Metro FAQ: How will Silver, Orange, Blue fit at Rosslyn?

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Metro FAQ: How will Silver, Orange, Blue fit at Rosslyn?

by Matt Johnson • June 30, 2010 11:29 am

Rosslyn is a major bottleneck in the Metro system. Because the Orange and Blue Lines intersect at Rosslyn, the station can be a source of backups, especially if there are any problems.

Photo by dbking on Flickr.

Metro's switches can handle a train every 135 seconds—26 trains per hour—and that is the current throughput at Rosslyn. Ridership has been growing on the Orange Line, and some have called for WMATA to make room for more Orange trains.

Currently, the 26 spaces are allotted unevenly. The Blue Line has 10 slots while the busier Orange Line has 16 slots per hour. The Orange Line also has some 8-car trains, which give it a little more capacity. The Blue Line only operates 6-car trains.

Because of ongoing power upgrades and a lack of railcars, it is not currently possible to make all Orange Line trains 8 cars long. It might be possible to slightly increase the current number of 8-car trains, at best.

That means the only viable way to add capacity to the Orange Line is by adding trains at the expense of the Blue Line. And two years ago, Metro started thinking about doing just that.

Current (left) and proposed service (right).
Shows a given 12 minute period, but does not show the full TPH count.

The "Blue Line Realignment"—sometimes called the "Brown Line"—would redirect just under half of peak period Blue Line trains to run from Franconia to Greenbelt, crossing the Potomac on the Yellow Line bridge. Metro says they will probably sign the trains as Yellow since they run almost entirely on the Yellow Line route).

This proposal would allow for the addition of 4 more Orange Line trains per hour, which would help to ease overcrowding there. It would also add 4 trains per hour to the 7th Street/Mid-City subway between L'Enfant Plaza and Greenbelt. However, it would reduce the number of Blue Line trains headed for north Arlington and the Farragut Square/Metro Center side of downtown.

The Blue Line's Franconia end would see the same number of trains as it does now, but some of those trains would head for Gallery Place instead of Farragut West. At Largo, existing headways would be maintained by rerouting the "new" Orange Line trains to Largo. The only station which would see reduced service is the little-used station at Arlington Cemetery.

Potential new Metro map showing rerouted trains as Yellow.

This change will affect riders on the southern end of the Blue Line. The diagram below shows how travel times could be affected. Trips toward the Farragut West area would take no more than 6 minutes longer—the additional wait time for a Blue train—but it is possible that the trains that remain on the current route would become much more crowded. Of course, passengers traveling to L'Enfant Plaza would save 9 minutes over the current one-seat ride (via Farragut), and 5 minutes over the transfer-to-Yellow (at Pentagon) ride.

Based on an analysis I conducted a few months ago, we can see an estimate of AM Peak volumes on the rail system. A look at those figures gives us an idea about the breakdown of passengers on the inbound Blue and Orange Lines. If we look at the two segments of track approaching Rosslyn on the Blue and Orange Lines, we can see that about 35% of the riders passing through Rosslyn are coming from the Blue Line, while the remaining 65% are on the Orange Line.

Since about 38% of trains (10 out of 26) are on the Blue Line and 62% are on the Orange Line, loads are probably pretty well balanced. The fact that around a quarter of Orange Line rush hour trains are 8-cars long means that the balance is even more appropriate.

This is probably one reason that Metro has not moved forward with its Blue/Yellow reshuffling proposal. However, once the Silver Line opens, Metro will not have much choice in the matter. In order to get enough Silver and Orange trains through Rosslyn, some Blue Line trains will certainly be rerouted via the Yellow Line bridge. A likely scenario for trains per hour at Rosslyn would be 10 Orange, 10 Silver, and 6 Blue.

On the other hand, It will take time for Silver Line ridership to build, so WMATA may delay any major restructuring until new ridership patterns have established themselves.

