Blue Line Dulles Realignment

[mgandrejco]

I know the Blue Line realignment people usually talk about is the construction of a new tunnel through downtown DC in order to reduce congestion on the current Blue-Orange-Silver line tunnel; congestion that will only get worse once the Dulles extenstion is completed and more Silver Line trains will be put into service. However, one of the main reasons the WMATA is reluctant to move forward with the plan is the high cost of tunneling a new tunnel all the across DC from the Potomac to Maryland.

My idea would be to instead build a new westbound connection between the Blue Line and the Orange/Silver line. Instead of running through DC the Blue Line would travel from Arlington Cemetery to Courthouse and continue on to the Silver Line terminus at Ashburn. Now adding this connection on its own would not solve the problem of congestion on the shared line since there would still be 3 lines of the same track between Courthouse and East Falls Church. This is why I also believe that there should be a new tunnel built either parallel or under (whatever's cheaper/easier) the existing line to run Silver Line trains on. This tunnel would be an express tunnel with no stops at any of the 5 stations on the concurrency. Passengers who wish to go between those stations and the Silver Line can instead take Blue Line trains. Additionally, there would be an added benefit of quicker travel times from Dulles to downtown DC. As for the Maryland segment of the Blue Line, that would just become a solo segment of the Silver Line.

What made me think of this was the fact that I noticed the fastest way to get from Alexandria to FedEx Field was the take the Yellow line and transfer to Blue Line at L'Enfant Plaza rather just take the Blue Line from start to finish. I thought that was kinda stupid for the Blue Line to double back like that, but looking at the map it made more sense for the Blue Line to turn West and stay in VA rather than go East into DC. Furthermore there should be a demand for a 1 seat ride between the employment hubs around Tysons Corner, Pentagon, Crystal City, & Alexandria, in addition to connecting 2 out of 3 of Washington's airports. Furthermore, the construction of the Purple Line in MD speaks to the demand for greater transit options connecting the suburbs, and bypassing downtown.

[mtuandrew]

I live out in west Alexandria too (Van Dorn is my stop) and I loved Yellow Rush Plus because of how much longer the Blue Line takes. Adding Silver Line to the Potomac tunnel has negatively impacted congestion southwest of DC.

You have a creative solution, but not the most practical since it doubly inconveniences Virginia travelers to DC (there’s no direct DC service from Franconia-Springfield, Van Dorn, and Arlington Cemetery with your plan) and still doesn’t solve the Rosslyn bottleneck in Blue/Orange/Silver service today.

Long term, I would like to see two major projects on the Virginia side:

1) moving the Orange/Silver transfer to West Falls Church with separate Orange and Silver platforms, and

2) a much larger, longer-term project of fully rerouting the Silver Line. Specifically, I want the Silver rerouted down Route 7 (Broad Street/Leesburg Pike/King Street) all the way from the 66/267 interchange to I-395, northeast along the highway to South Glebe, then east to Reagan National Airport. Broadly, stations being:

• West Falls Church
• Downtown Falls Church
• Seven Corners
• Baileys Crossroads
• Skyline
• Shirlington
• Reagan-Washington National Airport

Then into DC via the Yellow Line bridge. It’s slower than the current Silver Line but potentially a better fit with the direct airline connection and Crystal City access.

It would be a $5 billion project of course, pushing $10b if you include Four Mile Run remediation, grade separation of Route 7, and installing an enormous traffic circle in Seven Corners.

[Sand Box John]

@ mgandrejco

Your schemas assume the suits conclusion that the C and D routes from Rosslyn east can not carry the needed capacity. Fact is WMATA has never had a large enough fleet to prove that theory to be an actual fact. I happen to believe that a fleet large enough would debunk that theory.

At present WMATA runs its railroad at around 55% of the train control and signaling system designed capacity. Increase the fleet size and run the trains on a clearly defined schedule with clearly defined station dwell times would easily allow more then 80% of the systems designed capacity to be used.

For your information the train control and signaling system designed capacity for the all routes on the railroad with the exception of the N Route segment of the Silver line is 40 trains per hour. The N Route segment of the Silver line is 26.66 trains per hour.

[mgandrejco]

I realized I forgot to add that the Blue and Yellow Lines would use both of the terminals at Springfield and Huntington. This way people using both segments will be able to get downtown or get to Tysons Corner/Dulles. From a technical point I don't think this should be an issue since both segments have only 2 stops and both share the rail yard at Eisenhower Ave. As for Arlington Cemetery, since nobody lives there(obviously), relatively few people work there, and most passengers that use that station are tourists so I don't think have a direct connection downtown is a big deal. Especially when you consider that the next stop in both directions is a transfer stop.

