Rail Route In Tysons An Uphill Challenge
Engineers Debate Aerial Track, Tunnel
By Peter Whoriskey
Washington Post Staff Writer
Wednesday, July 27, 2005; B07
Most people barely notice the hill that Tysons Corner is built on,
even though, at about 515 feet above sea level, it looms as
Fairfax County's highest natural summit. For them, the slope demands
no more than a nudge at the accelerator.
But for the engineers designing a Metrorail line to the area's malls
and offices, the hill at Tysons Corner presents a significant
obstacle: Railroad tracks generally must be laid flat or at very
slight inclines. Otherwise, the steel wheels lose traction.
"It's just a hill to most people, but for us, the hill in
Tysons Corner is one of our biggest engineering challenges," said
Dulles Project Director Sam Carnaggio.
In fact, the fate of the entire rail project turns at least in part
on the $100 million conundrum posed by the slope at Tysons Corner.
The effort to extend Metrorail through Tysons, a kind of holy grail
for Northern Virginia commuters, has reached a critical
By late August, project managers must cut the estimated
$2.4 billion cost by more than 20 percent -- or else scuttle
the idea, they said. And as engineers review cost-cutting
design alterations, no single greater dilemma exists than that
presented by the hill.
Engineers could excavate a mile-long relatively level tunnel through
the hill. But that could be done only at a budget-busting cost
of $132 million, cost estimators say, and project managers
have identified the elimination of any underground passage as
the largest single cost savings they can make.
Running tracks on or close to the ground would disrupt traffic too
So the alternative to the tunnel is to cross the hill on
elevated tracks, but that creates its own problems. The aerial
tracks and their supports could look like a concrete scar
running through Fairfax County's "downtown," many fear. Making
matters worse, engineering constraints could force the tracks
to be built as high as 80 feet aboveground.
Tysons Corner is the capital area's second-largest job center and
home to two regional malls, and the county's comprehensive
land development plan has long envisioned a rail line
there -- preferably underground.
"A tunnel rather than an elevated alignment is the preferred
mode," according to the comprehensive plan. Aerial tracks would,
among other things, "intrude visually."
The dire cost-cutting challenge for the rail project arose last
month, when engineering firms reviewing the plan, which would
extend the Metro system from West Falls Church through Tysons
Corner, estimated that its price had risen 60 percent,
to $2.4 billion -- way beyond what planners and public
officials consider feasible.
Not only does the project lack the budget for $2.4 billion,
planners said, but the construction effort also would flunk
federal cost-effectiveness standards at that price.
"We're looking at everything to find savings," said
Josh Sawislak, deputy project director for the Virginia Department
of Rail and Public Transportation, which is leading the
Among the proposed cost-cutting measures are a reduction in the
number of rail cars, a drop in the size of the train platforms and
the elimination of some elevators and escalators at the station.
There are drawbacks to virtually every cut, however: Reducing
the number of rail cars would reduce the number of trains running
at rush hour, one of the key reasons for building the project;
shrinking the size of platforms could create safety problems;
and eliminating escalators and elevators could run afoul of
the Americans With Disabilities Act.
Rejecting those other changes, however, leaves only the issue of
Aside from the former county landfill near Interstate 66 and
West Ox Road, which rises to 567 feet above sea level, the
Tysons hill ranks as Fairfax's highest elevation, county
"It's a relatively flat county," said Charles Grymes, who
teaches geography at George Mason University. "Unfortunately,
railroads can't climb hills worth a hoot."
The largest single proposed cut -- $132 million -- involves
elimination of the mile-long tunnel that was to have traversed
the hill at Tysons Corner and included one underground
But completely eliminating that tunnel would raise railroad
tracks as high as eight stories high
The reason for the height is that railroad tracks can safely
operate at only slight inclines. Metro guidelines generally
limit slopes to no more than 4 percent, meaning that the tracks
can drop no more than 4 feet over 100 horizontal feet.
If aerial tracks were run from the top of the Tysons hill,
the ground would slope down much faster than the train tracks
could, leaving the tracks several stories in the air at
times. Eventually, the track would catch up with the ground, but
in the meantime it would create big gaps between the ground and
Engineers call this "chasing grade."
Abandoning the tunnel configuration could cause other troubles
The property owners in Tysons Corner, who have agreed to put
up as much as $400 million in tax money toward the project,
based their offer on the original configuration of the train route.
That offer might be rescinded if the configuration changes
"To the extent that there is a significant change, the county
runs the risk of having to go back to landowners in order to
spend the tax money," said John McGranahan, a lawyer who
organized the tax district.
© 2005 The Washington Post Company