44 comments

Tags: Rush Plus, Silver Line, WMATA

Why the Blue Line needs to keep calling at Rosslyn (Jul 1, 2010)
Proposed "Blue Line split": why blue? (Mar 12, 2008)
Communication is everything on "Blue Line Realignment," a.k.a. the "Yellow and Orange Line Service Increase" (Jul 12, 2010)
A cheaper route to Metro core capacity, part 3: More complex service patterns (Jul 1, 2009)
Metro work to close Orange, Blue lines this weekend (Nov 3, 2010)

Matt Johnson has lived in the Washington region since mid-2007. He has a Master's degree in Community Planning from the University of Maryland and a BS in Public Policy from Georgia Tech. He has worked in the planning field since 2006 and lives in Greenbelt, where he serves on the city's Advisory Planning Board.

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I don't have permission to view larger versions of any of these maps.

by NikolasM on Jun 30, 2010 11:36 am • link • report

@NikolasM:
Sorry about that. It has been fixed. Private is my default setting on Flickr when uploading, and I neglected to make the images public.

by Matt Johnson on Jun 30, 2010 11:41 am • link • report

For the Silver Line, can east-bound trains go from Court House to Arlington Cemetery? And could it then skip the Pentagon and head north up the Yellow Line to L'Enfant Plaza? Or, instead of going to L'Enfant, could it head south on the Green Line and continue to Waterfront and on to Branch Ave?

by M.V. Jantzen on Jun 30, 2010 11:44 am • link • report

Definitely makes more sense to refer to this as "Extending the yellow line to Franconia-Springfield"

This plan would also likely be a nice perk to the Yellow Line riders in Arlington County, as it would give them more frequent service into downtown DC, and allow for a single-seat ride to Greenbelt.

Also, I think there's still a great deal of uncertainty regarding the number of current orange line riders that will switch to Silver when it opens.

by andrew on Jun 30, 2010 11:45 am • link • report

What if WMATA installed faster switches at Rosslyn?

by Eric F. on Jun 30, 2010 11:47 am • link • report

@M.V.

No, the current track configuration does not allow trains to make those movements.

by Alex B. on Jun 30, 2010 11:47 am • link • report

@M.V. Jantzen:
At present, there is no track connection to facilitate the movement. Trains from Court House cannot turn toward Arlington Cemetery.

Nor can trains coming from Arlington Cemetery turn toward L'Enfant Plaza. And trains crossing the Potomac cannot turn toward Waterfront.

These three connections could increase redundancy in the system and are probably desirable from that perspective alone, but they will be expensive to build.

by Matt Johnson on Jun 30, 2010 11:48 am • link • report

What's the problem with taking capacity from the Orange line for the Silver line? Most of the Orange "crush" riders get off between Court House and West Falls Church anyways. Any Silver Line route would largely duplicate the same Orange line route. Most of the West Falls Church riders come from some point that will be covered by the Silver Line (either Reston East or Herndon Monroe). Also because the Silver Line trains will be 7000 series trains which are four car "couples" I think that route is virtually guaranteed to be all eight car trains.

by Joshua Davis on Jun 30, 2010 11:51 am • link • report

Do you know what the volume of riders is that change from Orange to Blue (or Blue to Orange) at Rosslyn? Could the Arlington Cemetery stop be replaced by shuttle bus service from Pentagon and Rosslyn?

It seems to me, that while it might be inconvenient for some, rerouting the Blue line across the Yellow line bridge and continuing it to Largo might make sense (as opposed to going through Arlington Cemetary and through NW). And Silver could continue with Orange until Metro Center or L'Enfant or something.

by Amin on Jun 30, 2010 11:55 am • link • report

@Joshua Davis:
I agree with most of your comment. However, don't expect that all of the 7000-series cars will operate on the Silver Line. Since they can only operate in 4 or 8-car sets, I think it highly likely that they won't appear on the Silver Line until ridership rises. (Unless Metro decides to operate 4-packs in the interim).

The 7000-series will probably all start out on the Green Line (since they'll operate out of Greenbelt Yard) and since the Yellow Line doesn't use 8-car trains.

by Matt Johnson on Jun 30, 2010 11:55 am • link • report

I'm glad Metro is seriously looking at this type of alternative, despite what I'm sure will be a vocal backlash by a lot of Blue Line riders.

