In a dispute over whether the Silver Spring Transit Center is structurally sound, Montgomery County and general contractor Foulger Pratt will bring in a third engineer to analyze the situation and hopefully resolve the differences, David Dise, director of the county Department of General Services, said Thursday.

On the one hand, Parsons Brinckerhoff, which designed the structure, has found that more than half of the concrete on the second and third levels is either too thick or too thin. The third level is planned to hold 32 bus bays for Metro, Maryland Transit Administration and Ride On buses. Several areas are cracked or flaking, and the steel support beams are exposed in some areas. As a result the concrete does not meet the American Concrete Institute's or Metro's standards.

Fixing the errors could mean tearing down the $101 million structure and starting over, Dise said, or it could mean simply filling the cracks and reinforcing it — or there could be any number of other solutions. Foulger Pratt should pay for the fixes, Dise and other county officials have emphasized.

But Foulger Pratt says the structure is more than strong enough to hold the weight it needs to and only needs a coat of sealant, which was part of the plan anyway. "There's no call for anything close to [tearing it down]," said firm principal Bryant Foulger.

Whatever the solution, the structure ultimately will need to meet Metro's requirements before the transit agency will use it.

Metro, in turn, needs to see "a proper assessment of the structure's design and construction" before determining what that solution is, said spokeswoman Cathy Asato. "We have infomed [the county] that we would not accept the facility as presently constructed."

The county and Foulger Pratt also disagree on how long it will take to come to an agreement. Dise said he expects a cure to take six months, while Pratt said he expects it sooner. Without the concrete issues, the structure would likely have opened by the end of August, Dise said, and Foulger Pratt predicted in a recent analysis that it will still meet that deadline.

If the county and the contractor cannot come to an agreement, the matter will likely be taken to court.