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Wednesday, August 10, 2011


During a trip to Chicago back in 2009 I posted a number of photos in the area of METRA's KENSINGTON interlocking in a non-signaling related essay. Today I will take a more in-depth look at the tower and signaling equipment and will make use of photos from that and a previous trip along with interior photos taken by another another tower enthusiast.

METRA KENSINGTON tower is located on the Electric Division on Chicago's South side at 115th St. It was built by the Illinois Central Railroad as part of their electric line improvements in the 1920's. Unlike some of the other towers I profile I don't have as much exact historical information on this tower except, so I'll muddle through with what I do know and if anyone has corrections they can let me know. Up through the early part of the 21st century the Metra Electric division was still primarily a tower controlled line with control locations at Randolph Street Station (some sort of panel), Weldon Yard (non-interlocked with switch-tenders on all main tracks), 67th St (GRS model 5 electro-mechanical) and Kensington (CTC and direct wire panel). Metra first moved control of Randolph St into its central control room, followed by Kensington and its territory and finally in March 2009, 67th Street was cut over. The non-interlocked portion between Van Buren and Roosevelt is still controlled by switchtenders and of those three closed towers, only 67th St was technically re-signaled as its interlocking was electro-mechanical, not relay like the others.

Between Roosevelt and 115th St the electric line has 4 tracks and sits adjacent to the CNIC freight main line where 67th St handled operations at the flying junction with the South Chicago Branch of the electric division and Kensington handled the junction with the Blue Island Branch and the begining/end of the 4-track local/express operation as well as the leads into the Kensington yard and maintenance facility.  When METRA took over the commuter operations on the electric line the integration with the IC freight line was removed, with the notable exception of Kensington. This was because the Chicago, South Shore and South Bend interurban line to South Bend joins the IC line into downtown Chicago. The CSS&SB crosses the 4 tracks of the former IC freight main line on 4 diamonds, but also has switch connections with the freight line. METRA was not at all interested in having to beg the freight railroads for lineups for the South Shore trains so it retained operation of the interlocking.

As a quick note since the original CSS&SB went bankrupt the passenger service has been operated by the Northern Indiana Commuter Transportation District or NICTD (pronounced Nicht-Dee) and I will be referring to it as such.

The photos I will be presenting come from two sources. The first are my own taken on a trip in Summer 2009 from the Metra station platform within the limits of KENSINGTON interlocking along with a smaller number of photos taken during a trip in 2002. The second are from a railroad insider and are being posted with permission. These photos are being left in their original resolution so please do not hesitate to right click and view those images in their unreduced state.

As you can see on the right there are 4 Electric Line tracks and 4 CNIC tracks coming in from the north. The 4 electric line tracks squash to 2 for the single island platform. Then south of the platform the NICTD line crosses the CNIC on 4 diamonds and we see the ladders to reach the Blue Island branch and the KDY yard lead. There remains a single switched connection from CNIC to Metra, probably for freight moves to reach either the yard or the Blue Island branch. NOTE there is a complete set of crossovers on the CNIC and there is a considerable distance between the Kensington interlocking proper and the Blue Island Branch / Yard junction. It will be worthwhile to keep this photo handy to refer to as I show various points and signals.

We begin with the tower itself which is mostly of brick construction with a tile roof, typical for a power-frame tower built in the first half of the 20th century. Here we see a view of the north side with a pair of C&S employees walking the track.

Here is a slightly wider view. While the tower may have been closed it was not re-signaled as the relay hut in front still houses some or all of the vital components and those thick bundles of wires on the pole line still work the field equipment. The tower was re-signaled sometime earlier in its life with the power frame being replaced by a direct-wire panel which I will show later. As METRA was interested with operations, not replacing life-expired equipment they saw no need to re-interlock the complex plant, but instead remote controlled it from a downtown office building.

While the tower retains its bay window, something must have happened at some point in its life to require the entire facade to be replaced with plywood and two small replacement windows. This counts as an example of "tower window syndrome" and was probably Metra's solution to fixing a problem with the original floor to ceiling windows. Fortunately the other windows don't see quite as affected.

Fortunately the other windows don't see quite as affected. Also note that there is no external difference between 2002 when the tower was open and 2009 when it was closed.

In addition to CNIC freight trains, the 4 non-electric tracks host a total of 6 Amtrak trains per day. Here P42 #127 leads the morning Saluki northbound toward Chicago. You can see some of the complete set of crossovers on the CNIC tracks which would require the CNIC dispatcher to contact Metra operators to request special movements to be made.

Here we see a NICTD train doing its thing by crossing all four CNIC tracks via the diamonds. 

All points in the plant are electric GRS model 5's without dual control. Here we see the 19A switch on the southbound electric track just south of the station platform.

It is put reverse for NICTD moves onto NICTD territory.

The point machines are probably original and here we see those maintainers working on the 17A switch.