Also, just based on casual observation as I have ridden through Rossyln consistently over the past decade or so, Blue Line trains are generally less crowded than Orange Line trains during rush hours.

by Lou on Jun 30, 2010 11:56 am • link • report

However you slice it, the silver line is quite likely to add more than 4 additional trainloads worth of people per hour. It's not going to be fun.

Arlington needs to add office space and put a brake on additional housing, it seems to me.

by Josh S on Jun 30, 2010 11:57 am • link • report

It seems to me that upgrading the power supply to handle more 8-car trains is pretty logical. To someone relatively unfamiliar with costs, it seems like the cost of doing that is less than the cost of building new tunnels to handle more trains. And if the current tunnels can only handle so many trains, that's the only way to expand capacity.

Am I wrong? How hard is it to upgrade the power?

by Tim on Jun 30, 2010 12:07 pm • link • report

@Tim

Metro is upgrading the power supplies, substations, etc. The cost is indeed well below that of new tunnels, but the added capacity doesn't solve Metro's long term capacity issues, either.

It's not hard to upgrade the power supply, but it takes time and money. And, as Matt mentions, you still need more rail cars to form all those 8-car trains. When you combine the time needed for the power upgrades as well as the lead time needed for car procurement, you're talking about improvements that are a couple years away.

by Alex B. on Jun 30, 2010 12:12 pm • link • report

@Amin, if you are talking about completely cutting off Blue Line service to Rosslyn, just remember that isolates National Airport, not to mention all the people who travel down to the Pentagon and Crystal City, plus all the future developments around Potomac Yard.

by Lou on Jun 30, 2010 12:13 pm • link • report

To echo Lou, it's not as simple as just closing Arlington Cemetary station and letting the tourists fend for themselves. It's the connection between Rosslyn and Pentagon that's important, for people who travel from the Rosslyn-Ballston corridor to jobs at the Pentagon and CC and for people who travel from old town and southern Fairfax to jobs along the RB corridor.

by JS on Jun 30, 2010 12:30 pm • link • report

As an Arlington Ridge resident (the 'hood south of Pentagon and Crystal City), I am not a huge fan of this. It will make getting into the city via Metro much less desirable for those of us who work in the Georgetown/West End/Foggy Bottom neighborhoods as well as the Golden Triangle/K Street portions of downtown that are west of the White House. There are some major employers in these areas (two major universities, multiple major international finance institutions, and tens of dozens of law firms and nonprofits) that undoubtedly employ workers and students who live in south Arlington, Alexandria, and points beyond to the south and southwest.

I'm already relying on a bus and train mix to get to work. Adding extra time to the train schedule (especially the additional headway for shoulder/off-peak service when I get out of work at 7 PM or later) guarantees that driving will be my choice for future transit. Once Ohio Drive reopens, it's an easy 15 minute drive into the office for me, even during rush. No way that I'll choose a 45-minute minimum commute, assuming minimal wait times.

by Dave on Jun 30, 2010 12:30 pm • link • report

Another joy of the silver line.

In order to take a 45 minute + (and probably $5) ride out to Dulles -- which is going to hard to do during rush hour and with luggage -- Orange line riders in Arlington are going to have a harder time catching the blue line to National. How does that make sense?

captcha: Demonic purpose

by charlie on Jun 30, 2010 12:37 pm • link • report

Converting all Blue Line trains heading along the current route (i.e. to Rosslyn) to 8-car trains would reduce the impact of having only half as many trains. Right now, you have 10 6-car Blue Line trains per hour coming into Rosslyn, for a total of 60 cars. Chopping this in half would leave you at only 30 cars per hour. Converting all 5 of the Blue Line trains heading through Rosslyn into 8-cars would bump the total up to 40 cars per hour. A 33% decrease seems to me to be much more manageable (and palatable) than a 50% decrease.

The problem, I'm guessing, is that the Blue Line track south of Rosslyn is not capable of powering 8-car trains, since neither the Blue nor the Yellow use them. Matt, do you know if this is the case and, if so, if this is on the list of power upgrades being undertaken?

