Search This Blog

Thursday, November 17, 2011


Last May Metra closed the last interlocking tower on its Electric Division running south out of Chicago. This was the former Illinois Central suburban routes electrified at 1500 vDC in the 1920's. Like many other high density suburban routes the Metra Electric continued to rely on on manned towers well into the CTC to deal with the traffic volume and complexity of operations. However over the last few years Metra has invested in closing the 3 towers on the line, Randolph Street (terminal office with some sort of relay machine), 67th St and Kensington.

Now I had always assumed that Kensington Tower would be the last to go because it was arguably more complex and also involved a crossing at grade of the CNIC freight main line by the South Shore Line, which diverged from the Metra Electric line there. Because of the three separate entities involved I figured a fight over funding and service quality would keep Kensington open. I was also under the impression that 67th St was some sort of more modern type relay based machine and Kensington was an ancient GRS pistol grip frame as that was how each was listed on the large Jon Roma list of towers. Turns out I had it completely backwards. Kensington had been converted to a relay plant controlled by a GRS TrafficMaster CTC console (and was originally a US&S plant), while 67th St had the GRS machine. Also I thought 67th St was some small office buried somewhere around the junction, while in reality it was a full on tower hiding in plain sight next to the tracks. I just never noticed it.

Anyway, I spotted this Blog piece on the closing of the last of the Metra Electric div towers and along with a good history of the tower (which you should read) there was a very tantalizing interior photo of the GRS Model 5 machine inside. I managed to track down the man who took the photos who was nice enough to send me his whole set on CD with permission to post them online and use them in my photo essays. The photos have been unmodified (apart from renaming) and left at their original resolutions to preserve the details inside the tower so you might want to click "View Image" to get the full amount of detail. The entire set may be viewed here.

Jumping right in, here is the best photo of 67th St that was provided showing a Metra Highliner EMU making a station stop in fairly typical Chicago weather. The tower is a large rectangular monolith with no typical "tower" accouterments, which is why I probably mistook it for a substation. What gives it away however is the massive arm bundles of signaling wires running out from the tower onto a local concrete pole line.  67th Street is located at the junction of the IC Main Line and the electrified South Chicago Branch which runs to a station only a short distance from the Quad Draws at CP-509.

 I should probably provide a little reference at this point. Here is a line guide to the Metra Electric division. There is an updated track chart at the bottom showing current CTC (red) and ABS (green) territories. both 67th St (MP 14) and Kensington (MP 19) interlockings used to be blue, indicating tower control. Express tracks are on the outside, local tracks on the inside serving island platforms. The tracks between 67th St and Kensington was upgraded to bi-directional operation some time ago, but between 67th St and Chicago it remains ABS. Moreover, between Roosevelt Rd and the Randolph St terminal, trains work on sight within unsignaled yard limits with hand operated points.

Back to the tower we head to the top floor where we find a surprisingly large 176-lever GRA Model 5 pistol grip style interlocking machine. While only a small fraction of the levers were in use at the time of its closure, back in the day the tower would have also had control of the 4 parallel freight tracks. Here we have the left side of the machine starting at lever 1.

And continuing to lever 176 on the right. 

As per standard practice red levers are signals, black the switches. Here is some detail of the 8x levers. Pulled out from the machine displays a signal or reverses a switch. The small button on the pistol grip is not interlocked, but instead is covered by any blocking device. The red buttons are for displaying a call-on signal.

View along the levers showing the glass top of the machine and a scented candle. One wonders how often that glass top needed to be repaired in the 80 years the tower operated. 

Here is a view of the machine straight on. From top to bottom we have the illuminated track diagram, then the row of signal rundown timers (supplied by US&S) with an emergency switch release box. then a glass fronted case switch and signal fuses and finally the levers. Is it just me or are the stickers on the fuse case sending some mixed messages? 

Here is the right side of the track diagram showing off the north end of the interlocking. This consisted of a 4-track double slip scissors crossover employing levers 132 to 176. As the route north of here is ABS the tower only has full occupancy lights on the southbound tracks. Below the diagram is a display showing which levers are currently locked out, next to some truly ancient portable radios.

