Greater Greater Washington

Posts about Blue Line


Did Rush Plus depress Blue Line ridership?

To make room for new Silver Line trains at the Rosslyn bottleneck, WMATA has reduced the number of Blue Line (and Orange Line) trains and added Yellow Line trains. A group calling itself Save the Blue Line claims that a similar change in 2012 caused riders to stop using Metro. Is that accurate?

Graph from Save The Blue Line.

In June of 2012, Metro started a new service pattern in Virginia. To make way for more Orange Line trains and more service in north Arlington and Fairfax, the agency started sending some "Blue" Line trains from Franconia over the Yellow Line bridge to Greenbelt, labeled "Rush Plus" Yellow Line trains.

In the two years since, has that lowered ridership?

It's hard to say with any certainty. Ridership at the stations south of Pentagon is lower than it was before Rush Plus. On the other hand, ridership was already dropping before Rush Plus started.

There's actually an error in the Save The Blue Line graph: while the arrow suggests Rush Plus started between the 2011 and 2012 data points, the 2012 data is actually from a count in May, before Rush Plus started. The arrow should actually point one more space to the right, and therefore the drop you can see on the graph began before Rush Plus.

Did Rush Plus contribute to the ridership drop?

We cannot prove causation from correlation, but perhaps we can glean some insight from the numbers.

If we look just at boardings from Van Dorn Street and Franconia/Springfield, we can see a noticeable dip starting in about 2010. It continues into 2013 before leveling off a bit.

This and all subsequent graphics by the author.

From 2011 to 2012 (one year before Rush Plus), ridership at Van Dorn and Franconia declined 3.94%. That drop contrasted with a systemwide increase in ridership of 0.13%. So before Rush Plus the Blue Line (the end at least) was already losing riders compared to the rest of the system.

The May 2013 number is the first data point after Rush Plus started. In the period from May 2012 to May 2013, ridership at Van Dorn and Franconia shrank 7.81%, significantly more than the systemwide decline of 2.57%.

The ridership decrease was somewhat attenuated between 2013 and 2014, where at Franconia and Van Dorn it dropped only 1.17% compared to 0.55% systemwide.

If we look at all the stations most affected by Rush Plus, from Pentagon south, we see similar trends, though they're less strong.

Prior to Rush Plus, average daily boardings at Pentagon and the stations to the south (to Huntington and Franconia/Springfield) declined 3.68% over the 12 months from May 2011 to May 2012. Following 11 months of Rush Plus, ridership on this section had dropped 4.49% (compared to 2.57% systemwide).

So the data do show that ridership on the Blue and Yellow lines south of Pentagon has been lower since Rush Plus was implemented. But the ridership was already shrinking before Rush Plus.

It's certainly possible that Rush Plus exacerbated the ridership loss, but there's no way to tell for sure with the data available.

Even if Rush Plus did cause a significant drop, there's little WMATA can do. The tracks between Rosslyn and Stadium/Armory are operating at their capacity of 26 trains per hour. With Silver Line service starting this weekend, something has to give. With higher ridership in the Rosslyn-Ballston corridor, WMATA has decided to shift some Blue Line trains onto the 7th Street subway.

The number of trains at Franconia and Van Dorn hasn't decreased. Passengers still have the same number of trains going downtown. But fewer of them go to Rosslyn. For getting to the western end of downtown, some riders will now be better off transferring at L'Enfant Plaza.

WMATA planners are hoping to relieve pressure in the future by upgrading the system to handle more 8-car trains and building new Blue Line platforms at Rosslyn. Future phases could take the line across downtown.

Without more railcars, power stations, and core capacity, WMATA has little alternative but to reduce Blue Line service. That's why riders frustrated at losing Blue Line trains can have the best impact by lobbying their elected officials to fund Metro's plans for 8-car trains, a second Rosslyn station, and eventually a new crossing into DC.


A "wye" is out, but a second Rosslyn station may make more Blue Line trains possible

Metro's planners have been studying ways to deal with the capacity crunch at Rosslyn station. A track connection from Court House to Arlington Cemetery isn't possible, but a second station for the Blue Line is, and could be built by 2025.

Each Metro track segment is limited to 26 trains per hour (TPH). At Rosslyn, where the Blue, Orange, and (soon!) Silver Lines come together, this limits the number of trains on each line. In 2012, Metro reduced the number of Blue Line trains to allow more Orange Line capacity. Later this month, the number of Blue Line trains will decline even more to make room for the Silver Line.

Two possible fixes for Rosslyn. Image from WMATA.

