The Pentagon should foot more of the bill for fixing traffic problems around military bases that are receiving thousands of new workers under a national realignment plan, a report commissioned by Congress said Monday.

Worsening traffic around some of the bases could be harmful to the military, which has previously left local and state governments to pay for most off-base transportation improvements, according to recommendations in the report by the National Research Council's Transportation Research Board.

The report looked at six large bases: Fort Meade and the National Naval Medical Center in Maryland, Fort Belvoir in Virginia, Joint Base Lewis-McChord in Washington, Florida's Eglin Air Force Base and Fort Bliss, Texas.

They are among 18 domestic bases slotted to expand as others are closed or reduced in size under the periodic realignment. The current plan was approved by Congress in 2005 and is gradually being implemented.

The report warned that realignment and other sources of military growth, including troops returning from two wars, are already causing "severe" transportation problems at most of the six facilities studied.

"The resulting traffic delays will impose substantial costs on surrounding communities and may even be harmful to the military," the report said.

But the Defense Department considers its responsibilities for off-base transportation needs to be limited, the report said.

To help ease congestion, the report recommended that the Defense Department expand its only program to help pay for transportation infrastructure off-base. The Defense Access Roads program currently requires that traffic double due to base expansion for a metropolitan area to be eligible.

The Pentagon largely leaves local and state authorities responsible for off-base transportation needs, even if decisions by the Pentagon increase congestion, the panel found.

"This policy is unrealistic," it said.

Communities that benefit economically from the military should pay their fair share, and the military and local communities should improve communication in planning infrastructure improvements, the report said. The report also noted that the recession has reduced tax revenues far below levels needed to maintain roads for growth unrelated to the military.

Congress should consider a special appropriation or reallocation of federal stimulus money to pay for near-term improvements in the communities most severely affected by base realignment, the report recommended.

The report calls particular attention to the Washington, D.C., area, where three of the six bases in the case studies are located. The report describes the metropolitan area as the second-worst for travel delays nationwide.

At Fort Meade, at least 5,700 additional workers are expected to arrive by September because of base realignment, with up to 13,300 others arriving due to growth at the National Security Agency and increased contractor presence at the base. The report cited $786 million in needed highway improvements that do not have funding around Fort Meade.

Robert Leib, special assistant for base realignment with Anne Arundel County in Maryland, said county officials have long known there is not enough money or time for needed improvements.

"It's going to be a very intense experience driving around Fort Meade for a while," Leib said.

He said there already are delays as long as 30 minutes to enter the facility, and he hopes the new report will catch federal officials' attention.

U.S. Sen. Benjamin Cardin, D-Md., said traffic congestion and overwhelmed mass transit threaten the effectiveness of the base realignment process.

"The consequences of inaction would gridlock our national security, as well as affected urban and metropolitan areas," Cardin said.

In Washington state, The drive past Joint Base Lewis-McChord has long been a headache for commuters on the stretch of Interstate 5 between Tacoma and Olympia. But it has worsened noticeably in recent years.

In the Florida Panhandle, roads surrounding Eglin Air Force Base are already being widened and rerouted in response to the arrival of thousands of newly assigned Army and Air Force members. The Army's 7th Special Forces Group from Fort Bragg, N.C. is relocating to the sprawling Florida base. Training for the Joint Strike Fighter F-35 stealth jet will also take place on the base.

"We are excited about this spurring real-estate and housing construction, about all of the potential economic impact," said Okaloosa County Commissioner Dave Parisot, a retired Air Force major.

Parisot said the military is paying for some roadwork that is designed to ease congestion near the bases.


Associated Press Writer Melissa R. Nelson, in Pensacola, Fla., and George Tibbits, in Seattle, contributed to this report.