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Take the Subway to the Game
The MCI Center in downtown Washington, D.C. required complex foundation design to integrate it with a subway system, but this resulted in a thriving entertainment complex that has revitalized the neighborhood
By Tom Gibson
On my last trip to Washington, D.C., I splurged a
little and spent the night downtown at the highrise Red Roof Inn (highrise
by D.C. standards -- zoning laws prohibit buildings taller than the capitol
building). I walked back and forth to the Washington Convention Center
and through the neighborhood surrounding the hotel and saw the usual city
sights: cars with horns honking, people bustling on sidewalks, sidewalk
vendors hawking flowers, and ethnic restaurants with culinary aromas wafting
from them. And amidst all that, construction crews toiled on a site the
size of a city block as they erected a new building, with cranes reaching
skyward hoisting steel beams and dirt-filled dump trucks beeping as they
maneuvered.
Only after awhile did I realize that the MCI Center sat across from the hotel. It blends with its surroundings, largely because it's no taller than buildings around it and it has no massive parking lot nearby. Typically, sports arenas are built in suburban areas in the middle of huge parking lots, so they stand out like shrines in an oasis. People drive to sporting events there, cars fill up the parking lots, and then traffic jams ensue as everyone leaves the scene afterwards.
But the MCI Center bucks that trend. Like the old Boston Garden in Boston and Madison Square Garden in New York, it lies in a downtown area at the hub of a major mass transit center, in this case the Washington Metropolitan Area Transit Authority Metrorail (Metro) subway system. The system links D.C. with surrounding suburbs of Virginia and Maryland, so people can actually take the subway from miles around to see Michael Jordan toss up jumpshots for the Washington Wizards or take in an Aerosmith concert.
Gary Kellogg, a structural engineer with
Delon Hampton and Associates, the engineering firm that handled the below-ground-level
civil and structural engineering for the MCI Center, served as a project
engineer for the job. Living in nearby Silver Spring, Maryland and frequently
working in downtown D.C., he can now reflect on the specter of building
something over subway lines in a tight city block. "I give Abe Pollin,
owner of the Washington Wizards, complete credit for having the vision
to bring a major venue to a downtown area that was in need of something
like this. He put it right by a Metro; that was a great idea. Putting
it by the metro, though, had tremendous challenges. I smile every night
I walk down in that Metro and there's an MCI event because I realize how
much we all went through to make that happen."
Building the MCI Center, a 1.1 million-square-foot sports facility and retail and entertainment complex, came about through a public-private partnership with the District of Columbia. The $260 million project began in 1996, and completion came in 1997. A joint venture formed by Ellerbe Becket, an architecture firm in Minneapolis, Minnesota that has designed a host of sports facilities, and Clark Construction Company of Bethesda, Maryland headed the design-build team that constructed it. Ellerbe Becket also served as the structural engineer for the arena above street grade, with staff engineers in its Kansas City office performing the work.
Delon Hampton & Associates (DHA) specializes in civil and structural engineering for all types of building structures and environmental and transportation infrastructure projects. Headquartered in Washington, the firm also has an office in Baltimore and regional offices in Silver Spring, Atlanta, and Los Angeles.
Based in New York City, Mueser Rutledge Consulting Engineers (MRCE) provided geotechnical engineering services and assisted in designing the arena's foundations. MRCE stakes a claim as the nation's first engineering firm to combine a geotechnical specialty with structural foundation engineering. Hugh Lacy, a partner in the firm, served as the project manager for MRCE. A civil engineer specializing in foundations and geotechnical work, Lacy has an M.S. in geotechnical engineering with a minor in structural engineering. MRCE does a lot of work in New York City and the Washington, D.C. area, commonly dealing with scenarios like the MCI Center. Lacy says, "We've done a lot of work over the years for the subway authority, so we're quite familiar with their requirements."
Located roughly equidistant between the White House and U.S. Capitol, the MCI Center sits on a 250,000-square-foot site bounded by Sixth and Seventh and F and H Streets. The site was previously a parking lot for many years. Two city-owned 11-story office buildings, each with three basement levels, occupied the northeast corner of the site, and these were demolished to make room for the arena.
The foundation design proved challenging and complex because one Metro subway line runs along the western border of the project and another east and west through the middle of the site, and the Gallery Place-Chinatown Station lies at the intersection of the two. Kellogg, also V.P. of professional services at DHA, recalls, "One of the big issues was even finding out where the subway was in relation to the building structure. It was a surveying challenge because it was very critical to locate the subway accurately."