There's really no way to alleviate this crunch without additional track capacity. Eventually, it's likely that a second subway across downtown will be necessary to handle the ridership. Metro is currently exploring the idea of building a new loop line through the central city. A new subway would allow Orange and Silver lines to each have 13 slots, and the Blue Line could also to have increased service up to 13 TPH.

Earlier, Metro was looking at two ways to address the capacity constraints. One concept was a "wye" track connection, to allow trains coming from Court House to turn south and go toward Arlington Cemetery and vice versa. The follow-up study this year, though, determined that building foundations make this option impossible.

Potential location for a second Rosslyn station. Image from WMATA.

The other option, though, is feasible. It would require building a second station one block west of the current Rosslyn station. This new platform would connect to the existing Rosslyn station with a pedestrian tunnel. At least initially, only the Blue Line would use it. The Orange and Silver lines would stay in the current station.

If built, this would mean that the Blue Line would only operate between Franconia-Springfield and Rosslyn (though some Yellow Line trains might still start and end in Franconia as they do today). That would mean that, at least until the line is extended across the Potomac, Blue Line riders would need to transfer to an Orange or Silver line train at Rosslyn to get downtown. But all the lines at Rosslyn would be coming more frequently than they do today, which might alleviate the inconvenience of changing trains.

These diagrams I made last year show how the new station (and the infeasible wye) could work.

View peak service levels: Pre-Silver Line   With Silver Line
Possible solutions: Blue Line terminal Wye (rejected)  

Note: Since this graphic was created in 2013, Metro has announced there will be 5 TPH per hour on the Blue Line once the Silver Line opens, rather than 6 as shown here.

The wye would have allowed for more trains on the new Silver Line tracks and given riders from Alexandria and south Arlington a one-seat ride to Court House, Clarendon, etc. (if they caught the train every ten minutes going that way), but it also would have made service more complex, added chances for delays, and not fit in as well with a future Potomac River crossing. A new Rosslyn terminal would hopefully be just the first segment of a crosstown subway through Georgetown.

Possible extension to Georgetown.

Right now, Metro's planning staff is recommending the proposed station be moved forward for project development funding, which essentially means that they want it to get money for more detailed study. But the project is in the Metro 2025 plan, so planners anticipate that this could be opened within 11 yearsif the jurisdictions, particularly Virginia and its cities and counties, are willing to pay for it.

For the next few years, the capacity crush at Rosslyn is likely to get worse. But this project might be the light at the end of the tunnel for Blue, Orange, and Silver line riders.


Ask GGW: Why can't Metro keep more trains on the Blue Line?

With Silver Line opening soon, Metro is reducing the number of Blue Line trains running between Pentagon and Rosslyn. Reader Daniel W. wants to know why Metro is doing this.

Photo by Adam Fagen on Flickr.
Could GGW offer some insight into why Metro is increasing headway on the Blue Line instead of clearing room in the tunnel by running fewer Orange Line trains but running them with eight cars? WMATA can service the same number of Orange Line riders with one third fewer trains by simply running trains at system capacity.

The current situation is fairly complex. Each Metro line has a capacity of 26 trains per hour (TPH). Right now, the combined Blue/Orange line between Rosslyn and Stadium/Armory is operating at that limit. When the Silver Line starts operating later this month, both the Blue and the Orange lines will see fewer trains to make way for the Silver Line. That much is inevitable.

But the Blue Line reduction is more severe for two primary reasons. First, there's simply more demand for trains coming from north Arlington, so Metro wants to give the majority of the slots to the Orange and Silver lines. The other reason is that the line coming up from Alexandria and southern Arlington splits at Pentagon. Blue and Yellow line riders have two options for getting into downtown. But for the Orange and Silver lines, the only place they can be routed is via Rosslyn.

Many Blue Line riders are understandably upset about having longer waits for a direct train to the western part of downtown. Now, it may often be faster for riders to take the "rush plus" Yellow Line from Franconia and transfer at L'Enfant. But without a separated subway for the Blue Line, there's not much WMATA can do to increase capacity.

Comparing capacity

What does the current breakdown look like?

View peak service levels: Pre-Silver Line   With Silver Line
Note: This graphic was originally created in 2013. Since then, Metro has announced there will be 5 TPH per hour on the Blue Line once Silver opens, rather than 6 as shown here.

Right now at Rosslyn during peak hours, there are 19 inbound Orange Line trains and 7 inbound Blue Line trains each hour. That means there's an inbound train about every 2 and a half minutes.