I also want to make clear that under my plan the Blue Line would no longer stop at Rosslyn. The next stop after Arlington Cemetery would be Courthouse. Therefore only 2 lines will be running through the rosslyn tunnel as it was originally designed to carry. As I also mentioned in my original post I also think that adding express tracks for the Silver Line between West Falls Church and Courthouse would prevent the bottleneck from being moved to that section.

@mtuandrew the main problems I have with your second suggestion is that route 7 doesn't go to Dulles; it actually seems to be a solid 5.66 miles away from the terminal at its closest point. It would also require entirely new construction of the entire line plus the abandonment of the brand new alignment the WMATA just spent $6.8 billion on. One of the main reasonings of my idea was to limit new construction as much as possible to minimize costs, and yours does not do that.

@Sand Box John I'm unsure whether your figures are in regards to the current manual control system currently employed by Metro or the Automatic Train Operation system that has been disabled since 2009. To the best I was able to find under the current manual system the rosslyn tunnel can only handle 26 trains per hour. I heard that ATO will be returning to service during rush hours sometime this year so we will have to see if that makes any significant improvements. However, I want to point out that some of the worst delays on that section have been caused by mechanical issues on the trains or on the tracks, and noticeable delays have been caused by platform crowding. These are issues that won't be resolved by improved utilization of signalling capacity, and it should be noted that a delay in this section delays half of all of the lines in the metro system. Having half the system running through a single 2-track tunnel is, in my opinion, asking for trouble. I think that by separating the Blue Line, Metro will be able to improve service reliability, increase passenger satisfaction, and thus boost ridership.

Also thanks both of you for the feedback. This was the first original thread I've posted on this site and I'm glad it garnered some interest.

[Sand Box John]

"mgandrejco"
and Box John I'm unsure whether your figures are in regards to the current manual control system currently employed by Metro or the Automatic Train Operation system that has been disabled since 2009. To the best I was able to find under the current manual system the rosslyn tunnel can only handle 26 trains per hour. I heard that ATO will be returning to service during rush hours sometime this year so we will have to see if that makes any significant improvements. However, I want to point out that some of the worst delays on that section have been caused by mechanical issues on the trains or on the tracks, and noticeable delays have been caused by platform crowding. These are issues that won't be resolved by improved utilization of signalling capacity, and it should be noted that a delay in this section delays half of all of the lines in the metro system. Having half the system running through a single 2-track tunnel is, in my opinion, asking for trouble. I think that by separating the Blue Line, Metro will be able to improve service reliability, increase passenger satisfaction, and thus boost ridership.

Back in the 1970s and 80s WMATA ran trains at 95 to 98 percent of the civil speed limit, today they are run at 65 to 75 percent of that same civil speed limit. Other thing limiting the number of trains per hour is the lowering of the performance profile of the rolling stock. The rolling stock has been detuned reducing their rate of acceleration. The automatic train supervision subsystem is not fully exploited to time the approach of trains to the merging junctions. Under WMATA's present manual operation procures station dwell times are ridiculously long limiting the number of trains per hour. Under automatic operation they are still to long, again limiting the number of trains per hour. The clocks that define dwell times are set to long creating a condition where trains are stopped at platforms with their doors open for a duration of their runs cutting into the number of trains per hour that the train control and signaling system can push down stream.

The more trains you run the shorter the duration of time passengers are waiting on the platforms resulting in less platform crowding and less time needed to discharge and board the trains. WMATA's daily ridership at any given time of day is generally pretty predictable and static. Trains running at closer headways will put more of that ridership in motion then waiting in crowds on platforms.

[orulz]

@mtuandrew the main problems I have with your second suggestion is that route 7 doesn't go to Dulles; it actually seems to be a solid 5.66 miles away from the terminal at its closest point. It would also require entirely new construction of the entire line plus the abandonment of the brand new alignment the WMATA just spent $6.8 billion on. One of the main reasonings of my idea was to limit new construction as much as possible to minimize costs, and yours does not do that.

This is not what he has proposed. He has proposed to de-interline the Silver and Orange lines. The Orange Line gets its own route from West Falls Church to Rosslyn (where it would then merge with the Blue); the Silver Line keeps the part of its route not shared with the Orange Line. Where the current Silver Line currently curves from the median of the Dulles Toll Road onto the median of I-66, it would be modified to instead go straight. Add a second upper level to the Orange Line's West Falls Church station, turn it into a '+' shaped transfer station between the Orange and Silver. The closest comparison within the existing Metro system is how the Green and Red cross each other at Fort Totten for a transfer that is outside of the core of the city. The line would then contine from there along Route 7, presumably underground until Seven Corners and then mostly elevated from there.