The left side of the track diagram shows off the south end of the interlocking which consists of a duckunder junction for trains proceeding down the South Chicago branch. Main line local train must make a diverging movement at the split. Past the South Chicago split we see a double slip trailing ladder allowing express to local crossover. Also note the traffic flow indications for the bi-directional territory south of 67th St. 

Here we see the middle of the machine around lever 100. The flash of blue you see a the 4 remaining lock levers. Not to be confused with facing point locks, these levers set the direction of travel between the north and south sections of the interlocking. You can see their position on the center of the track diagram. Also worthy of note are the blocking devices which have been constructed from lengths of radiator hosing and the long row of signal timers. You can also see how the levers have been further labeled with track numbers to prevent clearing the wrong signal.

Above the lock levers we have the manipulation chart. The to/from is given in terms of signal lever numbers. 

A cover was removed from the front of the machine showing off the more mechanical components of the GRS machine. I am sure that mechanical signaling enthusiasts are more knowledgeable about this sort of thing than I am. One can clearly see that the GRS power frame technology was clearly rooted in its all mechanical predecessors. The US&S frames used a differently designed horizontal locking bed along with more electric locking elements.

Here is a surprisingly clean operator's desk with the Record of Train Movements (block sheet). 

 67th St also had remote control over two other interlockings. 51St St, on the left, was about about a mile to the south and 18th St was, well idk where that interlocking is. 51ST ST used a GRS NX panel with the little movable switch indications on the diagram. Here the 18 switch has been reversed and blocking devices applied, probably due to the express track being out of service north of that point. The portion of the interlocking on the former IC freight tracks has been taped over. The 18th St unit is of US&S design and might not be in service anymore.

Behind the CTC panels is the main DC power board for the interlocking. Those open knife switches are definitely not OSHA Compliant.

Wide view of the CTC and power boards with the 176 signal lever with blocking device applied. 

Traveling now to the basement we find an oil fired boiler that should probably require the presence of a CO detector.

Of course if that new fangled oil heating technology failed the operator had a fallback method of staying warm with this pile of coal! 

Moving up into the relay room we find old school glass relays with an awfully lot of new capacitors hooked in. Any signal engineers care to explain their purpose? 

Moving outside for a look at operations here we have a train arriving on the wrong track southbound at 67th St. You can see the double slip scissors crossover behind the train and the replacement signals (turned) above it. The old school signals use a Reading RR style oval "call on" head.

And here we have a South Chicago train disappearing into the hole. The signal must be fleeted as it has remained at Restricting instead of dropping to stop.

Well, that is pretty much it for 67th St...but WAIT, we have a little bonus! That's right we're going to take a trip to the long closed 51St tower, which is located about 2 miles north of 67th St and was closed and remoted to 67th St on the NX panel.

51ST St has the same general design as 67th, but is much shorter due to needing less space for a smaller GRS interlocking machine. 51St St was not visited during a blizzard so you can see some of the architectural details.

51ST St fund use as the relay room of the remote controlled interlocking. Here we see some of the larger relays used in the GRS NX interlocking logic.

Here is the other side of the rack used for the plugable relays. Look! The whole unit is shock isolated!! Perhaps an indication of cold war design?

Here is the termination panel as well as what looks to be new equipment. I do not know if 51St St was re-signaled along with 67th or if the old vital hardware just received a new front end to connect to the computerized dispatch office. I suspect the vital hardware stayed the same as the line remains ABS operation.

Closeup of the new local control panel.

Upstairs the old lever room is either being rehabilitated or is falling into disrepair. I can't tell. 

Wow, plaster and lathe. They sure don't make 'em like that any more. Wonder how warm that lever room would stay with the lathe insulation and drop sash single pane windows. Probably wouldn't win any certifications for energy efficiency XD

Well that marks the end of both my tour and 67th St tower. I am sure that the passengers and trainpersons will miss the high quality of service afforded by a local human operator. Stay tuned for more photo essays on Metra's still active interlocking towers.

No comments:

Post a Comment