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Ask GGW: Why do some stations have side platforms?

Have you ever wondered why your Metro station has two side platforms instead of a single island platform? If so, you're not alone. Reader Sam Inman is curious, too.


Images by the author.
Why are some stations (I'm particularly interested in the subterranean stations) designed with the side platform design instead of the island?

Do you know if this is dictated by a topography/cost concerns? Or was there a design consideration that wanted to force passengers to make their decision at the mezzanine level rather than on the platform level?

Unfortunately, the answer is not simple. In practice, the layout can be influenced by a variety of factors, so there's great variation between transit systems. But there are some general rules that influence the layout (though they're not hard and fast).

Economics
In general, island platforms can be cheaper because they require less duplicative infrastructure. However, sometimes other technical factors can make side platform stations cheaper.

With an island platform, the station requires less vertical circulation. For example, Foggy Bottom only needs 1 mezzanine-to-platform elevator, since it has an island platform. But Farragut West needs 2 mezzanine-to-platform elevators, since it has side platforms. Staircases and escalators can do double duty at an island platform, but sometimes need to be duplicated at side platform stations.

Loading can also be an issue. For example, at a station that is very commuter heavy in the morning with passengers all traveling the same direction, a side platform station may have one platform that is very full and one that is completely empty. That's less efficient than an island platform, where the passengers can use the whole platform, even though they're primarily focused on one track.

But oftentimes these considerations take a back seat to the method of construction, which can also influence the station design.

Construction influences
For underground construction, if the line is cut-and-cover, it is often more cost-effective to build side platforms. With cut-and-cover construction, the tunnels are constructed by digging up the street, building the tunnels, and then rebuilding the street.

To build an island platform station with this method, it requires the two tracks be spread apart from each other (to give room for the platform). This requires more excavation than a side-platform station, which only requires the extra width for the length of the station.


The difference in excavation required for side versus island platforms. Graphic by the author.

So when subways are constructed using cut-and-cover, like along I Street around McPherson and Farragut Squares, stations often have side platforms.

On the other hand, when a subway line is deeper, and is bored through the ground, it often makes much more sense to have island platform stations. This is because when lines are bored, the two subway tubes are not directly next to each other. Since the tracks are already apart, when they get to a station, it's much easier to just put the platform between the tracks, rather than to pull the tracks together so the platforms can be on the outside.

This is the case for the deep stations along Connecticut Avenue and Wisconsin Avenue between Woodley Park and Medical Center.

It's much rarer, but sometimes both tracks are built in the same (larger) subway tube. This is the case for the Red Line between Farragut North and Woodley Park (not including either of those stations). Both tracks are in the same (bored) tunnel, and so at Dupont Circle, it makes much more sense to have side platforms, since the tracks are already right next to each other.

This is also the case for almost the entire Montreal Metro system, where the tracks are always in the same tunnel. As a result, almost every station has side platforms.

There's less pressure for one or the other design on elevated and surface rail lines, since the construction is cheaper than subway construction. However, there are still some influencing factors. For example, when the tracks are running in a freeway median, the road lanes have to spread out in advance of the station anyway, so there's no penalty for spreading the tracks out ahead of time either. So in that case, there's no penalty for an island platform station. For a side-platform station, the only penalty is the duplicated infrastructure.

On an elevated viaduct, it might be easier to have one structure carrying both tracks rather than two separate structures for each track, and therefore side platform stations may be cheaper, like at West Hyattsville. But then again, it's not necessarily better one way or the other, and so sometimes an island platform makes more sense, like at McLean.

Design decisions
Sometimes, though, a transit agency might make an intentional decision that overrides other concerns.

Terminal stations should have island platforms so that the next train can leave from either track. So any station that is planned to be a terminal for any period of time generally has an island platform. When a terminal does have side platforms, generally trains have to go out of service on one platform, go past the station, reverse, and then pull in on the other platform. That's very inefficient. Alternatively, passengers have to wait in the mezzanine and then pick a platform when the train is ready to depart, also inefficient. All of Metro's terminals have island platforms.

Any station that is likely to be a transfer between diverging lines should have an island platform. That way a passenger coming from one branch can transfer to the other branch simply by walking across the platform. This is the case at Stadium/Armory, where a passenger riding from Addison Road to New Carrollton can make an easy cross-platform transfer.

Furthermore, at key stations, certain platform arrangements can be more efficient.

