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  • Construction of Turnback track at Eastern Market

  • Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.
Discussion related to DC area passenger rail services from Northern Virginia to Baltimore, MD. Includes Light Rail and Baltimore Subway.

Moderators: mtuandrew, therock, Robert Paniagua

 #1279056  by DiscoveryAnalysis
 
I know that WMATA in their 2040 plan included a possible pocket track east of Eastern Market. However that would cause massive disruption to the entire segment between Eastern Market & Potomac Av. Instead construct a single Turnback track aprox 150' east of the D06 interlocking of TRK1 to run roughly 2000' under 9th ST SE. This would allow for a Gap train to be parked in the tail track while allowing an additional 8 pack to turn back. This could be constructed in conjunction with phase II of the SV line and upon opening utilize it to reverse SV line service and/or core trains (I'll post that later)
 #1279397  by Sand Box John
 
"DiscoveryAnalysis"

I know that WMATA in their 2040 plan included a possible pocket track east of Eastern Market. However that would cause massive disruption to the entire segment between Eastern Market & Potomac Av. Instead construct a single Turnback track aprox 150' east of the D06 interlocking of TRK1 to run roughly 2000' under 9th ST SE. This would allow for a Gap train to be parked in the tail track while allowing an additional 8 pack to turn back. This could be constructed in conjunction with phase II of the SV line and upon opening utilize it to reverse SV line service and/or core trains (I'll post that later)


Had to check my drawing of Eastern Market to be sure. Not possible as the east end of the D06 interlocking is under the west edge of the the intersection of 9th Street and Pennsylvania Avenue SE.

Excavation for the pocket track would likely be done using the New Austrian Tunneling Method. The removal of the sides of the existing tunnels would be done piecemeal after the new tunnel is structurally complete. As I recall the existing tunnels have floating slab track beds in them. Tying the track beds from the old tunnel to the new tunnel should pretty easy because of the floating slabs. The only thing that will require significant preparation is the installation of conduits to carry the cables that have to be moved before the side of the mainline tunnels are removed.

Now your idea of connecting a siding to the outside of the mainline still can be done as the mainline tracks are under the left lanes of Pennsylvania Avenue. It would make more sense to connect the siding to the westbound track to allow the gap train to enter the mainline westbound without fowling the eastbound mainline. The end of tangent at the west end of the curve west Potomac Avenue station is roughly 1,500' east of the D06 interlocking. To achieve your 2,000' length, the siding would duck under the mainline tunnels at the point where they curve into the Potomac Avenue station.
 #1279507  by DiscoveryAnalysis
 
Your suggestion of attaching the Turnback to TRK 2 is a little more plausible, and I'm not near a map but maybe a gentle curve toward the north to avoid diving under existing tracks.

For the record I'm against the construction of traditional pocket tracks within the existing system.
 #1279598  by Sand Box John
 
"DiscoveryAnalysis"
Your suggestion of attaching the Turnback to TRK 2 is a little more plausible, and I'm not near a map but maybe a gentle curve toward the north to avoid diving under existing tracks.


Not possible, as the tunnels that curve from Pennsylvania Avenue in to G Street pass under the front yards of the properties on the north side Pennsylvania Avenue and G Street at the intersection. If the tunnel ware shortened to avoid passing under the mainline they could only hold 14 cars, 1 8 car train and 1 6 car train. Ducking under the main line would kill two birds with one stone, it would allow the holding of 2 trains with room to spare and prevent trains from rolling out onto the mainline in the event of brake failure.

For the record I'm against the construction of traditional pocket tracks within the existing system.

Pocket tracks have the advantage of allowing trains to move off the mainline to hold and or revere direction without fouling the mainline.
 #1281778  by TheOneKEA
 
Sand Box John wrote:"DiscoveryAnalysis"
Your suggestion of attaching the Turnback to TRK 2 is a little more plausible, and I'm not near a map but maybe a gentle curve toward the north to avoid diving under existing tracks.


Not possible, as the tunnels that curve from Pennsylvania Avenue in to G Street pass under the front yards of the properties on the north side Pennsylvania Avenue and G Street at the intersection. If the tunnel ware shortened to avoid passing under the mainline they could only hold 14 cars, 1 8 car train and 1 6 car train. Ducking under the main line would kill two birds with one stone, it would allow the holding of 2 trains with room to spare and prevent trains from rolling out onto the mainline in the event of brake failure.

For the record I'm against the construction of traditional pocket tracks within the existing system.

Pocket tracks have the advantage of allowing trains to move off the mainline to hold and or revere direction without fouling the mainline.
Agreed. They are also useful for holding track work trains and for getting duds off the mainline tracks and out of the way until they can be serviced and returned to a yard.The only downside is that they can't be easily extended if needed, because many of them are double-ended.

I've argued in other threads for the construction of a pocket track in the vicinity of Eastern Market for the use of late-running Silver Line services, so I also hope that Metro constructs this facility.
 #1281820  by Sand Box John
 
"TheOneKEA"

Agreed. They are also useful for holding track work trains and for getting duds off the mainline tracks and out of the way until they can be serviced and returned to a yard.The only downside is that they can't be easily extended if needed, because many of them are double-ended.


They only need to be long enough to hold 1 8 car train, only one is longer then 8 cars (West Fall Church) and that is only because there is a curve beyond the east end of the platform. All of the pocket tracks are double ended.

Springfield - Franconia has a 3 track tail track that can be converted in to a double ended pocket track when an if the J route Blue line were extended south. Largo has an underground 3 track tail track as well, actually it's a light maintenance and storage facility, however if the G route Blue line were extended east it would not utilize tail tracks 1 and 2 for the mainline as there are separate provision for a junction to extend the route between the east end of the platform and the tunnel portals.