To avoid confusion, it seems to me that it would be simpler to just send half the Silver Line trains on to Largo, while the other half turn around at Stadium-Armory, rather than creating a situation where the Orange Line has two different spurs (New Carrollton/Largo).

by Dizzy on Jun 30, 2010 12:39 pm • link • report

Re: M.V. Jantzen

The idea of sending silver line trains from Court House to Arlington Cemetary and then to L'Enfant, while not feasible now, might be a reasonable option in the future (if Yellow/Green line subway can handle the demand of Yellow, Green, and Silver service). I would assume it would be less costly for Metro to create the connections for this than to create an entirely new subway line that branches off from Rosslyn and proceeds through DC via Georgetown/Thomas Circle/Union Station (as has been talked about in the past). Having said that, if the money could become available, a new subway sounds more enticing. ;)

by Aaron on Jun 30, 2010 12:44 pm • link • report

"These three connections could increase redundancy in the system and are probably desirable from that perspective alone, but they will be expensive to build."

The Silver Line is also expensive to build. Adding additional capacity should come out of the capital budget for the project.

by Adam L on Jun 30, 2010 12:50 pm • link • report

How practical would it be to have the inbound orange and blue line trains stop at Rosslyn, at which point there would be a transfer to a third line that served DC and all points east?

I understand that it would basically be punting the bottleneck further down the system, but I think that if you can eliminate the switching delays, you could possibly run things a little more efficiently.

by MrS on Jun 30, 2010 12:51 pm • link • report

One other thought. Would it be possible to create the needed connections in order to have the blue line exclusively serve Virginia (similar to one of the lines in the Bay Area that exclusively services the East Bay without actually going through San Francisco)? So basically have the blue line run from Franconia-Springfield to Vienna/Fairfax-GMU (or East Falls Church to King Street)? Meanwhile, the orange line continues serving the same areas and the silver line takes over service that the blue line currently provides from Rosslyn to Largo Town Center? Metro would likely need to do a Yellow line split in order to maintain direct access into the District for people at Van Dorn and Franconia-Springfield.

In the end, 6 blue line trains per hour between Franconia-Springfield and Vienna/Fairfax-GMU (or King Street & East Falls Church) in order to maintain connections to National Airport and Alexandria for north Arlington residents (and vice versa), 10 orange line trains per hour from Vienna/Fairfax-GMU to New Carrolton, 10 silver line trains per hour from Tysons(Ashburn) to Largo Town Center, and the additional yellow line split to continue providing one-seat DC service from Franconia-Springfield & Van Dorn.

by Aaron on Jun 30, 2010 1:11 pm • link • report

@ MrS, if you've ever been through Rosslyn at rush hour, it's already congested enough with people switching trains and people getting on/off there. I used to go from Clarendon to Crystal City, and the pedestrian traffic there, while not as bad as Metro Center, is no picnic. Offloading all inbound trains there would add too much foot traffic to an already busy station. Anyone who's ever been offloaded from a crowded orange line train at Rosslyn due to a malfunction would be able to attest to this.

by JS on Jun 30, 2010 1:15 pm • link • report

If Blue goes south over the Yellow Line bridge, what about the downtown stations to the west of there? McPherson and Farragut West are busy during the work day, and Foggy Bottom is the third busiest station overall (stats on that were a few years ago).

by B on Jun 30, 2010 1:26 pm • link • report

@ Aaron: As another person who sees (and is part of) the not-insignificant number of commuters (and tourists) who change from Orange to Blue at Rosslyn in the morning and vice versa in the evening, this plan makes the most sense but I don't know if the existing track configurations would allow it. I can't imagine that people coming from Largo would take a one-seat ride to the Pentagon over a much shorter trip by changing at L'Enfant, though I suppose this change might add to the existing crush of people changing from the Red Line at Chinatown instead of at the much more spacious Metro Center.

by sg on Jun 30, 2010 1:47 pm • link • report

@Amin:
Yes. We have an idea of how many riders change from Blue to Orange or Orange to Blue at Rosslyn. See my post on the topic here:
http://greatergreaterwashington.org/post.cgi?id=4068

Approximately 4000 people transfer from an Inbound Blue to an Outbound Orange or an Inbound Orange to an Outbound Blue during the AM Peak.

