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Metro FAQ: Why no peak Yellow Line past Mt. Vernon Sq.?

Periodically, we get questions about some of the nuances of Metro's service and operations. Some of these came up in a recent thread. While some of you know the answers, many don't. Therefore, we decided to review some of these topics.

In December 2006, Metro began extending Yellow Line trains to Fort Totten off peak. It started as a pilot, but increasing demand for Metro in the mid-city made the extension permanent. If the project was so successful, why not have the Yellow Line run to Fort Totten all the time?

Photo by the author.

There are several technical hurdles that would need to be dealt with before Metro could run the Yellow Line to Fort Totten during rush hour:

Empty Pockets
The primary reason is that Fort Totten does not have a pocket track. A pocket track is a third track located between the two main tracks. These allow trains to leave the mainline, change ends, and then wait for clearance for the other track without disrupting through trains on either track.

There are only a few pocket tracks in the Metro system. They are located:

  • Red: North of Grosvenor
  • Red: North of Farragut North
  • Red: North of Silver Spring
  • Orange: At West Falls Church
  • Orange and Blue: East of Stadium-Armory
  • Blue and Yellow: At National Airport
  • Yellow and Green: North of Mount Vernon Sq.

Silver Spring pocket track. Photo by the author.
Currently, the pockets at Silver Spring and Grosvenor are used for the short-turning Red Line trains which don't run all the way to the end of the line. The Mount Vernon Square pocket is used to terminate Yellow Line trains during rush periods. The other pockets don't see as regular use, although the West Falls Church pocket is used for some trains being brought into or out of the rail yard there.

Of course, pockets aren't the only place where trains can change tracks. Crossovers are located throughout the rail system, generally between every other station or so, though that varies based on station spacing. Since trains can crossover at any of these switches, they can be candidates for short turning. This is the case at Fort Totten, where a simple diamond crossover allows Yellow Line trains to turn back off peak.

During rush hour, the Green Line operates at a 6 minute headway. The Yellow Line also operates every 6 minutes during peak. That means that the combined segment of the Green and Yellow Lines—between L'Enfant Plaza and Mount Vernon Square—sees a train every 3 minutes. With a pocket track, this is not an issue. Three minutes between trains is plenty of time to reset the switches and keep the subway moving.

But without a pocket, the Yellow Line train would have to sit on the mainline while it changed ends and waited on clearance. At three minute headways, that would create massive delays.

The current setup at Fort Totten works because off-peak the Green and Yellow Lines each run at headways no better than 12 minutes. With 6 minutes between trains, there's enough time. Even so, northbound Green Line trains are still often held on the platform at Fort Totten because the Yellow Line train is waiting for the southbound Green Line train to clear before crossing over.

Fleet Size Matters
The other technical hurdle to extending the Yellow Line to Fort Totten during rush hours is that there aren't enough railcars. The longer a rail line is, the more railcars are needed to operate the line at the same headway. Fort Totten might not feel like it's that far from Mount Vernon Square, but a peak period extension of the Yellow Line would require 30 more railcars than are currently used.

Metro doesn't have that many extra railcars. An extension would either have to wait for extra cars to be purchased and built, or it would require the cannibalization of railcars from other lines.

Metro is currently in the process of procuring the new 7000 series railcars, but those cars won't be enough. The initial contract is for 428 cars, although it is expandable. These cars will be enough for the Silver Line (128 cars) and to replace the 1000 series (300 cars). In 5 years or so, when they've been delivered, further fleet expansion might make a full-time Yellow Line extension feasible.

Money Matters
It would cost $3 million more per year to operate the Yellow Line to Fort Totten during rush hour. That's not pocket change for WMATA's operating budget. In fact, this year, WMATA seriously considered eliminating the off-peak Yellow Line extension to save $3 million per year.

But the capital costs are an obstacle too. In 2006, WMATA estimated that the capital costs of a full-time Yellow extension would be $150 million. That would pay for an underground pocket track, signal system improvements, new maps, and railcars.