Of the Orange Line trains, about 40% are 8 cars long and 60% are 6 cars. All of the Blue Line trains are currently 6 car trains. That means that each hour at Rosslyn, there are roughly 42 inbound Blue Line cars and 130 inbound Orange Line cars. This means a total of 172 inbound cars per hour.

Once the Silver Line opens, the distribution will change. Starting on July 28, the mix at Rosslyn will be 11 Orange Line trains each hour, 10 Silver Line trains per hour, and 5 Blue Line trains per hour.

All of the Silver Line trains will be 6 cars in length. The proportion of Orange Line cars is not expected to change, so it will remain about 40% 8-car trains. The Blue Line will operate with half of its trains as 8 car sets.

That means that at Rosslyn, there will be 35 Blue Line cars inbound each hour, a reduction of 7 cars. The Orange Line will also see a reduction, with only 74 cars per hour. The Silver Line will have 60 cars inbound each hour. Now, since the Silver and Orange share in northern Arlington, riders at stations like Clarendon will see 134 inbound cars each hour, which is a very slight increase. Overall, at Rosslyn, that will mean 169 cars inbound each hour (which is a slight decrease).

So, even though the transit agency is reducing Blue Line frequency in order to fit more trains coming from northern Arlington, the change in the length balance of those trains means that essentially passenger capacity is staying the same. It's only increasing by 4 cars per hour. And of course, it's dropping by quite a bit for the stations on the Orange Line west of East Falls Church (from 130 today to 74), though that section of the line is less crowded than the parts closer to the core.

Alternate solutions

Daniel's question is specifically whether WMATA can have the same capacity by increasing the length of Orange Line trains rather than reducing frequency on the Blue Line.

If WMATA kept the same number of Blue Line trains as there are today7 TPH each 6 cars in lengththe inbound Blue would have 42 cars per hour. The number of Orange Line trains would still have to change to accommodate the Silver Line, so let's assume the remaining 19 slots are distributed 10 to the Orange Line, with all 8-car trains, and 9 to the Silver Line, with all 6-car trains.

There would then be 80 inbound Orange Line cars per hour and 64 inbound Silver Line cars per hour, for a total of 144 cars per hour coming through northern Arlington. That would mean a total of 186 cars per hour inbound at Rosslyn, which is significantly more than today.

However, this solution would actually require Metro to use more cars in daily service, and right now, there simply aren't enough. The Silver Line requires more cars to run, since Wiehle Avenue is so far out. The opening of the new line is already stretching Metro's fleet. There will be more wiggle room sometime soon, once the first 64 7000-series cars arrive, but that milestone is probably more than a year away.

The other issue is that Metro still needs upgrade power systems on all the lines to enable more 8-car trains to operate. Right now, even if Metro had enough cars, there isn't enough traction power capacity to run all 8-car trains, though the agency is slowly working to upgrade traction power substations throughout the system.

Metro does anticipate running 100% 8-car trains in the near future. But being able to do so is dependent on being able to finance more 7000 series railcars. Right now, the local jurisdictionswho pay for capital upgradeshaven't ponied up enough money for that to happen, but there's still time.

WMATA expects ridership to continue to grow. More people ride the Orange Line in northern Arlington than ride the Blue Line between Pentagon and Rosslyn, and so the transit agency is trying to send enough trains that way. Officials see a Blue Line reduction as the only way right now, and since the Yellow Line bridge offers a relief valve, Metro can still give Blue Line riders just as many inbound trains each day, but some riders who used to have a direct trip may find themselves making a transfer.

The only way to resolve this capacity crunch is, in the short term, for local governments to fund more railcars and more power stations, and eventually build another Potomac crossing. Without a new river crossing, there can't be more trains on Blue, Orange, and Silver at the same time.


Three ways Metro's loop proposal could get better

Metro's proposed loop has generated much discussion about the future of the transit system. While new capacity is an important goal, it's not the only goal. Metro should also try to avoid designing in problems. A few tweaks could greatly improve the proposal.

Gallery Place crowding. Photo by the author.

One of the challenges of adding in a new crosstown line where one was never envisioned is dealing with transfers.

It's absolutely essential that Metro get these transfer stations right. Today, Gallery Place is a nightmare due to its flawed design. That station was designed with two major flaws. The off-center meeting of the Green and Red Lines is due to the Red Line swinging south to Judiciary Square. The narrow platforms are because of the historic art museum upstairs. We're still paying for a design decision made 40 years ago, and it really illustrates the need to get it right this time.

Metro's loop proposal is still very nebulous because it's so early in planning. Much could change. But the conceptual alignments shown in their map suggest the potential for inefficient transfer stations.