Also, how exactly would a Blue Line train routed over the Yellow Line bridge get to Largo? There is no track connection between the Green/Yellow Line to the Blue/Orange Line at L'Enfant Plaza.

And the Silver Line will continue downtown to Stadium-Armory regardless of what happens to the Blue Line. No one coming from Tysons Corner will have to transfer to get to any station currently served by the Orange Line between East Falls Church and Stadium-Armory.

@Dizzy:
I think that's an excellent idea. I'm not sure how much in the way of power upgrades are necessary.

The main reason that the Blue and Yellow Lines operate all 6-car trains is because the demand is generally not there for longer trains.

Also, just to clarify: the Blue Line's current routing via Rosslyn will be dropping from 10 trains/hour to 6 trains/hour.

So it would go from 60 cars to 36 cars. Increasing the remaining 6 trains/hour to 8-cars would mean that there would be a throughput of 48 cars on the Franconia-Rosslyn-Largo route.

@Aaron, @Adam L.
While rerouting the Silver Line so that it does not pass through Rosslyn might solve this problem, it won't solve all the problems.

No matter where you are in the system, you're going to have a 26 TPH chokepoint. Since there are two Potomac crossings, you can have a total of 52 trains entering DC from Virginia minus however many come from Branch Avenue.

Right now that breaks down to:

16 Oranges
10 Blues via Rosslyn
10 Yellows
12 Greens
Total: 48
leaving 4 empty slots

So with an estimated 10 trains/hour coming from the Silver Line, we could put 4 into Downtown via Arlington Cemetery, but the remaining 6 put us over capacity.

So we'd either have to run fewer Silver Line trains or reduce the current level of service on another line. And that puts us right where we are now.

So, in the end, while building two underground wyes is cheaper than a new cross-town subway, it is also less advantageous.

@B:
The stations in the western portion of Downtown (and actually all of the stations on the combined Orange and Blue Lines and on the branches to New Carrollton and Largo) will still have the same number of trains that they have today. They will just be mostly Orange.

by Matt Johnson on Jun 30, 2010 2:06 pm • link • report

Do Metro trains have to have an even number of cars? I always see references to six vs. eight cars. How about seven?

by Vicente Fox on Jun 30, 2010 2:26 pm • link • report

@Vicente Fox:
Yes. Metro's railcars operate in married pairs. They come in lengths of 4, 6, or 8. 2 car trains are not used because there are sections of track where they can be stranded without power.

by Matt Johnson on Jun 30, 2010 2:30 pm • link • report

+1 to Eric F's question above. Isn't there a technical solution to shrinking the 135s switching interval?

by HM on Jun 30, 2010 2:45 pm • link • report

Heh, I just heard that Metro is randomly experimenting with sending Blue Line trains to New Carrollton instead of Largo. I guess that's one way to test out reconfiguring options.

by Lou on Jun 30, 2010 3:13 pm • link • report

Does Metro have a price tag for the Court House-Arlington Cemetery, Arlington Cemetery-L'Enfant Plaza, and Pentagon-Waterfront switches? Would they require additional tunneling? Did the original planners consider these? Are there better names for these switches?

And if the Pentagon-Waterfront switch (from Yellow to Green) ever does get built, it would be a good argument for a station in Potomac Park by the Jefferson Memorial, because otherwise you're going from the Blue Line to the Yellow Line to the Green Line, but without any way to transfer to the Yellow Line. And I think a Jefferson Memorial station would be helpful anyways - certainly it would get more customers than Arlington Cemetery, don't you think? It might even be a semi-convenient spot for some waterfront workers.

by M.V. Jantzen on Jun 30, 2010 3:40 pm • link • report

@M.V. Jantzen:
All three would require tunneling. The ones near Pentagon and L'Enfant would also be being tunneled very close to water, which might introduce some engineering challenges.

Why not call them:
"Rosslyn Wye"
"Pentagon Wye"
"Waterfront Wye"

by Matt Johnson on Jun 30, 2010 3:53 pm • link • report

I've notice when going through the Blue Line tunnel out of Rosslyn towards the airport that the walls are very rough, exposed rock and very close to the trains in some places. There must be some rock in that area that would probably make the tunneling that much more difficult.

by Lou on Jun 30, 2010 4:07 pm • link • report

The most obvious solution is....fix the damns switches!

