The Silver Spring Transit Center was found unsafe and in need of major repairs. (Sarah L. Voisin/The Washington Post)

The long-delayed Silver Spring Transit Center may open by late summer or early fall, Montgomery County officials said, but there is uncertainty over how to complete needed repairs — raising the possibility that the work could be done after the opening date, perhaps on nights or weekends.

Officials also disclosed this week that County Executive Isiah Leggett (D) has convened a working group of independent engineering and construction experts, headed by former Lockheed Martin chairman and chief executive Norman Augustine, to review plans to repair the troubled center and make recommendations.

The group, formed by Leggett several months ago without any public announcement, is expected to deliver a report sometime in the next couple of weeks.

The $120 million facility on Colesville Road, originally viewed as an essential element in the revitalization of downtown Silver Spring, was intended to be a unified hub for Metrorail, Ride On, MARC, Kiss and Ride and taxi service.

But the project is more than two years behind schedule and tens of millions of dollars over budget. Design and construction issues, including persistent cracking in the three-level concrete structure, have turned the venture into a major embarrassment for Leggett and an issue in his campaign for a third term.

Leggett is under pressure from his challengers in the June Democratic primary — especially former county executive Doug Duncan — to be more explicit about plans for the repair and opening of the center. Duncan has said that the county is plagued by “paralysis by analysis” in trying to put the project back on its feet.

Leggett insists that he has been proceeding deliberately and responsibly. At a political breakfast in Rockville on Monday — and in a subsequent interview — he said he hoped to turn the building over to Metro, the facility’s operator, by early summer.

“June if the weather cooperates, maybe July,” Leggett said, referring to the time and warmer temperatures that workers need to pour a new layer of latex-modified concrete on roadways to address the cracking.

Once it is given control of the center, Metro will have 60 days to evaluate the facility and decide whether to accept it. If the review goes smoothly, the center could be open by late summer or early fall.

The more problematic repair involves reinforcement of about 250 interior concrete beams and girders that must absorb loads from the hundreds of buses that will use the center every day. Officials emphasize that this repair involves the long-term durability of the facility, not its safety.

But the major players in the project — the county, its engineering consultant KCE, Metro and designer Parsons Brinckerhoff — are not in agreement as to how, or even if, the beam and girder work should proceed.

KCE and the county say the beams and girders need to be strengthened to better withstand torsion, the twisting force exerted on concrete when it is bearing loads such as the buses. Parsons Brinckerhoff, the giant international engineering and design firm, has maintained that according to industry standards, it was not required to calculate for torsion when designing the center.

A Parsons representative did not return a phone message as of Tuesday evening. Metro spokeswoman Caroline Laurin said in a statement: “We continue to work cooperatively with Montgomery County but we’re unable to speculate on a date when the solutions to contractor issues will be implemented.”

David Dise, general services director for Montgomery County and the lead official on the transit center, said it is possible that Metro — which is, in effect, the county’s client on the project — could begin operations at the center before making a final decision on the beams and girders. The decision would hinge on whether Metro wanted to do the work now or to wait to see how the building performed in service, Dise said.

Also complicating the issue is how the repairs would be paid for. County and Metro officials are discussing a special escrow account, funded by a surety bond financed by Parsons, to pay for additional repairs caused by faulty design.

Repairs performed after the opening could involve a complete or partial shutdown of the center at night and on weekends so the work could be done, Dise said.

Augustine’s group is expected to weigh in on the issue sometime in the next couple of weeks.

In a brief phone interview Tuesday, Augustine, who lives in Montgomery County, said Leggett asked him to examine three issues: repair plans, cost and a likely schedule for opening.

It would be up to Leggett to make public any report that the group completes, Augustine said.

Other members of the working group are Donald Vannoy, professor emeritus of civil and environmental engineering at the University of Maryland; Kenneth O’Connell, a consulting engineer with the firm O’Connell & Lawrence; and Algynon Collymore, a construction expert with D.C. Water.