Why Going Underground Makes Sense in Tysons Corner

By Roger K. Lewis
Saturday, February 17, 2007

Virginia Gov. Timothy M. Kaine (D) has an opportunity that's rare for political leaders: He can change his mind and become a hero.

In September, he chose not to pursue the tunneling option for Metrorail's Orange Line extension through Tysons Corner because he feared losing federal transit funding and delaying the project, now envisioned as an elevated line.

Now he can justify revisiting his decision and doing the right thing, thanks to new information and circumstances that emerged in the past few weeks.

Knowledge in hand today reveals that the tunneling option compares favorably with the elevated rail-line option. A tunnel could be built more quickly and at a lower cost than an elevated line, would be less expensive to maintain, and would be environmentally and aesthetically superior.

Consider new factors that the governor can act on.

The Federal Transit Administration has said that Virginia still has time to analyze and choose between building an elevated or underground line through Tysons. In a letter to Reps. James P. Moran (D-Va.) and Thomas M. Davis III (R-Va.), FTA Administrator James S. Simpson wrote: "FTA is willing to hold the aerial design in Preliminary Engineering while the Commonwealth decides whether to proceed with the aerial or tunnel option."

The final design can proceed only after the FTA determines that the preliminary design is highly likely to comply with federal regulations regarding transportation and land-use effectiveness, financial feasibility, timing and environmental impact.

Mindful of these policies, TysonsTunnel.org, a non-partisan, not-for-profit advocacy organization representing citizens, businesses and property owners, is confident that the tunnel would allow the Commonwealth to comply with federal requirements. It makes this assertion after raising $3.5 million for a consortium of highly qualified consulting engineers, architects and tunnel construction experts to thoroughly but quickly design the Tysons segment of the Metro extension.

In January, after working for three months, the team completed its A-to-Z engineering study for a 43-foot-diameter, single-bore tunnel through Tysons, including environmental analyses and architecturally ingenious designs for the four Tysons Metro stations. Station sites and tunnel alignment are similar to those for the overhead rail.

The key is large-diameter tunnel boring machines, a technology developed in Europe and used extensively and successfully around the world. More than 100 feet long, these gigantic machines can rapidly chew perfectly round self-supporting holes through dirt and rock, conveying excavated material backward to dump trucks while lining the bored tunnel with either sprayed-on concrete or prefabricated concrete panels.

I have seen the full set of design documents -- a whopping 786 sheets of drawings, a dozen technical reports, cost estimates. They are comprehensive and compelling.

The tunnel team has leveled the playing field for the competing options. The 3.4-mile tunnel (the total length of the extension to Dulles Airport is about 23 miles) through Tysons Corner has been designed to the same level of engineering development as the design of the elevated line, thus enabling the Commonwealth to make a fair comparison.

Of course, TysonsTunnel.org and its team have already made comparisons. They say it's all good news for the tunnel.

The total cost of the tunnel, at slightly more than $800 million, appears to be below the probable total cost of the elevated line. Moreover, the team predicts that the tunnel cost could be even less once the design is finalized and value engineering is completed. In addition, the tunnel option's life-cycle costs will be lower, a savings of about $5 million per year. And a tunnel's lifespan is potentially twice that of an aerial structure.

The team says the tunnel could be constructed about six months more quickly than the aerial structure, noting that tunneling avoids the need to move utilities or reconstruct roads.

Entailing almost totally underground construction, the tunnel option would be cleaner and much less disruptive of life above ground. Building an elevated line would require major road reconfiguration and bring years of severe traffic congestion exacerbated by construction trucks continually rolling through the heart of Tysons, along with construction noise and increased air pollution.

By contrast, with tunneling, dump trucks carrying excavated material will exit only at the ends of the tunnel on highway medians outside Tysons Corner.

But immediate and long-term aesthetic benefits still constitute one of the best arguments in favor of the tunnel and against an elevated line. Visualize a parade of tall, structural supports soaring over and slicing through the heart of Tysons. Leesburg Pike would never become a walkable boulevard.

Ponder the history of elevated, urban rail lines, most now demolished, that produced unwanted dirt, noise and vibration, became visual and physical barriers and compromised the value of abutting land.

Why build something that we will want to tear down a few decades from now?

Gov. Kaine can find political comfort in one other piece of knowledge. For all the reasons cited by tunnel advocates, Northern Virginia voters overwhelmingly favor the tunnel option, as does an independent panel of professional engineers.

And let's not forget Metro, which, strange as it seems, has little say in choosing between options, yet must ultimately operate and maintain the line. Metro officials prefer the tunnel.

For the governor, putting the tunnel back into play is not only a wise decision, it's an easy call.

Roger K. Lewis is a practicing architect and a professor emeritus of architecture at the University of Maryland.