A top Metro official told the Montgomery County Council on Tuesday that the agency will not commit to taking control of the Silver Spring Transit Center until it sees the results of additional tests on the troubled $120 million train and bus hub.

A 2008 agreement calls for the county to turn over the facility upon completion to the Washington Metropolitan Area Transit Authority, to become part of its regional system. The agency said in April that the center was so compromised that it wouldn’t serve as operator under any conditions. It has since backed away from that stance, but it still contends that it can’t accept the center until it has a better idea of how much design and construction problems — which have put the project more than two years behind schedule and tens of millions of dollars over budget — will increase maintenance costs.

A 2004 Metro analysis placed annual maintenance expenses at $2.5 million, a figure that will now be considerably higher — both in 2013 dollars and additional costs created by a series of issues, including cracked and insufficiently thick concrete and the absence of supporting steel in parts of the roadway.

Metro is looking for the most favorable terms it can extract from the county for picking up some of the added costs.

Rodrigo Bitar, assistant general manager for Metro, told the council that although the agency is prepared to run buses out of the center, it cannot commit to taking control of the facility. He said the agency expects maintenance obligations on the three-tier concrete and steel structure to be “extraordinary.” He also said that although repairs are likely to mitigate construction issues, they may not solve them.

Concrete issues at the Silver Spring Transit Center

“I’m very hesitant to say, ‘Sure, we will take it and operate it,’ ” said Bitar, whose appearance before the council was the first by a Metro official since an independent consultant reported that the center could reach its 50-year life expectancy but not without major repairs.

Metro recently requested two new tests, which an engineering firm is performing: one assessing the waterproofing of the structure, and the other confirming the ability of certain key concrete girders and beams to withstand the stresses caused by heavy bus traffic.

Council members said they understand Metro’s concerns but expressed displeasure with the message that it is prepared to walk away from the project.

“I think my colleagues and I have been disappointed in WMATA’s public posture to date,” said council member Roger Berliner (D-Potomac-Bethesda).

Council member Marc Elrich (D-At Large) reminded Bitar that Metro has partnered with the county since the beginning of the project, and it signed off on all aspects of design and construction, which have been problematic.

“We share a mutual responsibility for those results,” Elrich said. “It seems to me there is a case for looking at how [maintenance costs] get apportioned. There’s not a case for walking away.”

County officials still have no opening date for the center.

David Dise, the county’s director of general services, who is overseeing repairs, said work is on track to begin in July, pending approval by Metro and the county’s Department of Permitting Services. The first step is to add supporting steel to two 10-foot by 40-foot sections of roadway. The county had originally intended to rip out the strips entirely but decided to avoid demolition because of potential damage to conduits and beams. Later in the summer, workers will add a polymer overlay to cracked concrete slabs.

“The good news is that work is progressing and collaboration is alive and well,” Dise said.