Some of these improvements are probably good ideas regardless of what happens with the Yellow Line. A new pocket track at Fort Totten would improve redundancy in the system. New railcars would ease crowding throughout the system.

But even if Metro had the resources to get started immediately, it would be several years before the full-time extension would be feasible. The railcars wouldn't be on site until after the Tysons and Dulles cars and the 1000-series replacements. And digging a new underground pocket track would take several years to complete and would be disruptive to Green Line riders along the way.

Of course, that doesn't mean it won't ever happen. While there are no plans currently, the Mid-City has been growing tremendously, and Columbia Heights has seen dramatic ridership growth over the past year or so. But ridership is still within the ability of the Green Line to provide. Within a few years, some Blue Line trains will be calling at Mid-City and northern Prince George's stations, and that will also help to alleviate crowding. But that's a topic for another post.

Matt Johnson has lived in the Washington area since 2007. He has a Master's in Planning from the University of Maryland and a BS in Public Policy from Georgia Tech. He lives in Greenbelt. Hes a member of the American Institute of Certified Planners. He is a contract employee of the Montgomery County Department of Transportation. His views are his own and do not represent those of his employer. 


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Also the fact that in the morning, when heading North, yellow line trains empty except for maybe 2-3 people per car at Gallery Place.

by DMC on Jun 28, 2010 1:06 pm • linkreport

It's a minor quibble but I think the northbound line/destination combos are incredibly confusing on on those tracks. As someone who uses a station between Mt Vernon Sq and Ft Totten. As best I can tell, there are:
Green --> Greenbelt
Yellow --> Ft Totten
Yellow --> Mt Vernon Sq, and (I swear, after Nats games)
Green --> Mt Vernon Sq.

I wish they would make every northbound train "Green" at L'Enfant plaza, and leave them that way till they turn around.

by mark on Jun 28, 2010 1:19 pm • linkreport

You've intrigued me with the comment, "Within a few years, some Blue Line trains will be calling at Mid-City and northern Prince George's stations, and that will also help to alleviate crowding. But that's a topic for another post."

When's this post coming? I'm curious about this because I haven't heard of it. Maybe I've not been paying attention.

by Ed Hoover on Jun 28, 2010 1:21 pm • linkreport

@Ed Hoover
That post is just about ready to go up. Right now, WMATA has no plans to reroute Blue Line trains, however, once the Silver Line opens, some Blue Line trains (about 4/hour during rush hour) will run Franconia-Pentagon-L'Enfant-Greenbelt.


by Matt Johnson on Jun 28, 2010 1:23 pm • linkreport

@Matt Johnson - thanks, I think I missed that. Makes sense, really, and I assume it wouldn't cost much more, if any. But I'll wait for the post ;)

by Ed Hoover on Jun 28, 2010 1:26 pm • linkreport

One nitpicky point...

I don't have the metro schematic anymore, but would the interchange track that connects the Red Line south of Ft Totten to the Green line northeast of it get in the way of a pocket track? Also, what if Yellow Line trains did go north to Ft Totten, and every other Green Line Train followed down the Red Line to make a Greenbelt-Grosvenor run? Takoma and Silver Spring would lose some service in this instance, but I'd be curious to examine the idea. Remember Metro did run Farragut North to Greenbelt Service before the Georgia Ave. stretch of the Green Line was complete back in the late 90's, using that track. The reduced thru-service on the Green Line could give the Yellow Line trains time to turn around. I wish that Metro had more "off-ramps" like this one, to allow for more one seat rides thru the downtown core, especially from the Red Line, which does a useless "U" rather than connecting with something on the other side of town.

by Joe on Jun 28, 2010 1:26 pm • linkreport

A few times at Pentagon, I've seen Yellow Line trains that said they were going to Greenbelt. Are those for real, or signed incorrectly, or what? (I don't go that far north, so I never found out what was going to happen.)

by Scott F on Jun 28, 2010 1:27 pm • linkreport

@Joe - as someone who used to live in Wheaton, I'd fight that proposal. That section of the Red Line gets screwed more than any other part of the line, despite what Metro says. Trains turn back way more frequently at Silver Spring than they do at Grosvenor, it seems - I highly doubt it's a true Silver Spring-Grosvenor run so much as it is a Silver Spring-Glemont run with the occasional (i.e., every fourth train) actually stopping at Grosvenor.

by Ed Hoover on Jun 28, 2010 1:31 pm • linkreport

@Scott F

The original Metro plan always had Yellow line trains running all the way to Greenbelt - it's just never been implemented due to a shortage of railcars.

