Stadium-Armory Pocket Track Use Questioned for Silver Line

"Breda3252"
What Metro management is terrified of (Dave K. alluded to it during the board meeting a something catastrophic) is a train holding short of the D&G performing a wheel climb as is crawls toward the switch, and possibility going over the side.

D. Kubicek is blowing smoke up peoples asses. There is an angle iron guard rail on all elevated to protect trains from falling off. If a train managed to climb over that guard rail it would also have to climb over the curb the safety railing is mounted on. WMATA's elevates are not like Chicago or New York elevates where there is nothing but tie ends on each side.

Then what's your best guess as to why they don't want to use the D&G pocket track?

There must be some reason (it might not be one we think to be a good reason, but there has to be a reason).

"JackRussell"

Then what's your best guess as to why they don't want to use the D&G pocket track?

There must be some reason (it might not be one we think to be a good reason, but there has to be a reason).

I think there are multiple reasons. Some have Merritt, some are nothing more then CYA and some are generated by fear.

Fear of derailment and the ripple effect such an indecent would have on that part of the railroad. Fear of being vilified in the media and by the NTSB as the result of derailment.

To my knowledge WMATA has never had a derailment in D&G junction.

Fear that operators will not be able to get their trains into the pocket track quick enough to maintain WMATA's so called maximum of 26 trains per hour. The pocket track is 2' longer then an 8 car train, controlling an 8 car train composed of cars of different series in manual mode is not as easy as controlling an 8 car where all the cars are of the series.

The interlocking is not configured to allow trains to be spotted in the pocket track automatically. Though it could be at little cost.

Pretty simple fix. Place station stop marker coils the appropriate distance from the center of the pocket track. Reconfigure the pocket track track circuit to mimic a platform track circuit. When a train transmits a D&G junction pocket track destination code, wayside set the pocket track route through the interlocking, both entry and exit. Train executes a programed station stop only if it's destination code is set enter the D&G junction pocket track. When the train come to a stop within the pocket track track circuit and transmits a train birthed signal to wayside, wayside changes the clear lunar signal at the exit end to red and releases interlocking to route the next through train. Exit to the west in automatic mode would require no modifications as the west exit would clear as defined by the schedule.

Sand Box John wrote:
The only thing that I can think of that might make it an issue is the number of train per day needed to be turned there might be greater then the numbers turned at Grosvenor and Mt. Vernon Square resulting in higher maintenance costs and time constraints from getting train in and out of the pocket track that might effect the total number of trains per hour WMATA want to process through the interlocking.

I got an different perspective on this issue the other day. A concern is the passing trains there are going far faster than alongside other pockets, placed near station stops. And there is a constant worry, based on proven experience [cough], of operators running red signals. So the fear is apparently of a high-speed sideswipe & resulting casualties.

"farecard"

I got an different perspective on this issue the other day. A concern is the passing trains there are going far faster than alongside other pockets, placed near station stops. And there is a constant worry, based on proven experience [cough], of operators running red signals. So the fear is apparently of a high-speed sideswipe & resulting casualties.

Allow me to blow that theory out of the water. As screwed as thing are, the likelihood of a high speed sideswipe is zero. One of the ATP systems that has not been disabled to keep train moving is the ATP systems that prevents trains from operating at speeds greater the 15 MPH when speed commands are displaying zeros. Speed commands reduce progressively as a train approaches an occupied track circuit. A train not fully clear of a pocket track interlocking would be occupying multiple track circuits elimination the possibility of the conditions that existed resulting in the Fort Totten crash of 06 22 2009.

"The EGE"
The pocket track is about 690 feet by my measurement.

"Mainland"
Per testimony presented to the Board, the D98 pocket track is 602 feet long. With an 8-car train clocking in at 600 feet, Metro has deemed the pocket track too short for regular use. Metro is also worried that extensive use of D98 will slow service across the line since trains would come from full speed out of Stadium Armory down to the speed needed to enter the pocket.

Audio of the testimony will be available shortly on WMATA's website for those interested.

I ripped this from page 140 of FQ12204_FINAL_DRAWINGS_120412.pdf (25.7 MB PDF file)


Whoever at WMATA that is claiming that the pocket track is 602' long is blowing smoke up everybodys ass.

272+97.49 is the point of the turnout at the west end of the pocket track.
272+97.38 is the west end of the pocket track track circuit.
273+05.71 is the location of the D98 34 signal at the west end of the pocket track.
279+40.70 is the location of the D98 44 signal at the east end of the pocket track.
279+49.17 is the east end of the pocket track track circuit.
279+66.96 is the point of the turnout at the east end of the pocket track.

634.99' is the distance between the signals at either end of the pocket track.
651.79' is the length of the pocket track track circuit.

The critical figure is 651.79', that makes the pocket track a touch over 2/3 length of a car longer then the length of an 8 car train.