26 trains an hour is not the best a subway system can do. If places like Moscow and Mexico city have the capacity to safely run 40 trains an hour.....then why cant we? The technology exists. And the last instance I can find online of two trains crashing with deaths in mexico city was in 1975.

Send someone down there, find out what magic switches and signals they use, and buy some.

by J on Jun 30, 2010 4:26 pm • link • report

Check out http://en.wikipedia.org/wiki/Wye_(rail) - this should probably get its own post. Till then, imagine how great it would be for Virginians at Nationals Stadium to have a "wye" south of L'Enfant, so their trains could proceed onto the Yellow Line without a transfer, and without reversing their travel on the same segment of rail.

And the fun part of the Rosslyn/Pentagon/L'Enfant wye route for the Silver line is that it would travel only on segments of rail that are currently at half capacity, by virtue of having only one line using that segment.

Don't dream it, be it!

Or just use the Rosslyn wye and you can have a line connect Dulles to National airport - would that be useful?

by M.V. Jantzen on Jun 30, 2010 5:41 pm • link • report

What about people at Benning Road, Capitol Hgts, Addison RD, Morgan BLVD, Largo who want to go to Alexandria. Why should everybody but them get a one seat ride.

Why not have

Silver line trains go to Largo

Blue line trains to go to Stadium Armory and Largo depending on time of day

Orange and Yellow line stay same.

Construction fixes

Build Wye's at L'Enfant Plaza, Rosslyn, Pentagon, Metro Center

Connect Hunington to Van Dorn so that all lines serve the same stops from Pentagon on south.

by kk on Jun 30, 2010 6:14 pm • link • report

About the 135 seconds to "flip the Rosslyn switch"... I can't imagine it really takes this long. Anyone who has ever stood at the outbound end of the lower platform (toward Franc-Springd and Vienna) can hear the switch. Just stand there an listen for it. Once a train passes through, you hear a quick vibration/buss/grind sound and that's it. I've seen Orange - Blue - Orange trains at p.m. rush hour pass through one after the other with not more than 45 to 60 seconds between each train. Again, go to Rosslyn at p.m. rush and you can hear the switch.

I agree with the previous replies about upgrading the darn switch. In fact, the Orange/Blue line switch at Rosslyn is scheduled to be replaced the second weekend in July. I hope WMATA staff had the foresight to use this upcoming replacement as an opportunity for an upgrade.

by Transport. on Jun 30, 2010 8:20 pm • link • report

Blue Line Separation Starter Project:
http://maps.google.com/maps/ms?ie=UTF&msa=0&msid=
113262488393877820698.00048a48f3605231b7424

Separating the Blue Line is a long term goal for the METRO system as a whole - particularly to alleviate the "Orange Crush" (and upcoming Silver/Orange Crush...) at the Rosslyn station - in addition to offering more crosstown access in downtown DC. However, such a project has been dismissed on the grounds that it would cost billions of dollars to essentially duplicate an existing route, adding capacity but not serving new customers. What has never been discussed is a half mile viaduct separation of the blue line at the the Rosslyn station ONLY using existing right of way, with a new viaduct platform above Lynn Street, and a high-speed high-capacity elevator connecting this platform directly to the existing one below ground. Serving as a "Junior Stage One", such a project would be a tiny fraction of the cost a proposed full separation of the blue line, but respond to the major problem of the existing Orange Crush, as well as responding to the upcoming "Silver Crush" as well (under const silver shares track w orange).

by stevek_fairfax on Jun 30, 2010 9:27 pm • link • report

Matt, thanks for the correction on the number of Blue Line trains... somehow, my eyes glazed over the "just under half" and turned it into "half." Based on current ridership, I think 48 cars/hour could do the job.

Also, if Metro follows precedent, I think they will ultimately end up sending at least some of the Silver line trains on to Largo. Based on their practice a long time ago of signing trains Orange when headed to New Carrollton and Blue when headed to National Airport, even though they were going back and forth along the exact same route, it looks like Metro really doesn't want to have different terminus stations at the same end of a line (e.g. branches). That makes me think they don't want to split Orange Line trains between New Carrollton and Largo.

