lower left. Lighting for the console and desk are provided by florescent tubes between the panel and model board.

In this view over the operator's shoulder we see that the 'CTC' portion of the machine has been replaced by a video game console artfully worked into the old model board portion of the leftmost CTC cabinet. The unit levers have been removed and replaced by a computer mouse. Tower A-5 has CTC control of at least two remote interlockings. These include Tower A-4, the western end to the Western Ave Coach Yard (Tower A-3 handles the eastern end and is worked from a panel in Tower A-2) and the Greyland crossing where the C&M Sub crosses the former Chicago and Northwestern Cragin Line about 2 miles north of Pacific Junction. Both interlockings infrequently see conflicting movements and as a result the straight routes through them are fleeted. Also depicted on the VDU is the large Mayfaire crossing where the C&M Sub crosses the former Chicago Northwestern 3 track main line. This 3x2 diamond crossing is at least partly controlled from CY tower and the single track is just a simple way to represent when the crossing is lined for the CNW. Mayfaire interlocking does include two crossovers on the former Milwaukee line so there might be some kind of joint control where Tower A-5 gets a slot to set a route across the pant and then does so as it sees fit instead of calling CY to handle Milwaukee crossover movements. I am actually inclined towards the "no control" option as Grayland and A-4 each have "Local Control" and "Power Out" options while Mayfaire does not so it seems that interlocking is just for the A-5 operator's information. As you can see on the wall calender these photos are from May 2007.

Looking over the other shoulder we see another VDU'd CTC console, although this time it is out of service. Perhaps at one point that one handled Tower A-4 and the other one Greyland and eventually the two functions were combined into a single VDU. The door is open to let some fresh air into the tower on what looks to be a gorgeous spring day.

Operator on the bell phone in what is probably a posed shot. Note that between some of these photos someone had to use the bathroom. Also note the faux wood wall paneling where the original drop sash windows were made smaller.

Here we see a southbound Amtrak Hiawatha service train lead by F40PH cabbage car #90368 en route to Chicago from Milwaukee taken from just out in front of the tower. At the far right in the distance you can just make out the southbound signal gantry which is of a modern tubular aluminum type and probably went in with the bi-directional signaling. You can also make out the paired exit and entrance signals. ... ER_A-5.jpg

In our last photo of the day taken from the tower window we see METRA MP36PH-3S #413 headed northbound through the interlocking plant with a Milwaukee North service train in tow.

Well that was tower A-5, as always comments and questions are very welcome. If you are interested in seeing the remainder of the Tower A-5 photos they can all be found right here. I only have about two more towers and one of them is pretty short so I hope you are all enjoying the show.


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  2. Interesting configurations of the light towers as well as some valuable information. Were these put up by and designed by you? How long did it take for you to build these? Great post!