However, they do occasionally run Yellow line trains to Greenbelt. This seems to happen exclusively on weekends, and I'd imagine it has to do with getting trains to the Greenbelt Yard - if you're running them that way, might as well keep 'em in service.

by Alex B. on Jun 28, 2010 1:31 pm • linkreport

@Scott F:
At the beginning and end of the morning and evening rush hours, 4 trains are scheduled to travel from Greenbekt to Huntington or vice-versa. This is because those trainsets are stored at the Greenbelt rail yard.

It is, therefore, possible to catch a Yellow Line train from Greenbelt. In fact, even the Trip Planner recognizes this. But there are only a few trips per day.

For example, try planning a weekday trip from Greenbelt->Huntington at 9:02 AM.

by Matt Johnson on Jun 28, 2010 1:33 pm • linkreport

Metro seems to think a pocket track is feasible north of Fort Totten. After all, they studied it in the Yellow Line realignment report.

The connector track (B&E Connector) diverges from the Red Line in between the north- and southbound tracks south of Fort Totten. It merges *only* with the northbound Green Line track. After about 600' (1 train length), the Green Line encounters a diamond crossover.

In order for a Green Line train coming from Greenbelt to access the Red Line southbound, it would have to cross onto the northbound track and run for a station length southbound on the northbound track before diverging to head onto B&E Connector.

by Matt Johnson on Jun 28, 2010 1:39 pm • linkreport

I think it would be an interesting study to recreate the Metro system map at various milestones during its development. Maybe that's already been done (?). For instance before each line came into existence. On the current map the Yellow Line looks extremely redundant (it only has two of its own stations!). But seeing the original set of stations that each line served might make an interesting study.

And somewhat related, with all the studies about fleet size and train timing, what would happen if the Yellow Line were to go away? Or be repurposed to just serving Huntington - Arlington Cemetery? There is a crossover at the Cemetery, but with the tracks only 14 feet apart, is there room to move the tracks and build a pocket? This would be in conjunction with the reordering of some Blue Line trains over the bridge.

I imagine there are technical reasons things like that can not be done, but studying the system schematic makes you think about possibilities.

by Lou on Jun 28, 2010 1:41 pm • linkreport

@Lou - Search this blog; I seem to remember there being a click-through version of that where it was "built" before your eyes as you clicked.

by Ed Hoover on Jun 28, 2010 1:45 pm • linkreport

For the history of Metro, see:

by Matt Johnson on Jun 28, 2010 1:46 pm • linkreport

@ Lou

Is this what you are looking for?

by Kevin H. on Jun 28, 2010 1:46 pm • linkreport

Yeah, those are great maps. It would take a long time to analyze all the changes. I had no idea National was once an Orange Line stop.

by Lou on Jun 28, 2010 1:52 pm • linkreport

National Airport was not *really* an Orange Line stop. The thing was, the C&D lines opened from National Airport (Blue) to New Carrollton (Orange). There was no need for Orange Line trains to run from New Carrollton to Rosslyn and then terminate while Blue Line trains ran from National Airport to Stadium Armory and then terminate.

At the same time, they didn't want riders to get used to the wrong colors. So during that period, trains colors were based on where they were going, so that people would get used to the color matching the destination.

So a train leaving National Airport would be an "Orange Line train to New Carrollton". While a train leaving New Carrollton would be a "Blue Line train to National Airport".