Some components have been replaced as seen here on the 11B switch.

Movements over the diamonds result in a Slow Clear indication on the 10R signal. Technically I believe this is a Diverging Clear signal as the IC used weak route signaling, but the lower head placement informs the driver of a slow speed route. Note one of the 4-aspect target type signals which are unique to this interlocking.

The 12R signal has a similar setup. All tracks are now bi-directional so there are no "wrong direction" dwarf signals present with the exception of one of the CNIC tracks to the south and the wrong direction NICTD track.

Years of frugal re-signaling at Kensington resulted in a real mish-mosh of old and new hardware. Here we see the rear of the 8L signal with three target type heads with the top being an original 1920's US&S design, the middle being a modern Safetran modular clamshell design and the bottom being an defunct 80's US&S modular design. This shows what is possible if a railroad choses not to waste its capitol improvement funds on unnecessary hardware.

The rear of the 10R signal reveals two 20's US&S heads with a modern 4-lamp Safetran head.

This photo was taken of the northbound signal gantry at Kensington covering a total of 7 tracks. From left to right we have three Metra tracks, the first with an all original signal with 2 three lamp US&S heads and a "pill" type 2-lamp Restricting (aka subsidiary) head. Next as a replacement for a wrong direction dwarf signal is a 3-head traffic light type signal. Then we have another semi-original signal with 2 US&S heads and a modern 4-lamp target that was probably designed to allow for a "Slow Clear" type indication. Again this is the only interlocking where I have ever see 4-lamp target type signals. Moving on we have another modern 3-target type signal replacement for a dwarf with 2 Safetran and one US&S manufacture and on the last two CNIC tracks we have the original 1920's signals. The unsignaled track has a dwarf further on. The signal on the first CNIC track was probably an upgrade to allow Amtrak tracks stopping at the Homewood station to use that track bi-directionally. Just from this one photo you can see how much of a chimera Kensington interlocking was and still is.

Also note that all of the CNIC tracks are equipped with exit signals (which may also be signals for a back-to-back interlocking). These are absolute signals that are controlled by the CNIC dispatcher so that CNIC crews and MoW workers never have to contact Kensington tower to get protection or permission as Kensington cannot clear a train into a CNIC block on its own. As far as CNIC is concerned, Kensington is an island of local control in a sea of CTC.

Moving down the 115th St platform a little bit you can see the aspect on the 12R signal more clearly along with the positions of the CNIC and Metra tracks in the area. Just FYI the overhead electrification is at 1500V DC.

Looking at the north end of the interlocking we see the 2L and 4L signals, which combined with the 10R and 12R make the station tracks fully interlocked pockets. Each of the signals have one of the 4-lamp targets, but only the 4L appears to need it for a "slow" speed route.

Zooming past the signals we see some trackwork that appears to be a little more complicated than it needs to be, possibly hinting at an earlier configuration of the platform and tracks. The express tracks are on the outside and the local tracks are on the inside to allow the use of a single island platform at local stops. Here we see the 9 switch as it changes into a semi-pocket track.

Zooming in a bit more we can see the southbound home signals and the northbound exit signals. Unlike on the southbound CNIC these exit signals are automatic and provide for some additional capacity. The two "elephant ear" type signals on the left are original to the original single direction ABS setup of the line. The two signals on the right, one target, the other traffic, were installed when the main line was made bi-directional on all 4 tracks after 2000. Likewise the wrong direction 4R signals were upgraded to high traffic light types from dwarfs at that time. You can still see the concrete mountings for the old dwarf signals. Also note on the 2R signals are original and the "pill" type target on the upper head of the local track which did not need a full Clear aspect due to the mandatory diverging route.

Again kudos to Metra for not simply discarding all the old hardware to use up all the capitol improvement money. Unfortunately they did not apply this principal when re-signaling 67th Street. I believe today it might be cheaper to install new parallel signals than cut over existing signals to new interlocking hardware.

Looking over at the CNIC side we see the same sort of mashups on the other Kensington home signals. However there are also exit signals for both the main CNIC tracks for the reasons mentioned before. The two tracks farthest from the Electric line are not signaled beyond this point and hence have an "End Block" sign.

Here we have the 4L signal displaying a Diverging Clear for a route onto the express track. The CNIC exit signal is at Approach after the Amtrak train passed it. 

Soon after the exit signal went to Clear as the Amtrak proceeded toward Chicago.

Finally a south shore train knocks down the 4L and diverges onto the express track.

The 20R signal governing one of the un-signaled tracks is composed of two eras of modular target signals. US&S round modulars are themselves rare in this configuration, but as I said that 4-lamp safetrain is probably unique to this project. They were probably installed to replace a lower speed signal that was provided in lieu of Slow Clear.

The 16R was also a modern dwarf signal replacement.

