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Thursday, November 20, 2014

CTA Mini-Towers

The Chicago Transit Authority has remained a strong supporter of the "tower" system of rail transportation control.  Just like the NYC Subway and the Long Island Rail Road, the CTA's traffic density still gives an edge to human eyes and judgement in place of automated routing and remote control.  Those who ride the CTA are probably aware of the currently manned towers placed at the yards and major junctions.  It is pretty hard to miss them the way the operator's cabs typically cantilever out over the tracks.

The CTA even produced this video showing its recently rehabilitated towers at TOWER 18 and CLARK JCT, which received brand new NX Panels.

However the CTA has another type of tower, one  that is almost ubiquitous, but also hard to spot.  While local control panels are a common feature in most relay rooms, the CTA steps things up one notch by placing many of these, from junctions to simple crossovers, in their own little booths.

 The most "tower" like of these mini-towers is TOWER 12 at the southeast corner of the loop where Orange and Green line trains split off to the south.  While this junction is normally remote to Tower 18, there is still a small porta-potty sized booth where a human operator takes over at peak periods.

Another form of the CTA "mini-tower" is a space built right into the trackside relay huts.  Again the giveaway are the windows placed in a manner that would allow an operator full view of arriving trains.

Here is a portable interlocking cabin set up at the Harlem and Lake Green Line terminal and again the small window for manned operation is present (also note the interlocking horn).

Finally, sometimes the operator can get his own stand-alone booth on the station platform.  One such mini-tower is located at the south end of the Damien Blue Line platform.

This mini-tower controls a small scissors crossover immediately behind it.

The interlocking is clearly remote from somewhere else, but as you can see the Damien local tower has a fully functional panel.

 It has NX buttons for the signals as well as overrides to throw the switches without a signaled route.  It also has buttons for the direction of traffic on all four exits, call-on buttons and even a button to sound the interlocking horn.  Of course there are switches to set control local, remote or automatic.

What's interesting and a touch ironic is that at the opposite end of the same platform is a classic style tower that was built, but never placed in service as the junction it was to control was eliminated.  It looks like the CTA took a second bite at the apple. :-)

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