As for the newly redirected Blue Line/newly branched Yellow line, it's only a difference of two stations either way that are, one would think, almost entirely frequented by locals (with the exception of tourists taking transit to Mount Vernon). I think the confusion caused by introducing the "Yellow Line train to Franconia-Springfield" would be pretty limited.

@Transport. - I too have stood right next to the Welcome to Virginia sign and listened to the switch. You're right in that the audible part of the switch seems to take no more than 10 seconds, after which point the signal changes from Red to Flashing White (my experience is only with switches from Blue to Orange, since I needed to get on the Orange). It would be nice to have someone with technical expertise weigh in on this. Maybe the inbound switch is more complicated than the outbound?

by Dizzy on Jun 30, 2010 9:28 pm • link • report

http://maps.google.com/maps/ms?ie=UTF&msa=0&msid=113262488393877820698.00048a48f3605231b7424

by stevek_fairfax on Jun 30, 2010 9:29 pm • link • report

@Matt Johnson:
The engineering challenge of building the wye tunnels between the C and L routes north of Pentagon would be no more difficult then it was to excavate and build the cut and cover tunnels that are already there. The only challenge today is connecting those tunnels to the existing tunnels near the Water Entrance to the Pentagon.

@Lou:
All of the tunnels from Foggy Bottom to Court House and from Rosslyn to the portal north of Arlington Cemetery are bored through the bedrock. With today's technology it would be easier. The tunnels were mined back in the late 1960 and early 1970s using the drill and blast method.

@J, Transport:
It is not the switches in the junction on the south end of Rosslyn that are the limiting factor. It is the speed at which trains can be discharged and boarded at station platforms. The signaling system is designed for 90 second headways. With no passengers discharged and boarded the trains WMATA would have no problem running trains at 90 second headways.

by Sand Box John on Jul 1, 2010 12:09 am • link • report

@Joshua Davis writes: "However you slice it, the silver line is quite likely to add more than 4 additional trainloads worth of people per hour. It's not going to be fun. Arlington needs to add office space and put a brake on additional housing, it seems to me."

::: Agree completely. ::: Also, development of the Dunn-Loring, Vienna, and West Falls Church status could be done NOW without waiting for the Silver Line. MetroWest has landed cleared at Vienna but has stalled waiting for funding. Dunn-Loring has started doing stuff to make the area more walkable and a nice place to grab something to eat, but could be accelerated.

With all the rush about the FAR-OFF possibilities of Tysons, efforts to improve EXISTING Vienna, Dunn-Loring, and the Falls Churches seems to have been overlooked.

@J writes: "The most obvious solution is....fix the damns switches!"

Agreed, that would seem to be the obvious solution. I've been on the Orange/Blue Line westbound during rush hour and was seriously depressed to see only 6-car (vs. 8-car) trains go by every 5-7 minutes.... what's up with that? Meanwhile the trains are so full at Farragut West and Foggy Bottom, even before Rosslyn, that people cannot get on and some are even collapsing of heat exhaustion!

@Joshua Davis - your logic is flawed. You said West Falls Church (18th most busy station at rush hour) but that's NOT on the Silver Line. Vienna is the 3rd most busy station at AM rush hour, also not on the Silver Line. Silver Line will ADD additional people who normally don't take the Metro because the Orange Line because it's too far from their homes, but the Silver Line is acceptable, so it's not a SPLIT, it's a SPLIT PLUS MORE. Silver-Orange between EFC and Rosslyn will be a nightmare unless the they're all 8-cars and running FASTER.

by A. Walker on Jul 2, 2010 7:03 pm • link • report

How about routing some silver line trains (3 out of 10?) through the west falls church yard to dunn loring and vienna? (or spend some money and build an elevated single track wye to west falls church station?) This will offer central fairfax residents direct rail connection to Tysons and IAD and maintain more blue line trains through Rosslyn.

by hw on Sep 23, 2010 5:29 pm • link • report