Building better transfer stations

At Waterfront, for example, the Green Line follows M Street. The proposed loop would run under Eye Street, 3 blocks north. Right now, riders from Alexandria and South Arlington have a straight shot on the Yellow Line to the 7th Street subway and the eastern side of downtown.

See the Waterfront station under: Eye Street M Street. All graphics by the author.

If the new loop station is built at 4th and Eye, those riders will have to walk over 1,000 feet to change from the Yellow to the Green. That's as long as the walk from Metro Center to Gallery Place. The additional inconvenience and time it takes to transfer will make transit less competitive for many riders. And it may create future crowding issues, like those faced at Gallery Place.

Locating the new station adjacent to the existing Waterfront stop would make transferring much easier and less time-consuming. And that would be a boon for many riders, especially those who would need to transfer under the new scheme, like anyone who takes the current Yellow Line from Virginia to downtown DC.

There's an even better solution than just building the new station next to the old one: Build a new station for the Green Line and the loop line.

A four-track design like the one above would make transferring very easy. Many riders wouldn't even need to use an escalator. Inbound trains would be on one level and outbound trains would be on another. This is exactly like the design of the Lionel-Groulx transfer station in Montreal.

This would probably not be possible as a reconstruction of the existing Waterfront station, but would probably need to be new construction adjacent to the current stop.

In this design, a commuter riding from Suitland to Union Station could simply exit her Green Line train at Waterfront and walk across the platform to board a Loop train on the outer loop headed toward Capitol South and Union Station.

Similarly, a person commuting from Huntington to Archives could get off his Yellow Line train at Waterfront and just walk right across the platform to a waiting Green Line train headed toward L'Enfant and Gallery Place.

Similar situations exist where the proposed loop line crosses the Red Line. Metro's proposal seems to keep the new line under H Street near Union Station and under M Street where it crosses Connecticut Avenue.

The Red Line is currently Metro's busiest line, and it provides access to many destinations. Forcing riders to make long walks is inefficient, and if the tunnels deposit riders at one end of the platform, a situation similar to the one at Gallery Place is likely to arise again.

The transfer at Farragut North/Longfellow isn't as bad as the potential one at Waterfront. But the walk between the stops would still be almost 750 feet. Instead of keeping the line under M Street, the loop could swing down Vermont Avenue to either K or L Street. That would allow a much shorter transfer between the Red Line and the Orange Line as well.

See the Farragut station under: M Street K Street

At Union Station, Amtrak has grand plans to expand the station and create a second front along H Street on the north side of the complex. In that regard, Metro's loop wouldn't be too inconvenient to commuter and Amtrak trains. Of course, if the redevelopment of the station doesn't happen, riders would have a less pleasant trek to connect to their trains.

But the walk to connect to the congested north end of the Red Line platform is over 600 feet. And that means that riders connecting to trains bound for Metro Center or Silver Spring would also have an inconvenient transfer.

Locating the new loop station on the south side of the station, under Massachusetts Avenue, could make transfers much easier, and it wouldn't sacrifice access to commuter or Amtrak trains either.

See the Union Station station under: H Street Massachusetts Avenue

The Massachusetts Avenue alternative also seems to make it easier to extend the M Street subway east across Capitol Hill and/or the 2nd Street subway up North Capitol Street should future demand warrant that expansion. Ideally, the station under Massachusetts Avenue would include 4 tracks and 2 platforms so that if the loop were split into an east-west and a north-south line trains wouldn't have to share tracks.


One of the bigger tradeoffs is the discussion of whether increasing the area within a 5 or 10 minute walk of transit is more important than easy transfers.

For example, if the new loop line is pulled down to K Street at Farragut Square, the West End station would be farther south, closer to the existing Foggy Bottom station. That means that less new territory would be within a 5 minute walk of Metro. On the other hand, essentially all of the West End is already within a 10 minute walk of Metro.

Compare some alternatives below. Note that the tan and gray areas are within 10 and 5 minute walks of existing stations. Light pink areas would be new areas within 10 minutes of Metro and dark pink areas would be new areas within 5 minutes of Metro.

Walksheds from existing stations.

Walksheds from Metro's loop proposal.

Walksheds from a K Street/Mass Ave alternative.

Better transfer stations could mean fewer headaches for future commuters. But it might also mean less area is available for new development in the core, lowering tax revenues for the District. Co-locating stations is also likely to be more expensive and disruptive to riders. But in many cases, it may well be worth it. It's certainly worth having the discussion.


How would Metro's loop work with an Arlington express line?