This would be a fantastic line for inner Fairfax and outer Arlington and would be pretty useful and probably popular, but on the other hand, it doesn't really solve the problem. The downside is that this would essentially result in another situation where three branches share the same trunk (In this case, Yellow/Blue/Silver between National Airport and Pentagon, and Yellow/Green/Silver north of L'Enfant. This would limit frequency on those branches compared with the present condition. So basically, it causes the same problem you're trying to fix, just in a different location.

The problem no mater how you slice it is: too many branches, not enough trunks. Even if you move more trains onto the Yellow Line bridge to take advantage of the spare capacity there, you still run into a bottleneck where it merges with the Green Line. Adding more trains onto the Yellow Line bridge isn't really that much help until you have a plan for where they will go after they cross into downtown.

Turning only part 1 of @mtuandrew's solution, turning some the silver line into a shuttle that requires a transfer at West Falls Church, actually does solve some of the problem, effectively pruning the branch. You could go ahead and connect it along Route 7 to National Airport and terminate it on the third track there. Other similar proposed solutions have been to put a separate platform for the Blue at Rosslyn and terminate it there.

But if you just reattach it to the existing trunks somewhere else in the system, the problem returns, just shifted around.

[Sand Box John]

"orulz"
Turning only part 1 of @mtuandrew's solution, turning some the silver line into a shuttle that requires a transfer at West Falls Church, actually does solve some of the problem, effectively pruning the branch.

When all is said and done I happen to believe a good percentage of the origin, destination trips on the Silver line will be between McLean and Ashburn justifying the running trains between those stations. The planers that prepared the Draft Environmental Impact Statement believe the same as there was a pocket track east of McLean for that service in that document. The bean counters deleted that pocket track along with pocket tracks west of Spring Hill and Dulles Airport in the name of cutting costs.

[mtuandrew]

orulz: exactly what I propose, and you’re right about it causing issues elsewhere. Perhaps like some of the YL service terminating at Mt Vernon Square, some of the SV trains on my mythical Route 7 Line would end at the Reagan National pocket track, with three full mains between there and the BL/YL and SV junction around 33rd Street (half a mile south.) That would fulfill my wish for an airport connector anyway, and an easy cross-platform connection to Crystal City and the Pentagon.

I wonder whether revenue tracks could be rearranged in such a way at West Falls Church to enable a part-time Ashburn-WFC shuttle, by S-curving through WFC yard tracks into the west end of the station. Tracks are already set up perfectly within WFC station to allow a center platform SV shuttle with through OR service, or vice versa, and a single track connection already exists from the SV line in the median of Highway 267 into WFC yard. You’d just need a second track, and to signal those tracks.

[Sand Box John]

"mtuandrew"
I wonder whether revenue tracks could be rearranged in such a way at West Falls Church to enable a part-time Ashburn-WFC shuttle, by S-curving through WFC yard tracks into the west end of the station. Tracks are already set up perfectly within WFC station to allow a center platform SV shuttle with through OR service, or vice versa, and a single track connection already exists from the SV line in the median of Highway 267 into WFC yard. You’d just need a second track, and to signal those tracks.

Could it be done? Yes. Would it be practical? Probably no. See track map, the West Falls Church station and yard lead junctions are in the middle of the graphic, Falls Church yard is the lower left corner of the graphic.

To get from N route mainline north of the Falls Church Yard lead track 3 junction to the Falls Church Yard lead track 2 junction, to pocket track K3 at the platform in the West Falls Church station would require traversing roughly 3/4 of a mile of track, passing through 1 #10, 1 #6 and 7 #8 turnouts at a restricted speed of 15 MPH. Of that 3/4 of a mile roughly 5/8 of that mile and 5 #8 turnouts under the direct control of the Falls Church Yard Tower. The other 1/8 of a mile 1 #10, 1 #6 and 2 #8 turnouts are under the control of the Rail Operation Control Center. The amount of time it would take to traverse that 3/4 of a mile from the N route yard lead junction and back from the West Falls Church platform would be mind numbing. it would also require close coordination between the yard tower and Rail Operation Control as the revenue train upon entering the yard limit is no long visible to the Rail Operation Control Center. The yard tower would also have to figure out, on the fly, when to fit in the random movements of rolling stock in the yard around the revenue train movements in and out of West Falls Church station.

It would be operationally faster to relay those train at the East Falls Church platform.