Later, in 1980, when the K Route opened to Ballston and the G Route opened to Addison Road, the ridership was unbalanced, so trains ran from New Carrollton to National Airport and from Addison Road to Ballston. But they were signed so that the colors matched their destination. (The Ballston was the "end" of the Orange line and the "beginning" of the Blue Line. Same for the other terminals.

by Matt Johnson on Jun 28, 2010 1:58 pm • linkreport

@Matt - that's always been fascinating to me, those little "workarounds" or whatever you want to call them. I first came to Washington as a 10-year-old in 1986, so that slide show is interesting to me; I can see what it looked like back then. I came again, in high school, in 1991, so again, I can see what the system was when I was there (since I don't really remember).

Now that I know the system intimately, it's fascinating to learn of the different routings and other idiosyncrasies of its creation.

by Ed Hoover on Jun 28, 2010 2:03 pm • linkreport

Once the 7000 series cars have been delivered, ostensibly as 1000 series replacements, could the 1000 series cars be kept in service for a few more years to, for example, run the Yellow Line to Greenbelt at all times?

by jim on Jun 28, 2010 2:24 pm • linkreport


National airport is not a pocket track anymore: The southbound track is not connected anymore. Which leaves me wondering is the middle track ever used nowadays?

Nice article as usual i was only nitt-picking here!

by Vincent Flament on Jun 28, 2010 2:25 pm • linkreport

@Vincent Flament:
Actually, the National Airport pocket (what else should I call it?) is connected to the southbound track, but only on the south side of the station, where it is not connected to the northbound track.

So the only way a train can enter the National Airport pocket is by wrong-railing (nortbound on the southbound track or southbound on the northbound track) from the nearest crossover or passing it and then changing ends.

They usually use it to demonstrate new or modified cars to reporters.

by Matt Johnson on Jun 28, 2010 2:28 pm • linkreport

I guess it could be called a half-crossover.

by Alex B. on Jun 28, 2010 2:32 pm • linkreport

@Alex B.
Perhaps a "torn" pocket.

by Matt Johnson on Jun 28, 2010 2:32 pm • linkreport

How long before Homeland Security tells you to take down this post, I wonder. (At least you didn't post a map, phew.) Sie wissen zu viel!

by M.V. Jantzen on Jun 28, 2010 2:35 pm • linkreport

@M.V. Jantzen:
Mensch! Du kannst mir dutzen.

And since when is knowledge a crime? I'm not afraid of the Sicherheitsapparat.

by Matt Johnson on Jun 28, 2010 2:41 pm • linkreport

Actually, I'm not sure if Metro would have to do any digging to put a pocket track past Fort Totten. They could put it just south of West Hyattsville instead. Of course, I'm not sure if the curved track makes it more difficult. Also, it's elevated, so it's not quite as easy as at-grade. But like I said, no digging.

And even if they do put it underground, at least they won't have to worry about disrupting roads or taking private property like houses. The entire tunnel there is under a park, and most likely cut-and-cover.

by Tim on Jun 28, 2010 3:03 pm • linkreport

The area south of West Hyattsville is a wetland area. It would probably not pass muster when it came to the environmental test.

You are correct that the tunnel would be cut-and-cover.

by Matt Johnson on Jun 28, 2010 3:04 pm • linkreport

For anybody who is interested in details, there exists an online detailed schematic of the Metro system. It isn't completely up-to-date as it doesn't reflect the reconfiguration at National Airport noted by others (the former pocket track is now accessible only against current of traffic in both directions and has been downgraded from a station track to a siding used for occasional daytime storage of on-track maintenance equipment between nocturnal work windows).

You might ask: why did they do that? The puzzle switch at the N end was not well designed, might not have been perfectly installed or maintained, and ended up implicated in more than a few minor derailments. With direct fixation track it's more than a bit of a nuisance to rebuild it and since trains don't turn back there any more WMATA seems to have concluded it would be easier to go in there once to pull out the problem switch, rather than to keep going in there to put it back together after each derailment.