Last week, we discussed Metro's proposed new downtown loop line in terms of the Blue and Yellow lines. Metro also plans to feed the loop with a new "express" line along I-66 in Arlington.

While Metro's plans are still in the early stages, at the moment, they seem to be focusing on a new line that would follow I-66 between East Falls Church and Rosslyn, bypassing the crowded Rosslyn-Ballston corridor.

All graphics by the author.

Metro's 2040 projections indicate the need for a new line in Northern Virginia. They estimate that by 2040, there will be significant crowding aboard inbound Silver Line trains before they even get to Tysons, but sharing track with the Orange Line constrains its capacity. They also estimate that by 2040, passengers in the Rosslyn-Ballston Corridor will find it difficult to board trains, with crowding conditions beyond what is considered acceptable today.

The new express corridor would run alongside the Orange Line in the median of I-66 from the junction with the Dulles Airport Access Road until the Orange Line splits off to follow Fairfax Drive. The new line would stay in the median of I-66 to bypass the Rosslyn-Ballston corridor.

The new line would allow up to 26 trains per hour (TPH) to run on the Silver Line as well as on the Orange Line, for a total of 52 TPH passing through East Falls Church. It would feed the proposed downtown Metro loop, along with the Blue and Yellow Lines.

The map above shows one way the new line could operate. Under this scenario, the Silver Line would have a companion, which I'm dubbing the Gold Line for the purposes of this discussion.

The downtown loop would have a capacity of 26 TPH in each direction. The Blue and Yellow lines would use 13 TPH of that capacity in each direction, leaving 13 TPH available on the inner loop and 13 TPH available on the outer loop. For this reason, half of the trains on what I'm calling the North Arlington Express line would need to run counterclockwise and half would need to run clockwise, at least to use the loop to its full capacity.

To avoid confusion, it is likely that Metro would use two different colors for the express line. In the scenario outlined in the map above, half of the trains coming from Dulles would be colored Silver, while the other half would be Gold. Each would alternate, going around the loop in the opposite direction.

Of course, it would also be possible to "transform" the lines as I described with regard to the Blue and Yellow lines on the loop in the last post. That way, riders would be used to taking the same color in the morning as the evening. But I did not illustrate that in a map, because with four lines on the loop, it becomes increasingly complex to show the transforms.

Running trains from the North Arlington Express onto the loop would maximize the capacity of the Dulles/Tysons line, the Orange Line, and the loop line at 26 TPH each.

Metro is not wedded to running the line down I-66. As planning continues, WMATA will do studies to determine the best location for the new line. It could be along I-66, or it could follow another corridor, but the concept is the same. By separating the Silver and Orange lines, WMATA can increase capacity to match the expected demand in northern Virginia.


How might the new Metro loop work?

Last week, WMATA planners released a proposal for a new Metro loop downtown to help relieve capacity issues on the other lines. How might this new line operate? Details are scarce, but we can talk about some possibilities.

Map from WMATA.

The proposal is to build a new Metro line that would loop through downtown DC. Starting at Rosslyn, the tracks would tunnel under the Potomac to Georgetown. They would then follow M Street and New Jersey Avenue to Union Station. The tracks would turn south along 2nd Street to cross Capitol Hill, and then parallel the Green Line under I Street. The loop would complete itself by joining to the existing Yellow Line bridge over the Potomac River.

Metro's proposal indicates that the loop line will be fed by the current Blue and Yellow lines, which would enter at the Pentagon station, and a new "express" line in northern Arlington, which would enter near Rosslyn.

Why build a loop?

Metro's team of planners looked at a variety of solutions to the core capacity issues, including new lines. The alternative they settled on was this loop. Why did they pick a loop?

Essentially, a loop solves most of Metro's problems relatively cheaply. The primary issue facing Metro over the next few decades is core capacity, espcially in terms of train throughput. The Blue/Orange subway through downtown is at capacity, and no more trains can be added.

Untangling the Gordian knot at Rosslyn is the most complicated part of this. What is most clear is that Metro needs a new Potomac crossing near Rosslyn to increase capacity on the Blue, Orange, and Silver lines.

But Metro also needs more capacity around the southern side of downtown DC. Because the Green and Yellow Lines share the 7th Street subway, which is operating very close to capacity, each line can only be increased at the expense of the other line. In other words, WMATA can't add Green trains without subtracting Yellow trains. So Metro also needs a new subway for the Yellow Line.

However, Metro's studies found little need for a new subways outside of downtown based on the expected travel patterns in and density of those areas in 2040.

Essentially, Metro sees the need to build an east-west subway across the north side of downtown and a north-south subway across the east side of downtown. But they don't see a need for the east-west subway to continue east or the north-south subway to continue north.