Metro Center, Gallery Place, and L'Enfant Plaza are good examples. With right-side exits on the upper level, there can be multiple escalator shafts down to the island platform on the lower level. If both levels at these stations had center platforms, the only efficient layout would be to have a mezzanine between, which is how Fort Totten is laid out. And that's generally more expensive and less efficient. Though in the case of Fort Totten it works because the lines have such a great vertical separation (the Red is elevated, the Green is underground).

Other design factors
And while we don't have any examples of it in the Washington region, the "Spanish solution" can also be employed to reduce dwell times. The Spanish solution is where the doors on both sides of the train open. This makes it faster to unload and load the train. MARTA's Five Points station has this on both the upper and lower levels.

When looking at express/local configurations, having island platforms between the local and express tracks allow for an easy cross-platform transfer between trains going the same direction. But at some stations where express service needs to stop, but where the agency wants to discourage transferring passengers (because of crowding), the island platform can be placed between the two express tracks and with the local tracks having side platforms. This is the case at 34th Street/Penn Station on the 1-2-3 and A-C-E. That station is important enough that all trains need to stop, but the stations are crowded. The traditional island/island layout is present one stop north at Times Square/42nd Street to allow transfers between locals and expresses.


Graphic by the author.

In systems that have express/local tracks, there are even alternate ways to accommodate local stations. In New York, local tracks tend to be on the outside, so local-only stations have side platforms. The drawback here is that if the local service ends before the express service, it's difficult to turn those trains around, since they have to cross over the express tracks. The Lexington Avenue (4-5-6) Line handles this by having the local 6 train dive under the 4-5 express tracks via the City Hall Loop.

A rarer alternate version is to put the local tracks in the center. In this case, with the express tracks on the outside, the local-only stations have center platforms. This is present on Chicago's north side trunk, with the local Red Line in the center and the Purple Line Express running on the outer tracks.

So, as you can see, the logic is somewhat complicated. Sometimes it's cheaper to do one, sometimes it's cheaper to do the other. Sometimes, there are logistical reasons for doing one over the other. Sometimes, it may just be more-or-less random.

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 Planning Department. His views are his own and do not represent the opinion of his employer. 

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If both levels at these stations had center platforms, the only efficient layout would be to have a mezzanine between, which is how Fort Totten is laid out. And that's generally more expensive and less efficient. Though in the case of Fort Totten it works because the lines have such a great vertical separation (the Red is elevated, the Green is underground).

Define "works." Transferring at Fort Totten is terrible precisely because of the need to make two level changes (because of the mezzanine on the middle level).

by TimK65 on Aug 22, 2014 11:30 am • linkreport

Define "works." Transferring at Fort Totten is terrible precisely because of the need to make two level changes (because of the mezzanine on the middle level).

and because one must walk to the far north end of the green line to access the stairs/escalators.

Both Green/Red interchanges are terrible.

by Richard on Aug 22, 2014 12:03 pm • linkreport

@TimK65 - I think what Matt means here is that Fort Totten "works" because the Red is already elevated and the Green is already sunken when both enter and leave the station... so it "makes sense" to have the entry mezzanine on ground level inbetween. If you stop and think about it, the only other configurations possible there would be either:
(1) have the Red Line dip underground too for just Fort Totten OR
(2) have the Green Line soar up in the air again for just Fort Totten.
Either of those options would have kept the Red and Green platforms only 1 level apart... but would also have dramatically increased construction costs for such a big difference in decline/incline of either line's tracks.

by Dave on Aug 22, 2014 12:07 pm • linkreport

Thanks Matt! A really complicated but interesting answer.
-Sam

by Sam Inman on Aug 22, 2014 12:08 pm • linkreport

@TimK65:
When I said "works" with regard to Fort Totten, I mean that it was technically feasible. I transfer here twice daily, and I agree that the station would be better if there were just one level change between the Red and the Green.

But if WMATA had designed it so the Red had side platforms and the Green had an island platform, with direct escalators between them, they would have needed to be very long escalators stretching, probably, to the very ends of the Green Line platform due to the vertical separation between the lines.

by Matt' Johnson on Aug 22, 2014 12:08 pm • linkreport

I guess there was a 3rd option... have the Red operate on ground level and raise EVERYTHING ELSE around Fort Totten so that the entry would occur on an elevated mezzanine... that would've also preserved Green-to-Red at 1 level apart... but would've been very awkward for Fort Totten-area customers to use (go upstairs to go back downstairs again).