MRCE determined construction impacts on the station and subway lines and devised methods to protect the structures from damage during foundation work. They prepared a monitoring program to verify tolerable movement of the station during construction. Lacy says in some cases, "we excavated right down to the top of the subway tunnel." Complicating matters, the parking garage that would become part of the complex passed above a subway tunnel before going to the street level. In addition, the previous entrance to the subway extended into the west end of the site and had to be demolished.
In its geotechnical work, MRCE also analyzed site conditions, soil and rock properties, and performance of subsurface materials. They evaluated alternate foundations and estimated differential settlement of the structure using different foundation types to accommodate concentrated loads in the vicinity of the subway. This was no easy task because the arena level is two floor levels below grade, and the parking garage over the southern half of the site extends two levels deeper.
As a testament to the difficulty, MRCE came up with a design that involved five foundation types, each as the best fit for a particular area. Kellogg exclaims, "That's totally unique in one building. I don't think I've ever heard of a project that had so many different foundation types." MRCE's design isolated the subway tunnels and allowed the subways to operate as the foundations were built.
In
one case, Lacy states, "We installed pilings and girders to span
over the subway so no load would be imposed on it. Some of the transfer
girders used 140-foot-long drilled socketed piers with a four-foot diameter
that were socketed into bedrock and loaded up to 4000 tons." On the
west side, where the station starts to open up, the spans had to be longer,
more than just the width of the subway, and they designed a huge transfer
girder to span the Gallery Place-Chinatown Station. Kellogg calls this,
"probably the biggest concrete beam I'll ever design in my whole
career. It was extremely complicated. It had tremendous loads from the
structure above."
The two office buildings previously on the site extended deeper than the MCI Center, so Lacy says, "we were able to leave a three-foot thick concrete mat which supported the two buildings. As a result, the cost of removing these mats was saved, and spread footings were installed above the older foundations." They put columns for the new building directly on the mat, with the spread footings allowing for columns in different places than before.
In the parking garage and much of the rest of the structure, the building was supported on conventional spread footings, as the natural soil had a good bearing capacity. However, the edge of the garage was supported on mat foundations to distribute the high edge load characteristic of a long-span arena.
As Lacy recalls, This was "definitely more difficult then the typical job. Normally, we like to have one foundation type for the whole building so you get uniform elastic deflections under the building. There was a lot of careful monitoring and concern about excessive deflections and that sort of thing. But fortunately, it proved to work very well."
With the foundations determined, design of other areas of the arena could proceed. A new wall was positioned inside the old wall from the previous office buildings using bracing, which saved the cost of demolishing these walls. A new entrance to the subway station was built with banks of escalators linked by a long corridor along the western edge of the site to the southwestern corner of the site. An exterior canopy links the Gallery Place Station with the center's main entrance. An elevator providing access for handicapped individuals was demolished and later replaced by two new elevators. Ventilation structures for the subway station that originally rose into the middle of the site were demolished, and new ventilation tunnels were dug to the north side of the site, coming up vertically just outside the arena. The above-ground portion of the facility consists of two levels of structural concrete and two levels of structural steel rising 110 feet.
Today, the 20,000-seat MCI Center hosts more than 200 sports, entertainment, and cultural events a year. The facility includes 110 luxury suites, 3000 club seats, offices, and practice facilities, along with the 400-space underground parking garage. It serves as home to not only the Washington Wizards but also the Washington Mystics WNBA team, Washington Capitals NHL team, and Georgetown University Hoyas basketball. Other events range from a Dave Matthews Band concert to the 2003 World Figure Skating Championships and Pet Fest America.
The MCI Center exemplifies the new trend of mixing sports facilities with retail and entertainment space to take advantage of having a facility open year-round. Nick & Stef's Steakhouse, F Street Sports Bar, Acela Club Restaurant, and Modell's Sporting Goods have all found a home in the center.
So does placing a sports arena smack over a subway station encourage people to use mass transit to get to sporting events? Kellogg replies, "Absolutely. Most people take the Metro to come to these events, at least by my observation. That's thrilling to me. And it really helps this downtown area. Lots of restaurants have popped up all over the place. There's a whole new nightlife down here because of this building. Other businesses have grown up."
The recently-opened Washington Convention Center, where I attended a conference, is an example of what Kellogg means. Furthermore, peering out my hotel window at night, I saw the construction across the street continuing under the lights. I realized that much of this revitalization going on in the thriving neighborhood around me was spawned by the MCI Center. And Kellogg mentions that DHA is now working on Gallery Place, a mixed-use building that will feature restaurants, theaters, residential quarters, offices, and much more. With enticements like this, thousands of people now flock to this part of Washington, D.C. -- and they don't have to drive their car to do it.
Progressive
Engineer
Editor: Tom Gibson
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©2004 Progressive Engineer