While both the 18R and 14R use the original hardware with new lower heads replacing the old "pill" type 2-lamp heads. Note the 14R is tucked in behind the 4L.

 There was a power supply in the middle of the interlocking that appeared to be feeding some or all of the interlocking plant.

You can also see how the old timey interlocking pole lines are still in use and well maintained.

Alright, now it is time to see how things work behind the scenes.

Are first step will be appropriately behind the tower showing the entrance into the C&S workshop...

...that lists the address as still part of the ICRR.

On the north side of the tower are the regular stairs mounted in the British style.

And on the south side we see an emergency ladder, which is a feature common to Chicago area towers. I guess they are still paranoid about that whole great fire mess.

Out in front the operator is showing us that the windows do still work.

Hmmm, looking out for hotboxes or posing for the photographer?

Once inside we see the operator at work at her nice clean desk. I had always believed that Kensington still contained some sort of GRS pistol grip machine so I was surprised when in this photograph I saw not one but TWO panels.

Now in the far corner we see what is clearly the older panel. I showed this before, but that was because I needed a track diagram. Here I'll discuss how it works. The panel appears to be GRS, but might be some generic brand. It uses the US&S style R and L lever designations, but GRS was known to make panels with this sort of labeling so that would not disqualify it. I don't know if the old panel was still in operation as none of the lamps appear to be lit, but this could be an artifact of the photo. I covered most of the plant in my outdoor tour of the interlocking, but note the diamond uses a large trap circuit that has emergency releases provided (I heard something about trap circuits being easily stuck occupied somehow, perhaps someone could enlighten me).

Note there are a number of holdout signals on the Blue Island branch (32 and 34). They might have something to do with the block working, but I don't have any details. The large red buttons are either blocking devices or call-ons. 

Now next to the old panel is what appears to be a newer panel branded a "GRS Traffic Master".  The Traffic Master was a brand of GRS CTC interface that was available in the 1980s and represented the last generation of "panel" type interlocking/CTC control before Video Display Units took over completely.  The Traffic Master differed from previous models of Unit Lever and NX panels by offering a compact user interface consisting of a small keyboard on which the operator would input short commands using dedicated function keys and numeric codes.  I don't know the exact details of operation, but it would resemble the operator first selecting a function like clear a route, then code the route they wish set.  These machines mostly appeared in local dispatch and yard offices before they were in turn closed and centralized into video workstation desks.  A few were and still are used on the New York City Subway and it is probably that they saw use on other transit systems as well.

The presence of this CTC panel in Kensington tips us off to the purpose of the older style unit level panel as being a backup manual control interface if the traffic master were to go down.  Furthermore we have an answer as to why this interlocking was not fully re-signaled as 67th St was when the local control from Kensington tower was eliminated.  It would have been simple to adapt the local interlocking control interface that taked to the panel type CTC machine to talk to new computers at the METRA dispatch offices downtown.

More evidence showing the new panel being less than contemporary is the tape over the 27th Sw connection between Metra and the CNIC indicating it has been removed. We also see lots of label maker labels and the south section of Kensington being re-named South Kensington interlocking, despite keeping the same switch and lever numbers. The CNIC portion is diagrammed separately below the Metra portion. I am unsure if Kensington ever had CTC control of the remainder of the electric main line, but from the Traffic Master that appeared to be the plan. From what I recall back when the tower was open CTC control to Forest Park was from Metra's office downtown.

Well the Traffic Master is clearly busy today as all the track circuits are lit up. That small keypad under the lamp is the way the operator lines routes.

A view of the desk and both panels without the operator. Note the plastic bag over the window AC unit to keep out the cold.

Another shot of the Traffic Master doing something, but I still don't know anything beyond the basic details of its operation.

Here is the DC feeder diagram for the overhead catenary electrification. What is perhaps more interesting is the vintage layout of the interlocking which included a double track set of diamonds for the South Shore line. BTW, note how the operators have collected a veritable Hall of Shame of Metra related newspaper clippings. Vote for your favourite! Mine is "Meta Workers' Fistfight Results in a Stabbing" XD 

Here we have the wide angle shot of the whole tower. The operator faces the tracks, but the huge Traffic Master console blocks any possible view. Operator lockers are at the back and most of the office equipment dates from the Cold War.

Here we see the operator working with her phone, block sheet, misc papers and mystery keypad.

I'll finish with an example of some of the traffic that passed by the tower. We begin with an NS freight train heading north probably on a transfer run from Markham Yard to a connection with its home trackage at 95th St.

A train of Metra Highliner MU's departing southbound from the station.

And finally a NICTD south shore train on the diamonds heading eastbound.

Hope you enjoyed all of that. You can see all of the interior photos at:

And the rest of the outside photos at:

If you happen to have any additional information that fills in some of the gaps in my knowledge that would be much appreciated. Also stay tuned for future updates as I learn more myself.

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