For that reason, Metro thinks it makes the most sense to just connect the east-west and north-south subways at Union Station and operate them as a loop.

Operating patterns

It's not exactly clear how the new subway loop would work, and since this project is decades away from completion much could change. But there are a few likely ways it could operate.

For now, let's only consider the Blue and Yellow Lines. We will discuss the proposed North Arlington Express line in a later post.

Operating an inner and outer loop is one of the obvious choices. In this scenario, one of the lines would run clockwise around the inner loop, while the other line runs counterclockwise around the outer loop.

Scenario 1. All maps by the author unless noted.

So Yellow Line trains coming from Huntington would cross the Potomac north of the Pentagon, as they do today. Then they would continue east to Capitol Hill before turning north toward Union Station and going around the loop to return to Huntington via Arlington Cemetery. Blue Line trains would do the reverse.

One of the advantages of operating the Yellow and Blue lines as a loop through downtown is that the loop can actually carry more capacity. If the Blue and Yellow didn't need to share tracks with the Orange and Green lines, each could run at a frequency of 13 trains per hour (TPH) in each direction. And that means that the outer loop would have 13 TPH, as would the inner loop. Since Metro's track capacity is 26 TPH, there's actually room to add two more lines to the loop.

One of the disadvantages, though, is that riders who have a short one-seat ride in the morning have a long one-seat ride in the afternoon. Someone who commutes from Franconia to Georgetown has a pretty direct trip in the morning. But in the afternoon, they either have to face a long ride on the Blue Line via Union Station and Potomac Park or take a two-seat ride by riding the Yellow Line to Pentagon and changing.

"Transforming" loop trains would resolve that problem, though it would be more complicated and difficult to show on the map.

Scenario 2.

In this scenario, a Blue Line train leaving Franconia would run as far as Pentagon and then continue toward Arlington Cemetery. At some point on its journey, the train would magically transform into a Yellow Line train bound for Huntington. Yellow Line trains would operate similarly, becoming Blue Line trains during their journeys.

This way, a person who commutes from Franconia to Georgetown would have a short, one-seat ride on the Blue Line in both directions. The same would be the case for Yellow Line riders.

For anyone waiting for trains at a station on the loop, trains on the outer loop would always be bound for Franconia, but would have come from Huntington. On the inner loop, trains would be bound for Huntington, but would have come from Franconia.

To avoid confusion, trains bound for the loop would just be signed with their color and a destination of "Downtown." The change of color and destination on the loop wouldn't matter for the passengers on board, since the train would continue around the loop. This is, incidentally, what Chicago L trains do as they arrive at the Loop: they change their headsigns from "Loop" to whichever destination they're headed back to.

Alternatively, trains don't have to "loop" all the way around the loop. Instead, the Blue and Yellow lines could just be interlined on the new tracks.

Scenario 3.

In this scenario, Blue Line trains would operate onto the new tracks for a certain distance. On the map above, I've shown trains going as far as 4th & Eye, but they could stop at any point along the line (Union Station, for example). Then trains turn back around and run over the same tracks back to Franconia. Yellow Line trains would operate similarly.

Anywhere the two lines overlap would max out the capacity of the new line, just as the other lines in the core are currently topped out at 26 TPH. The reason this is true for the interlined scenario but not for the loop scenarios is because in the loop scenarios, trains run around the loop once. In the interlined scenario trains run over the tracks twice, once inbound and once again outbound.

North Arlington Express trains

As noted above, the new loop would also carry trains from the North Arlington Express line. We haven't discussed those trains yet, but we're going to cover how they might work with the loop in another post soon.

Metro's vision for the future is still decades away, so we have no idea what the final product will look like exactly. It might look like one of the operating patterns shown here, but then again, lots can change in 25 years. But Metro's core is approaching capacity, and expansion is desperately needed. Metro's new vision will set the stage for building the system's next generation.


Metro maps out loop line between DC and Arlington

To relieve congestion on the Orange and Blue lines and support future growth in the region's core, Metro is proposing a loop line between downtown DC and Arlington. They've just created a map of what the service might look like.

Detail of Metro's proposed downtown loop from PlanItMetro.

The loop is part of Metro's Regional Transit System Plan, which lays out a vision of how the transit system should expand over the next three decades to accommodate predicted regional growth. It incorporates previously studied ways to expand Metro in downtown DC, including new Blue and Yellow lines.