(Try walking into Tysons Corner where the faregate mezzanine is above the tracks which are above the street for an example of how awkward this is.)

by Dave on Aug 22, 2014 12:11 pm • linkreport

But if WMATA had designed it so the Red had side platforms and the Green had an island platform, with direct escalators between them, they would have needed to be very long escalators stretching, probably, to the very ends of the Green Line platform due to the vertical separation between the lines.

Given the constraints from the freight rail tracks, I don't know that side platforms would've been feasible for the Red Line; a direct connection to the Green Line tracks would not only be a long escalator ride, but it would also have to run perpendicular to the RD tracks, meaning that the freight tracks would have to deviate substantially from their current location.

Also, the middle 'transfer' level is where the street-level entrance faregates are. If you removed that level, you'd face a challenge in getting passengers coming in from the street to either platform.

Given those constraints, it's not hard to see why they ended up with the existing configuration. What I think the station could really use would be additional vertical circulation between the GR platform and the mezzanine.

by Alex B. on Aug 22, 2014 12:23 pm • linkreport

I had previously never heard of the "Spanish Solution". I always thought of that as " roller coaster configuration" with entry on one side and exit the other.

by spookiness on Aug 22, 2014 12:25 pm • linkreport

Given the constraints from the freight rail tracks, I don't know that side platforms would've been feasible for the Red Line; a direct connection to the Green Line tracks would not only be a long escalator ride, but it would also have to run perpendicular to the RD tracks, meaning that the freight tracks would have to deviate substantially from their current location.

The freight tracks could have been in the center....

by Richard on Aug 22, 2014 12:26 pm • linkreport

@Richard:
Yes, the freight tracks could have been in the center, but remember, terminals need to have island platforms (at at a minimum, the tracks need to be able to connect for crossovers at the terminal and periodically in between).

And that would mean that the Red Line tracks would need flyover tracks on either side of Fort Totten (over the freight tracks), and that would have significantly increased the cost.

There are no hard-and-fast rules. Agencies designing stations look at a variety of factors, and one of them is keeping the cost of particular designs within a reasonable range.

Yes. There are probably better ways of designing transfer stations than Fort Totten. But given the context of that particular station, it would have been (1) more technically challenging, (2) operationally challenging, and (3) more expensive to do a different design.

And let's not forget that NPS was involved, since they own the park. We're lucky they let WMATA build a station there in the first place. I mean look at Farragut Square. I mean Farragut North and Farragut West, which they prevented from being one station, like Metro Center.

Would it have been worth it to do Fort Totten differently? I don't know. But it's water under the bridge now.

by Matt' Johnson on Aug 22, 2014 12:32 pm • linkreport

Fascinating! Thanks for sharing this knowledge. As for the 34th Street station in NYC, I find it to be a terrible solution. If you're going to, say, 72nd street, you could take either the local or express. However, the station forces you to choose one or the other. As a result, many people simply wait in the undercrossing below. This has been improved by having real time train arrival info, but it's still annoying.

Another interesting thing happens at 145th St on the A/B/C/D. All trains operate on the same corridor, but the upper platform has the A/C trains and the lower platform has the B/D trains. As a result, people simply wait on the stairwell for the first train to arrive. Not ideal, but again real time information will improve this.

by TransitSnob on Aug 22, 2014 12:36 pm • linkreport

The freight tracks could have been in the center....

They could be in the center now, since they don't connect to anything. But they once did.

The freight tracks are on the outside so they could continue to serve rail spurs on both sides of the right of way. I don't think any such spurs are active now, but there were on both sides of the tracks at the time Metro was planned. Metro could've run along one side or the other (as the other branch of the Red Line does, as well as the Green line), but you may have needed additional flyovers to allow the freight sidings to have access to the mainline (such as the Orange Line between Landover and New Carrolton).