That, and the former piece of Red Line trackage left behind by when the New York Avenue station came into service, are Metro's first two track abandonments.

by intermodal commuter on Jun 28, 2010 3:30 pm • linkreport

I have an off-topic question that I bet you'll know the answer to. I travel from Columbia Heights to Dunn Loring. On average, is my trip shorter by changing only at L'Enfant, or by changing at Gallery Place and Metro Center? Does the answer change for peak vs non-peak? Thanks!

by jcm on Jun 28, 2010 3:35 pm • linkreport

I forgot to say thanks for the thorough answer to the yellow line termination question, which has also had me curious!

by jcm on Jun 28, 2010 3:37 pm • linkreport

Well, it depends on a couple of factors.

The travel time between Gallery Place and Metro Center is only about 1 minute. It's about 2 or 3 minutes from Gallery Place to L'Enfant and 3 or 4 minutes from L'Enfant to Metro Center.

With the Red Line operating about 2.5 minutes apart during peak, and probably around 1 minute to navigate Gallery Place and Metro Center, that means:

Trip A: Columbia Heights->L'Enfant->Dunn Loring
Trip B: Columbia Heights->Gallery Pl->Metro Center->Dunn Loring
Station transfer time assumed to be 1 minute.
Wait time assumed to be half the headway.

Trip A

  • Columbia Heights->L'Enfant Plaza: 9 mins
  • Xfer time, L'Enfant Plaza: 1 min
  • Wait time: 2 mins
  • L'Enfant Plaza->Dunn Loring: 30 mins

Total Time, Trip A: 42 mins.

Trip B

  • Columbia Heights->Gallery Place: 8 mins
  • Xfer time, Gallery Place: 1 min
  • Wait time: 1.25 mins
  • Gallery Place->Metro Center: 1 min
  • Xfer time, Metro Center: 1 min
  • Wait time: 2 mins
  • Metro Center->Dunn Loring: 25 mins

Total Time, Trib B: 39.25 mins.

So it appears you could save around 3 minutes. But it would all depend on how your transfers worked out.

And transferring twice can create problems. Getting on the Orange Line later, for instance, might make it harder to get a seat. Congestion at Gallery Place might make you miss the Red Line train already on the platform or whatever.

The point is that you *can* save several minutes at peak. It doesn't mean that you will. Also, I would advise not doing this off-peak, because trains run less frequently.

by Matt Johnson on Jun 28, 2010 3:51 pm • linkreport

Thanks Matt! I knew you'd be able to work it out.

by jcm on Jun 28, 2010 3:56 pm • linkreport

@jcm - Not your exact question, but the fastest commute for you would be to bike to McPherson Square and just ride the Orange Line. I live in Park View (just east of Columbia Heights) and often meet my Virginia friends that way.

by Scott F on Jun 28, 2010 4:00 pm • linkreport

I had that same transfer dilemma last Tuesday afternoon. I decided to get off at Gallery Place and get on the Orange at Metro Center instead of staying on the Green to L'Enfant. I think, based on how long I waited for the two trains, that I made the "right" choice. Funny, in the morning during rush hour when I was making that trip in reverse, the thought never crossed my mind to do anything other than just the one transfer at L'Enfant.

by Lou on Jun 28, 2010 4:04 pm • linkreport

On the detailed Metro schematic posted by intermodal commuter, did anyone else notice the "future tracks" breaking off south of the Pentagon? Anyone know the story there?

by David T on Jun 28, 2010 4:20 pm • linkreport

@Scott F That's a really good idea for the beginning of the week for me. I actually leave my bike in a locker at Dunn Loring during the week to get back and forth to the office, but that'd definitely work to get out there. I ride all the way home from Tyson's on the weekend, and it's actually faster than taking the train, or even driving during rush hour.

by jcm on Jun 28, 2010 4:32 pm • linkreport

@jcm: The always-proposed-sometimes-planned-never-built pedestrian tunnel between Gallery Place and Metro Center might solve your problem, especially off-peak (probably during peak, too, but the tunnel would probably be at the elevation of the red line, so you'd have to go up a level, then down. In fact, since both of the lower platforms at the stations are island platforms, you'd have to change elevation in some way no matter what).