The loop line would go to areas that don't have Metro service, like Georgetown, while adding new connections to existing transfer points like Farragut Square and Union Station. It's unclear how Metro's service patterns would change to serve the loop. Right now, the map shows the Blue, Orange, Silver, and Yellow lines all running on the loop.

WMATA planners are also considering an express line on I-66.

Metro's also looking at a new express line along I-66 between Rosslyn and East Falls Church, which could give the Silver Line an alternate, faster path to downtown DC. This isn't a new idea, either.

What do you think of Metro's loop line?


Metro beyond 2025, part 2: The Blue Line to Georgetown

Yesterday, we discussed how Metro could grow its core capacity if it chooses to build a Rosslyn wye in the short run. Today we'll look at how a terminal for the Blue Line could fit into the picture.

Photo by tracktwentynine on Flickr.

Today, Rosslyn is the biggest bottleneck in the system, which will only get worse when the Silver Line opens. Three lines vie for space in one tunnel from Rosslyn eastward, which limits trains on the Blue, Orange, and Silver Lines.

Metro could relieve the pressure for now by either building a new terminal for the Blue Line at Rosslyn, or a "wye" to let some trains from Tysons go to Arlington Cemetery and farther south in Virginia. But in the long run, Metro needs more capacity over the Potomac River.

Post-2025 solutions with a Rosslyn terminal

The Rosslyn terminal would enable Blue Line trains to terminate at Rosslyn without interfering with the Orange or Silver Lines. This would allow more Orange and Silver trains from Tysons and the Rosslyn-Ballston corridor. But it also means that all Blue Line riders going to DC would need to transfer at Rosslyn or Pentagon.

That solution might work for a few years, but if Metro ridership continues to grow, the Rosslyn terminal would need to become the first phase of a new Potomac crossing.

A separated Blue Line: Metro could easily expand a Rosslyn Terminal into a new line to DC. A likely path would take the line under the river to Georgetown and then east into the downtown core.

In addition to the 26 trains per hour (TPH) running between Rosslyn and Downtown on the Orange/Silver subway, an a separated Blue Line to Georgetown and into downtown would allow 12-16 additional trains to cross the Potomac at Rosslyn.

This would increase the number of trains running between Virginia and DC per hour during the peak from 40 to 52.

However, because the Blue Line shares with the Yellow Line, the new subway across downtown Washington would only be able to operate at roughly half of its maximum capacity. That's probably fine in terms of ridership for a while (and off-peak for much longer), but in order to get the full potential out of the new line, it would need to be separated from the Yellow Line.

A separated Blue Line could also allow for more service on the Green Line through the Waterfront or Capitol Riverfront areas, which are quickly adding jobs. Metro could get some additional Green capacity by shifting some Huntington trains to the new Blue subway via Rosslyn (a sort of reverse Rush Plus).

Shifting some Huntington trains to run through Rosslyn would not increase the number of trains crossing the Potomac beyond what could cross under the first separated Blue Line scenario, but it would enable more service on the Green Line.

Two new subways?

What about both a separated Blue Line and a separated Yellow Line? Two new subways in the core would be very expensive. But if Metro wants to maximize the capacity on its system, it has to separate each line in the core.

One way to do this is to build a new terminal for the Blue Line at Pentagon. The Blue Line could have its own platforms, and trains from Franconia-Springfield (now all colored Yellow, or perhaps a new color) and Huntington would all cross the 14th Street bridge.

This would also have the advantage of reducing the amount of interlining in the system. With the lines no longer sharing with each other, delays wouldn't cascade across multiple lines if a train were to break down or some other mishap were to occur.

But the real issue is being able to have the flexibility to balance trains across the different lines. Right now, the Blue and Orange must be balanced based on ridership demand, as do the Green and Yellow. The problem is that Metro is bumping up against the absolute capacity of both subways.

With just a separated Blue, there would still be demand for a direct trip across the 14th Street Bridge. And once that demand outstrips Metro's ability to provide supply, Metro won't be able to do anything (because the Yellow shares with the Green). With just a separated Yellow, service between Pentagon and the western side of downtown is constrained by demand for the Orange/Silver.

At some point in the future, if Metro keeps growing, it may become necessary to build the other separated line. With both a separated Blue and a separated Yellow, the number of trains crossing the Potomac would increase to a maximum of 78.

Other improvements would probably be necessary to enable a full 26 trains per hour to run on the Green Line. It's not clear if the terminals at the end of each line could handle turning 26 trains each hour. Metro would probably need places for trains to turn around short of the terminals, like the pocket tracks at Silver Spring and Grosvenor on the Red Line. Alternatively, Metro could look into rebuilding the terminals, Branch Avenue and Greenbelt, with more capacity.

