After repeated delays, the completion of a Silver Spring transit hub is being pushed back again, with the opening now set for June and the cost now expected to total more than $100 million.

A project more than a decade in the making, the Silver Spring Transit Center is being built next to the Metro station in downtown Silver Spring and is expected to eventually accommodate nearly 100,000 people a day. The facility, which will be named for former U.S. senator Paul S. Sarbanes, will bring together Metro, Ride On, MARC, Amtrak, intercity bus lines, taxis and other transportation services.

Silver Spring residents and business owners have been eagerly awaiting the hub’s opening, which at one point was set for spring 2009 and has been pushed back at least seven times. After some early delays, construction began in September 2008.

County officials once expected the project to take two years and cost $75 million. Concerns about the facility’s long-term structural integrity and holdups in various other tasks have led to the new delay, according to officials.

“Certainly, no one is happy about the delay, and we all wish we could have been using it three years ago,” said Reemberto Rodriguez, the top county official for the Silver Spring area that includes the transit center and an appointee of County Executive Isiah Leggett (D). “But we all want it to be done right.”

Leggett disclosed the delay in response to a question at a public hearing Monday in Bethesda. David Dise, the county’s director of general services, said that cement covering the facility’s reinforced steel structure is thin at eight spots on the third floor. Project managers worry that the repeated chilling and thawing of the cement over successive winters could degrade the material and expose the steel. This could ultimately undermine the integrity of that part of the building, Dise said.

It remains unclear why the cement wasn’t properly laid throughout the top floor, according to county officials. The contractor, Foulger-Pratt, did not respond to a request for comment Tuesday or early Wednesday. Dise said that after construction is completed, county officials will examine what, if anything, went wrong.

Dise added that other work, including the installation of an underground ventilation system and groundwork along Colesville Road, must still be completed. He expects the construction to be finished by March or April, after which the Washington Metropolitan Area Transit Authority and the Maryland Transit Administration will begin a 60-day test of the grounds. The facility will open when the two agencies approve the site, Dise said.

“This is a very large and a very complex project,” he said. “Even though it looks like a simple building, it’s actually complex, and it takes longer to execute the work.”

An urban park that costs $600,000 to $800,000 and is part of the transit center will not be completed by the opening, Dise said. Foulger-Pratt has also said it would build a two-tower, mixed-use development near the transit center, but because of the weak economy, it remains unclear when it will be completed, according to county officials.

Leggett has described the transit center as vital for local economic development. County officials say it is a cornerstone of a downtown Silver Spring revitalization effort started under County Executive Douglas M. Duncan (D).

The project — including the urban park and the transportation hub — costs $101.4 million, an amount that has increased partly because of construction delays. The facility had cost $94 million when construction started, up from $75 million during the planning stage. County officials said they do not expect the newest delay to increase Montgomery’s costs.

Council member George L. Leventhal (D-At Large), who lives in nearby Takoma Park, said the delay is unfortunate. “There are all these exciting things in Silver Spring happening, but having a huge construction pit doesn’t help,” he said.

Taxi driver Abdul Seiwoh said he and other drivers want the center to open soon so they have an adequate space to wait for passengers. There is a makeshift taxi stand near the construction site, but there aren’t enough parking spaces, so drivers are sometimes ticketed for parking illegally.

But some passersby walking along Wayne Avenue from the Silver Spring Metro station on Tuesday weren’t concerned about the delay.

To accommodate transit users, county officials set up a network of temporary bus stops up the hill from the station. Winsome Brown, a 52-year-old Children’s National Medical Center nurse who has lived in Silver Spring for 19 years, was waiting at a bus stop at Wayne Avenue and Discovery Place. She said that she often uses the bus, because she lives in an apartment complex a few blocks away, and that she isn’t bothered by the speed of construction.

“It will be completed one day,” she said with a laugh.