The Montgomery County Council voted unanimously Tuesday to let a taller building replace an existing office building on Wisconsin Avenue as a way to have a roomier Purple Line station in downtown Bethesda.

The zoning change is intended to encourage the office building’s owner to tear it down and redevelop the site to allow for a more spacious light-rail station. A new building at the site could be up to 250 feet high — or 15 to 20 stories — about 10 stories more than the existing building.

The Apex building at 7272 Wisconsin Ave. stands atop a tunnel that the Maryland Transit Administration plans to use as a western terminus for a proposed 16-mile light-rail Purple Line between Montgomery and Prince George’s counties. If the Apex building stays, a dozen of its large support columns will jut into the station platform, taking up room and impeding the flow of passengers, planners have said.

Redeveloping the building also would allow elevators between the Purple Line platform and the underground Red Line Metrorail station to be more visible. The Purple Line station’s ventilation system also could be incorporated into a new building, rather than in a 90-foot tower near Woodmont Avenue.

Most importantly, county officials say, a redesigned station would allow for a separate tunnel that would let joggers and cyclists on the Capital Crescent Trail continue to cross beneath busy Wisconsin Avenue.

Map of the proposed Purple Line

The greater density approved by the council would only take effect if the building is redeveloped in time to benefit a Purple Line station, planners said.

Whether the change in zoning will be enough to persuade the building owners to tear it down remains to be seen.

The building is owned by the American Society of Health-System Pharmacists, which has said it is happy with the existing structure. The building houses the trade group’s offices, as well as the Regal Bethesda 10 movie theater, the Food Wine & Co. restaurant and a For Eyes optical store.

David Silver, a Holland & Knight attorney for the pharmacist group, said the group is awaiting detailed proposals from several developers in the next 30 days. He said the group would need a plan that provides a financial reason to “tear down a perfectly good building.”

Time for a decision is short, as the state is seeking bids for a public-private partnership to design, build, operate, maintain and help finance the $2.2 billion rail project. Maryland transit officials have said the state does not plan to buy the building by exercising its power of eminent domain because it’s not necessary for the project and would be too expensive.