Also, putting the freight tracks in the center would mean that the Metro tracks couldn't crossover, which would make single tracking a much bigger pain than it is today.

by Alex B. on Aug 22, 2014 12:40 pm • linkreport

Really fascinating explanation for one of those "I wonder why . . . " questions that I've pondered but never thought deeply about. Great work!

by ah on Aug 22, 2014 1:24 pm • linkreport

There's at least one example of a side platform station with lots of non-subway tracks in the middle: Harrison on the PATH in New Jersey. No chance of a crossover there: http://nycsubway.org.s3.amazonaws.com/images/maps/pirmann-2003-path-track.gif

For the "Spanish solution", WMATA could do that if they wanted at National Airport or West Falls Church. It doesn't make much sense at WFC but at the airport I could see how it might be useful. (Of course the center track was used for many years as a terminal track for the Blue Line, before the Franconia-Springfield extension opened.)

by Andrew on Aug 22, 2014 1:28 pm • linkreport

This isn't the first time that someone has wondered about this:

http://unsuckdcmetro.blogspot.com/2012/01/dumb-and-dumber.html

by jms on Aug 22, 2014 1:32 pm • linkreport

Regarding Fort Totten:

There may have also been some lingering thought in Metro planning that the freight tracks would be removed and replaced with a freeway as of 1971. The website Roads to the Future offer a great resource to what could have been regarding the District's highway system. Image of the Fort Totten section at the second link.

http://www.roadstothefuture.com/DC_Interstate_Fwy.html

Image: http://www.roadstothefuture.com/DC_I95_FT_XL.jpg

Building the Red line any other way really wouldn't have worked.

by Randall M. on Aug 22, 2014 1:40 pm • linkreport

@Randall M.
That's an excellent point. However, I'll note that even if the freeway had been constructed, the B&O Railroad tracks would have been retained too. So in addition to the freeway, there still would have been 4 tracks.

You can see the B&O tracks in the graphic you shared.

by Matt' Johnson on Aug 22, 2014 1:48 pm • linkreport

The freight tracks are on the outside so they could continue to serve rail spurs on both sides of the right of way. I don't think any such spurs are active now, but there were on both sides of the tracks at the time Metro was planned.

I think there's only one spur still in use. There's a lumber business between New Hampshire and Kansas Ave that I've occasionally seen a rail car or two parked. It seems to be pretty rare though.

by Rob K on Aug 22, 2014 1:51 pm • linkreport

I really have no major complaints about Fort Totten. It isn't as crowded as Gallery Place, being suburban so it isn't so bad to transfer at.

The green line platform should be further East, so the stairs are not at one end of it but rather in the middle.

Obviously there should be a pocket track directly east of Ft. Totten on the green line.

Long term it would be great if there was more walkable space around the station, but that isn't really the metro station designers fault.

by Richard on Aug 22, 2014 1:52 pm • linkreport

@ Matt Johnson

You're right. I was attempting to support the idea that having side platforms on the red wouldn't be any better and more expensive. That said, the green line could have had side platforms as it narrows to a single tube under Fort Circle Park.

That said, although the idea of highways bisecting the District is a hideous idea, I like that they thought big back then. If only they thought big about subways...

by Randall M. on Aug 22, 2014 1:58 pm • linkreport

@Randall M.

Thanks for that link to the interstate plans. Fascinating to look at what could have been.

And while it may not seem like it, I kind of feel DC did think big with its subway system. From the design of the stations to the total size of the system, it was a pretty grand plan for what was a very carcentric city. And they actually did it - Metro was fully built more or less to plan, unlikely many other cities in the US that planned systems but then never committed to them.

by Mr. Johnson on Aug 22, 2014 3:11 pm • linkreport

Great post Matt.

That said, although the idea of highways bisecting the District is a hideous idea, I like that they thought big back then. If only they thought big about subways...

@Randall M: Totally agree on freeways through DC. You can make an argument that Metro being built in place of those freeways is a big part of the reason the city is so livable and prosperous today. I'd disagree on the not thinking big. Schrag's "Great Society Subway" details the numerous times that we came very close to building much less than the original 98 mile system. In every case, the full 98-mile (now 117-mile) system prevailed. We're actually pretty lucky to have what was built.

by Sherman on Aug 22, 2014 3:14 pm • linkreport

And while it may not seem like it, I kind of feel DC did think big with its subway system. From the design of the stations to the total size of the system, it was a pretty grand plan for what was a very carcentric city. And they actually did it - Metro was fully built more or less to plan, unlikely many other cities in the US that planned systems but then never committed to them.

I don't know how anyone could possibly say that DC didn't think big with the Metro. Look at how most places are building transit today- little streetcars or light rail, one little line at a time, expanded piecemeal with no planning for a big, comprehensive map. In DC, they planned out a giant, largely underground heavy rail system from day one, and over a few decades, they built it, with only minor modifications. They planned it well enough that it became second only to New York's subway, and a key component of DC infrastructure. Even for people who don't use the metro much, at this point, the city would be unimaginable without it. The planners intended nothing less than to radically transform how people traveled in DC. They knew it would take decades to build, but they thought big and created a system that, despite its flaws, is one of the better subway systems in the world.