It's hard enough to say if we can get one new subway by 2040, given the funding picture today. But a second new subway might be in the cards farther down the line, and now is the time to start planning for it.


Metro beyond 2025: Possible futures with new connections

Last week, we talked about plans to give Metro the capacity it needs to get through 2025. What about beyond? The primary issue after 2025 will be cross-Potomac capacity.

Photo by the author.

Metro will likely choose to build, hopefully by 2025, either a new terminal for the Blue Line at Rosslyn that doesn't share tracks with the Orange or Silver Lines, or a "wye" so trains from Vienna and Tysons can turn toward the Pentagon.

However, neither solution increases the number of trains that can cross the Potomac River. Metro will need to start planning for the next phase very soon, since it takes so long to plan and build transit. Also, Metro's plan beyond 2025 could influence which of the options (terminal or wye) it chooses for 2025. Let's look at how Metro might expand its core capacity starting with each of the 2 primary Rosslyn alternatives.

Post-2025 solutions that go with a Rosslyn wye

Without construction in the core, a Rosslyn wye alone can't add any cross-Potomac capacity. Metro could build a second wye at Pentagon, for trains from Vienna and Tysons to cross the 14th Street bridge. However, the 7th Street tunnel, which carries the Green and Yellow Lines through downtown, can't take any more trains.

Wyes at Pentagon and L'Enfant: If Metro builds a total of 3 wyes, at Rosslyn, Pentagon, and L'Enfant Plaza, it could fit a few more trains across the river. Trains from Arlington Cemetery could cross the 14th Street Bridge, then continue east onto the Green Line toward Branch Avenue.

This scenario would let Metro fill unused capacity in the system without building any new trunk lines. However, much of this new capacity would go on the Green Line south of Waterfront station. Customers wanting to get to the downtown area would have to transfer.

It would, however, significantly add service to the growing Waterfront and Capitol Riverfront areas. DC has zoned much of these areas for downtown densities, but instead of the 5 lines that serve downtown or 3 in the Golden Triangle, this area has just one. This option would beef up service there, though many of the people riding there would want to come from downtown, and this doesn't boost that connection.

To absolutely max out capacity, Metro would need to run a line, like the lime-colored line on the map above, from Franconia to Branch Avenue. It's not completely necessary, but it would allow more full use of the capacity.

Unfortunately, this would increase the amount of interlining in the system, because trains would be running across multiple lines. The complex scheduling it would take to run this sort of service pattern might actually lower the total number of trains Metro can run through a tunnel.

This scenario would increase trans-Potomac capacity from 40 to 52 trains per hour, or just to 46 TPH without the Franconia-Branch Avenue Line.

Pentagon wye and separate Yellow Line: Metro has talked about building a separate tunnel for the Yellow Line. It's not clear where it would go yet. It could run north along 9th or 10th Street, or it could run east toward Capitol Hill before turning north.

This subway would separate the Yellow and Green Lines. That would allow Metro to run additional Green Line service between Greenbelt and Branch Avenue, including more service between downtown and the Waterfront/Riverfront areas.

It would also allow more service across the Potomac by decoupling the Green and Yellow Lines. However, since the Yellow Line shares tracks with the Blue south of Pentagon, this new subway would not be used to its full capacity.

Metro could get some additional capacity by routing some trains from Tysons via Arlington Cemetery over the 14th Street Bridge and into the new subway, if it built a wye at Pentagon. This would increase service across the Potomac to 52 TPH. Without the line running from Tysons through Arlington Cemetery, that would drop to 46 TPH.

Splitting Yellow Line service: Another option Metro studied for the Yellow Line is a new tunnel through the Capitol Riverfront, past the Capitol, and north to Union Station. This would increase service at Union Station, a major bottleneck, and give riders two ways to get downtown from the Waterfront/Riverfront area.

However, a lot of the riders in Alexandria and southern Arlington don't want their train to go so far east. They want to get to the 7th Street corridor. Therefore, Metro studied the idea of splitting the Yellow Line, with some trains taking their current path through L'Enfant Plaza and Archives while others would go to Union Station.

This operating plan makes a lot of sense with the Rosslyn wye, because those trains can fill the "gap" left on the 14th Street Bridge by Blue Line trains running north toward Rosslyn. With a new path for some Yellow trains, there would be room to add more Green Line service.

This approach would allow 52 trains per hour to cross the Potomac.

Tomorrow, we'll look at another set of long-term solutions, which Metro might pursue if it builds a new Blue Line terminal and then can send the Blue Line across the river toward Georgetown.

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