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Ask GGW: Why is there a Metro tunnel in Tysons?

Several years ago, as the Silver line was being planned, there was a debate about whether to build the line underground through Tysons Corner. Eventually, the elevated option was selected, but there's still a tunnel. Reader Dennis McGarry wants to know why.

The tunnel portal. Photo by Dan Malouff.
Why is there a short tunnel on the Silver Line with no underground stops? Why not just build the entire track above ground? It seems like such a huge undertaking with little payback.
There are two short tunnels in Tysons (one for each track). They run about 1700 feet between Tysons Corner station and Greensboro station. The reason they exist is to cut through the highest point in Fairfax County, at 520 feet above sea level.

The tracks through Tysons are already high above the streets, and the climb between McLean and Tysons Corner is noticeable, especially from the front of a westbound train. Because trains are limited in the grade they can ascend, crossing this hill with an elevated viaduct would make the stations at Tysons Corner and McLean obscenely high.

In addition to the engineering and aesthetic challenges that a super-high viaduct would have caused, trying to keep the line elevated would have probably been much more expensive. So it was probably cheaper for the contractor to build these short tunnels than it would have been to keep the line elevated over the hill.

As a result, riders at McLean get a soaring view of the Tysons skyline (and in fact, you can see Bethesda, too), but a few minutes later, they find themselves riding underground, ever so briefly.

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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If only they kept that tunnel going...

by Randall M. on Jul 29, 2014 2:34 pm • linkreport

Bethesda, as seen from the station platform:

by BeyondDC on Jul 29, 2014 3:22 pm • linkreport

@Beyond DC - now, if only there was a transit option linking those two destinations, without a sojourn into DC. (And add to that a good transit option from Van Dorn/Landmark area to Tysons, and then on to Bethesda).

by JDC on Jul 29, 2014 3:30 pm • linkreport

Is the view of the Cathedral now blocked by the new high rise?

by jh on Jul 29, 2014 3:41 pm • linkreport

now, if only there was a transit option linking those two destinations, without a sojourn into DC.

like when the purple line comes down from Bethesda through McLean to Tysons?

by Richard on Jul 29, 2014 3:47 pm • linkreport

@Richard. If only that would happen.

by JDC on Jul 29, 2014 4:21 pm • linkreport


All you have to do is take a lane from the Legion Bridge, that's easy peazy, right? *sigh*

by Randall M. on Jul 29, 2014 4:29 pm • linkreport

Oh, so that's why that's called Pinnacle Drive there.

by iaom on Jul 29, 2014 4:36 pm • linkreport

If Purple line was heavy rail ran by metro, a Tysons/Bethesda/Silver Spring/New Carrollton line would be very possible over thirty years.

Guess what? The states don't want to make it happen.

by RailRider on Jul 29, 2014 10:13 pm • linkreport

"All you have to do is take a lane from the Legion Bridge, that's easy peazy, right? *sigh*"

No, you'd follow the Capital Crescent Trail to the Potomac, then cross on a new rail-only bridge and follow 123 to Tysons.

by Eric on Jul 30, 2014 8:00 am • linkreport

If we're dreaming, might as well make it a rail + bike & ped bridge.

by beetroot on Jul 30, 2014 10:57 am • linkreport

For all that I agree that the Silver Line sold have been underground throughout Tysons (and had express/local tracks) I am happy it's elevated. It makes that long long ride much more interesting.
(And I don't think it harms the urban/urbane potential in Tysons all that much either.)

by The View on Jul 30, 2014 10:58 am • linkreport

Purple Line on the Capital Crescent Trail to a new bridge to 123 to McLean & Tysons makes so much sense! It would connect major regional hubs and bring McLean in to the transit network mix. It would also create an awesome link in the regional bike network as well, linking the Cap Crescent Trail to the WO&D.

by TransitSnob on Jul 30, 2014 11:04 am • linkreport

What are some examples of communities similar to McLean that have rail transit?

by jh on Jul 30, 2014 11:09 am • linkreport

"and had express/local tracks"

No, no, and no. Just like with highways, "spot improvement" expansions do nothing to alleviate bottlenecks unless you widen way down the pike.

by come on on Jul 30, 2014 11:16 am • linkreport


It depends on what you mean by "like McLean" - same density residential but with a village core, same demographics, same proximity both to a metro area core and to an urbanizing edge city core? And what do you mean by rail transit? Do the Long Island Railroad and MetroNorth commuter trains count?

Anyway, the Purple line to Tysons discussion, though riper than it was a week ago, is still not ripe yet. Lets wait till the low hanging fruit to improve walkability are done. Meanwhile, it may be interesting to track the number of Md residents who use the SL to get to work in Tysons. That will be a factoid of interest in advancing the importance of a MoCo-FFX transit connection.

by CrossingBrooklynFerry on Jul 30, 2014 11:26 am • linkreport

I mostly mean things like: mansions, prominent residents, lower density. I'd be interested to know what other high-end established suburbs had some sort of rail built.

In other words, what has a chance of actually happening through Mclean? It seems that it's mentioned fairly often that the Purple Line should go through McLean and the immediate reaction by some is "Good luck getting more than 10 people in McLean to buy into that." Are there examples that counter that argument? Something along the lines of "McLean isn't much different suburb X and they successfully built a line through there."

by jh on Jul 30, 2014 11:42 am • linkreport


I recall reading in the Great Society Subway how some of the residents in upper NW were concerned about the noise and the impact of Metro. At the time, the area around Friendship Heights wasn't as dense so you could draw something from that.

by Randall M. on Jul 30, 2014 2:34 pm • linkreport

How high is Rhode Island Ave compared to Tysons Corner and McLean stations ?

I feel that when at Rhode Island Ave Station and looking down at the avenue it feels quite higher than Tysons Corner Station

What point is being counted as none of the stations are built on totally flat land and most of it has been smoothed to build on such as Rhode Island Ave as you can even see where the land should be higher from looking at the surroundings.

by kk on Jul 30, 2014 10:21 pm • linkreport


by Mike on Aug 1, 2014 2:33 pm • linkreport

"What are some examples of communities similar to McLean that have rail transit?"

In Europe, too many to mention. In the US, let's see...the Philly "Main Line" obviously springs to mind, although most of it is now more urbanized than McLean there are still some mansion-y parts. The LIRR Oyster Bay Line. The Boston MBTA line that goes to Weston. I suspect there's probably one in Chicago to Lake Forest, which is pretty upscale. All of these places are much older than most of McLean of course. And the irony of your question is that of course, McLean was a commuter rail town originally. Old Dominion drive was a rail line to Great Falls Park.

by Davester on Aug 1, 2014 4:10 pm • linkreport

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