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| Chicago's Tower 18 (Photos) (1070601) | |||
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Chicago's Tower 18 (Photos) |
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Posted by ChicagoPCCLCars on Mon May 30 23:13:23 2011 I've mentioned in my other topics how personnel on DART in Dallas were amazed at the complex junction on Chicago's CTA known as Tower 18. DART junctions are all flat junctions and are all automated. Several DART operators expressed surprise that Tower 18 is manned 24/7. Four routes operate through the junction seven days of the week and a fifth runs during the weekday am and pm rush. Here are the photos I shared with the folks in Dallas. The old Tower 18 from the north, onboard a SB Brown line train. The home signal is displaying yellow over red for the straight route. CTA signals give indications by relative position of apects and not by separate signal heads. This gives plenty of economy...the top red aspect and the same middle yellow would give the diverging indication. Both reds give the stop indication. Both reds and the bottom lunar would give the call on. The speed limit signs supercede cab signals. 10 MPH is the diverging limit but the cab signal would show 15 MPH (yellow sign).  The junction from the opposite direction, we're onboard a Pink line train. The home signal to the right has three routings. Orange line trains turn to the right. Outbound Pink line trains turn to the left. Purple line trains go straight. The Loop "L" is a two track railroad all around. The tracks are named "inner loop" and "outer loop". Inbound Brown line trains use the straight track at the left, and exit on the outer track at the right, turning right onto the track straight ahead. Purple line trains come in like a Brown line train but turn to the right here, in front of the camera, onto the inner track and go off to the right. Green line trains go straight across at right angles, in both directions. Inbound Pink line trains also go straight, from the left to the right, circling the Loop til they get to the camera position.  The junction from the east.....but I'm on the rear car of an Orange line train. A rare move that sometimes happens....the movable bascule bridge to the right might get stuck in the up position. Tower 18 would then route an outbound Brown line train across the junction for another trip around the Loop "L" to keep service going.  A closeup of frogs, guard rails, and our famous exposed third rail. David Harrison |
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