Sometimes you have to step back and take a moment to appreciate what you have. The Metro was not inevitable. The people designing it dreamed big and made it happen.

by Zeus on Aug 22, 2014 3:59 pm • linkreport

@Randall M: Totally agree on freeways through DC. You can make an argument that Metro being built in place of those freeways is a big part of the reason the city is so livable and prosperous today. I'd disagree on the not thinking big. Schrag's "Great Society Subway" details the numerous times that we came very close to building much less than the original 98 mile system. In every case, the full 98-mile (now 117-mile) system prevailed. We're actually pretty lucky to have what was built.

I think he was lamenting that today especially we are not planning anything big. We are building dinky street cars and light rails, but where is the next 100 mile system in the US?

by Richard on Aug 22, 2014 4:27 pm • linkreport

wrt Fort Totten, not sure when MARC service would have stopped serving Takoma Station. Service was provided into the 1970s. That was likely an element too.

Years ago I wrote a piece in response to some Brooklanders agitating for "decking" over the Metro saying that undergrounding the railroad would have had to have been planned in association with the building of the Metro system, for something like that to make sense.

http://urbanplacesandspaces.blogspot.com/2007/07/rethinking-metropolitan-branch-railroad.html

In any case, the amount of land produced by undergrounding the Metropolitan Branch wouldn't have justified the cost, because the width of the tracks is relatively minimal.

by Richard Layman on Aug 22, 2014 4:30 pm • linkreport

@Richard:
where is the next 100 mile system in the US?
Los Angeles.

by Matt' Johnson on Aug 22, 2014 4:30 pm • linkreport

I don't mind the good light rail systems in the Western US- Salt Lake, Denver, not to mention Portland have good ones- but yeah, I sometimes wonder if any city here could get the funds and government will to build a heavy-rail subway ever again.

by FBJ on Aug 22, 2014 4:45 pm • linkreport

Agreed with some others that Randall was referring to today's state of affairs: piddling streetcars and small-minded ad hoc improvements.

Matt, I'd agree that LA is probably the biggest thinker in the US now, but even that - for a city of that density and scale - doesn't go nearly far enough.

For our purposes here in DC, I'd ask: where's the next 100-mile system plan? Where's our "second system?" (In the sense of big plans, not of plans that get shelved for a century.)

by Low Headways on Aug 22, 2014 4:50 pm • linkreport

@Et. Al and @Richard

Yes, Metro is large, especially considering when it was built (when cars were truly king). That said, the concept of a two-track system always seemed to me to be a narrow vision compared to what we do for the 8 or more highways lanes that we see around the beltway. I read the Great Society Subway and I know the dynamics of the time which saw the hollowing out of the core. Still, two crossings into VA never seemed to be enough, even then.

Today, we fret over putting Metro underground in Tysons or Dulles, street cars, dedicated transit lanes - it's amazing that we get anything built. Looking at the highway plans then, the scale and costs would be massive, we almost never do anything like this.

I just wish we built like this for transit.

by Randall M. on Aug 22, 2014 5:07 pm • linkreport

Sometimes it almost makes one wish for a China-like dictatorship to build Shanghai Metro-sized networks under every urban center in the next ten years.

Then, you know, you remember that people generally value human rights over transit systems. But still.

by FBJ on Aug 22, 2014 5:10 pm • linkreport

Metro was planned during a brief overlap of master builders and transit-friendliness. I'm not sure the ARS would have happened had they waited another 5 years to start.

by Neil Flanagan on Aug 22, 2014 6:28 pm • linkreport

As bad as Fort Totten may be (and as dictatorial as China may be), Fort Totten can't be as bad as the two transfer stations between lines 1 and 2 in Beijing. Both lines use predominantly center-island platforms (despite the fact that they were probably built using cut-and-cover construction); the two transfers between lines 1 and 2--one at Jianguomen, one at Fuxingmen--were originally via a single staircase in the tiny area of overlap between the center island of the upper line and the center island of the lower line.

That arrangement was obviously flawed... so they eventually added a long (and, as I recall, fairly steep) cloverleaf between the far ends of each set of platforms. The staircases are still used to transfer from the upper to the lower platforms, but the clover leafs are used for the opposite direction.