by Tim on Jun 28, 2010 4:32 pm • linkreport

@David T

The Adopted Regional System (1968) had the Columbia Pike line as a "future extension", even though everyone knew it wouldn't be built. The side tunnels at the Pentagon were where that line would have connected.

by jim on Jun 28, 2010 4:41 pm • linkreport

@David T: I'm almost certain that refers to the Columbia Pike line. There's a stub tunnel off at least the outbound tunnel, but no tracks and I'm pretty sure nothing on the inbound side.

And at this point, building the line is not a serious proposal at all.

by Tim on Jun 28, 2010 4:41 pm • linkreport

@David T:
Pentagon Station has two tunnel "bellmouths" south of the station. These were constructed to mollify the Arlington County government, which was agitating for a Columbia Pike subway toward Annandale or Lincolnia.

No plans were made to actually construct the subway, but it was decided to create a tunnel provision to allow for the construction should funding become available later.

It would, however, be difficult to fit trains into the schedule. Pentagon can only handle 26 trains per hour. Currently, 20 trains are scheduled, 10 Yellow, 10 Blue. The 10 Yellows meet 12 Greens at L'Enfant, which also has a 26 tph capacity. That leaves room for 4 trains. And the Silver line will require that 4 Blue Line trains eventually be routed via L'Enfant.

That means that there is room for exactly 0 tph to be added to Pentagon once the Silver Line opens, unless we reduce the number of trains on the Blue or Yellow lines.

by Matt Johnson on Jun 28, 2010 4:41 pm • linkreport

Right. Any Metro Line along Columbia Pike will probably require another platform at Pentagon (just as the new Blue Line proposals involve another platform at Rosslyn). That doesn't mean those stub tunnels would be wasted, however - they could very easily be used for non-revenue train movements.

by Alex B. on Jun 28, 2010 4:49 pm • linkreport

@Alex B.

Any Metro Line along Columbia Pike will probably require another platform at Pentagon

It would need another river crossing, too. One of the virtues of the Separated Blue Line is that it would make a Columbia Pike Line possible. Since there could be no more than 15 tph Blue Line trains running along it (since that's all that could leave the Pentagon, assuming Yellow Line trains continue at 10 tph), there'd be room for at least 10 tph from somewhere else to join that line after the Pentagon. Perhaps Metro should try to sell Virginia on a combined Columbia Pike/Separated Blue Lines proposal.

by jim on Jun 28, 2010 6:03 pm • linkreport


And for anybody who hasn't seen it, the same site (not mine) also has a map of the 1968 Adopted Regional System - yet another cartographical time capsule.

by intermodal commuter on Jun 28, 2010 6:47 pm • linkreport

So does the last Yellow Line to Ft Totten get there at 3PM or leave Huntington at 3PM

Why would a Columbia Pike line cause many problems at Pentagon when/if a line is ever built you could just connect Eisenhower Avenue & Huntington to the blue line; by having the blue line go to Huntington & then making a U turn to Van Dorn Street and resuming then normal route

by kk on Jun 28, 2010 7:50 pm • linkreport

I'm all for having more Blue Line trains take the Yellow Line bridge into downtown Â… but why not just switch the color designation back to the way the system was originally designed, with the Blue Line going to Huntington? The 395 commuters at Franconia-Springfield could use a more direct link downtown, and it would be nice to be if it were easier to be able to visit the mall there on the weekends.

by Omar on Jun 29, 2010 12:17 am • linkreport

And another track schematic from the site listed above which includes the Dulles extension:

by Aaron on Jun 29, 2010 3:26 pm • linkreport

Man, they barely run the Yellow line as it is. I hate when they run the line to Greenbelt, because it means fewer turnarounds to the busy parts of the lines. I'd be thrilled if the Yellow line terminated at Mt. Vernon Square all the time.

by Rebecca on Jun 29, 2010 3:49 pm • linkreport

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