Build it, and they will come. 

That movie-inspired adage defines the looming transportation challenge for areas gaining population under 2005 Base Realignment and Closure (BRAC) program, according to a new report from the Government Accountability Office (GAO).

Based on a study of 18 communities expected to undergo substantial BRAC-related growth at adjacent military facilities, the report concludes that the influx of thousands of new workers and dependents will have a significant effect on local highways and transit systems, “but long-term costs are uncertain and direct federal support is limited.”

Few areas will feel the effects more than metropolitan Washington, DC. More than 24,000 new workers are bound for Fort Belvoir in Virginia, while Fort Meade and the Aberdeen Proving Ground in Maryland will gain 7,000 and 3,400 new employees, respectively.

The Bethesda National Naval Medical Center will add 2,500 new employees, but its traffic impacts will likely be amplified by the addition of patient family members and visitors, medical support services, and other factors.

To the south, Fort Lee will add more than 10,000 new workers, while 3,600 more workers are on their way to Marine Corps Base Quantico.

Nationwide, the estimated cost of near-term transportation projects to address these challenges is $2.0 billion; improvements in metropolitan Washington account for more than half that amount.

But the report admits those figures are subject to change, as it does not include all potential projects nor does it account for pending relocation decisions and other uncertainties.

While the Dept. of Defense’s Access Roads Program is providing some assistance to assist BRAC communities with infrastructure needs, the lack of dedicated funds leaves most road and transit improvements in competition with other projects for financing.

A miraculous appearance of needed funds might be cause for relief, but little else. The GAO report notes that while major infrastructure projects have nine- to 19-year timeframes, BRAC mandates that the relocation of 123,000 civilian and military workers be completed by 2011.

Small wonder, then, that Rep. Jim Moran (D-Va.) predicted back in July that “chaos” would ensue from BRAC’s massive personnel shuffling, and appealed to the Pentagon to reconsider bringing so many people to Ft. Belvoir so quickly.

But with a third of the installation’s population growth slated to arrive in late 2011 with the opening of the National Geospatial-Intelligence Agency’s new 2.4 million-sf headquarters, and a new hospital and office buildings already coming out of the ground elsewhere at the facility, it seems a little late for such a major administrative about-face.

Some steps to cushion the effects are underway, particularly the Fairfax County Parkways 2-mile extension and link with I-95, which is being funded by a combination of state, military, and stimulus sources.

The GAO report also describes how Maryland’s transportation officials are scrambling to identify and prioritize low-cost, easily implemented intersection improvements as a short-term solution while they look for ways to finance larger, more complex projects.

With neither a quick fix nor a reliable long-term funding source in sight, metropolitan DC and other BRAC-boosted communities have no choice but to cope with these infrastructure issues as best they can. Their roads may be clogged, their transit systems overburdened, but these challenges are far more desirable than those confronting communities that are losing population and commerce due to BRAC.

Still, the infrastructure conundrum calls to mind another familiar saying: be careful what you wish for, because you might just get it.