When I first visited DC after living in Beijing for a few years I thought Metro's transfers at Metro Center and L'Enfant Plaza were a stroke of genius... obviously one set of platforms should be center-island, and the other should be side platforms! Of course, then I visited Hong Kong and learned how transfer stations should really be done....

by Steven H on Aug 22, 2014 9:47 pm • linkreport

The author seems to have missed an important variant, the combined side AND island platform, where is purpose of having both is to direct pedestrian traffic flow. This is often call a Spanish or Barcelona Solution.
The concept has boarding riders on either the side or island, and the exiting riders using the opposite. Platforms are serviced by one directional stairs and escalators. For busy stations the makes for much more efficient unloading and loading, and much better pedestrian flow in the general station.

by Jeff Hovis on Aug 23, 2014 2:09 pm • linkreport

@Jeff Hovis:
There's a paragraph about the Spanish Solution in the post.

by Matt Johnson on Aug 23, 2014 2:27 pm • linkreport

@Jeff Hovis

*ahem* "And while we don't have any examples of it in the Washington region, the "Spanish solution" can also be employed to reduce dwell times. The Spanish solution is where the doors on both sides of the train open. This makes it faster to unload and load the train. MARTA's Five Points station has this on both the upper and lower levels."

by Low Headways on Aug 23, 2014 2:27 pm • linkreport

Sometimes it almost makes one wish for a China-like dictatorship to build Shanghai Metro-sized networks under every urban center in the next ten years.
Then, you know, you remember that people generally value human rights over transit systems. But still.

It's not like Delhi isn't building a huge metro (120miles since 2002 with another 100 miles in the pipe) and isn't in a democracy.

by Richard on Aug 23, 2014 4:34 pm • linkreport

@Richard:
where is the next 100 mile system in the US?
Los Angeles.

LA's light rail is pretty nice. Doesnt get stuck in traffic too often as there is a lot of grade separations. But in terms of heavy rail, it only has 32 miles so far and it opened in 1990. With the purple line getting an extension it will grow, but at a slow rate.

by Richard on Aug 23, 2014 4:39 pm • linkreport

I doubt that it costs Delhi $2 billion/mile to build an underground metro line like it does here, though. Fix the out-of-control construction costs, and the other problems will solve themselves.

by jms on Aug 23, 2014 7:52 pm • linkreport

Gallery Place has to be one of the worst designed stations in the system.

It's not a cross intersection, but a T, meaning that everyone funnels in one direction to exit 3 of the stations 4 exits.

It's also a transfer station with a center platform below and side platforms above...just adding to the general confusion. You also have to enter the fracas of all the people exist the station through passage ways that are blocked by escalators.

And the side platform above means if you're heading toward Glenmont on the red but want or need to exit at 7th and H, you have to either go up and over (stupid) or down and under to the Green/Yellow (also stupid).

I really would like to know what they were smoking thinking that would work.

by Michael Cunningham on Aug 24, 2014 11:16 am • linkreport

@Richard

LA's light rail is going to grow massively in the next two decades with the funding from Measure R. There are already two extensions and one new line under construction with more to follow.

by MLD on Aug 24, 2014 2:17 pm • linkreport

Lord knows LA needs it. Can only be good for the prospects of transit projects nationwide if their network expansion becomes a success, and transforms one of the sprawliest cities there is.

I might even consider living there.

by SYH on Aug 24, 2014 2:39 pm • linkreport

Matt Johnson pretty much nails it on the reasons why island platform instead of twin platforms and vice versa.

The upper level of Metro Center, Gallery Place and L'Enfant Plaza have twin platforms to accommodate the simple design of the 90 degree crossing transfer station.

It should be noted that the contractors that bored the tunnels on the Red line north of Farragut North were given the option to bore 2 single track tunnels or one 2 track tunnel. The contractor that bored the tunnels on either side of Dupont Circle chose the 2 track bore option, That's why Dupont Circle has twin platforms. The contractor that bored the tunnels under Connecticut Avenue west of Rock Creek Park chose the 2 single track bore option.

The contractor that bored Dupont Circle tunnel used the drill and blast mining method to bore the 2 track tunnel. The contractors that bored the tunnels west of Rock Creek Park used a hard rock tunnel boring machine.

The same tunnel boring machine was used the bore the full length of both tunnel between Rock Creek Park and Pooks Hill Road. The lease on the tunnel boring machine was transferred from the first contractor that did the Connecticut Avenue segment to the contractors that did the remaining segment until it reached Pooks Hill Road.

by Sand Box John on Aug 25, 2014 9:32 am • linkreport

This is a fascinating piece and well done. Where do you get your info? If it's a book I'd like to read it myself.

by massysett on Aug 25, 2014 11:25 am • linkreport

The combination of forces that allowed the planning and construction of the Metrorail System might never occur again:
*strong federal leadership
*a cohesive regional vision
*willing federal funding partner with little competition from other cities for mass transit dollars
*canceling of freeways and Congressional approval to convert unused federal highway funding for Metro construction
*relatively low construction costs (compared to today)
*less rigorous regulatory environment

Each one of those elements was important to bringing about what we have today and *none* of them are present today.

by Sherman on Aug 25, 2014 2:22 pm • linkreport

Thanks for this great article!

by Alexander van der Berg on Aug 25, 2014 3:09 pm • linkreport

forgive me if I am wrong, but I thought Gallery Place is a t-intersection to avoid damaging or destroying its namesake, the national portrait gallery.

by lioki on Aug 26, 2014 7:15 am • linkreport

@Michael Cunningham, @lioki:
Gallery Place is designed like a "T" because of the routes of the Red and Green lines.

The Green/Yellow Line is under 7th Street, from U Street NW all the way to M Street SW.

The Red Line is under G Street from 15th Street to 7th Street. However, in order to swing south through Judiciary Square and to be able to get far enough south in time to turn north before Union Station, the line has to curve southeast immediately after crossing 7th Street.

Since the Red Line has to turn south so quickly, the crossvault (where the Green and Red vaults intersect) is off-center.

The National Portrait Gallery is on the southwest corner of 7th and G. It is not affected by either alignment, and wouldn't have been affected if the Red Line vault was centered on 7th Street, rather than on 8th Street.

However, I believe the width of the Red Line vault and platforms is affected by the presence of the National Portrait Gallery. But Sand Box John, who is very knowledgeable about Metro disputes that the Portrait Gallery required the Red vault to be narrower.

At any rate, centering the Red and Green vaults at 7th and G would have meant changing much of the Red Line alignment between Gallery Place and NoMa. The Judiciary Square station wouldn't have been possible (though perhaps another station nearby could've worked), and the Union Station station would've had to be located elsewhere, probably north of H Street, which is not convenient to the train station.

The Gallery Place station is designed like it is because of several constraints. There was no easy way to make the station look like Metro Center. And of course, now that it's built, it's extremely hard to alter the design.

by Matt' Johnson on Aug 26, 2014 9:21 am • linkreport

okay mr Johnson. thank you. I knew it was a technical reason why gallery was off-center.

by lioki on Aug 26, 2014 11:12 am • linkreport

oh, and I like your articles!

by lioki on Aug 26, 2014 11:15 am • linkreport

@ Matt Johnson

But did we really need Gallery Place & Judiciary Square at there present locations ?

Gallery Place & Archives are close enough to Judiciary Square.
Gallery Place should have been placed between 5th & 7th streets with entrances at H&7, 5th&G, 7&F each with entrances on all four sides of a corner with a combination of steps, escalators, and elevator all leading to the same level underneath the street

And placing a 10th Street entrance to Metro Center to take the place of the 9th Street entrance gone

Union Station should have been built a bit bigger regardless of how many lines run through it. It should have been placed further south to have one at Union Station building and another entrance south of Mass Ave such as at North Capitol & E and another west of the Post Office somewhere on North Capitol.

by kk on Aug 26, 2014 1:17 pm • linkreport

@kk:
But did we really need Gallery Place & Judiciary Square at there present locations ?
I cannot answer this question. That's up to you. I also can't change the decisions that were made in the 1960s.

However, what you're suggesting is still a "T"-shaped station. Just instead of it being off-centered to the west, it's off-centered to the east.

And by moving the platforms 600' east, there's not enough room to swing south to Union Station and still be pointed toward Brookland and Silver Spring.

It's easy to criticize decisions made decades ago. But your "solution" ignores the constraints the planners faced, and would likely have resulted in a more expensive project.

Whether or not it would have been "worth it" in our minds is beside the point. The decisionmakers at the time didn't think it would be worth it.

The point of my post (and my comments) is not to defend or criticize WMATA. It's to explain why certain things are the way they are.

by Matt' Johnson on Aug 26, 2014 1:26 pm • linkreport

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