AMHERST - Preservationists are trying to ensure a century-old shelter originally built to serve passengers on an electric trolley line continues to be used as a PVTA bus stop by University of Massachusetts students.

But the effort by Preserve UMass, a 150-member organization of former and current UMass professors, staff, alumni and professionals dedicated to recording the history of the campus, comes after the Massachusetts Historical Commission has apparently given the go-ahead for the university to demolish the 1911 Craftsman brick building.

Located on North Pleasant Street at the heart of the campus, the Waiting Station Shelter was part of what was known as the Amherst and Sunderland Street Railway, which started in 1897 going along North Pleasant Street to North Amherst and eventually into Sunderland. It also ran south to the Notch, where it connected to a line to Holyoke.

Though the structure has long been used by the university as a bus stop, UMass spokesman Ed Blaguszewski said the shelter is expected to make way for the new $85 million Academic Classroom Building and the associated infrastructure just south of the Hasbrouck Physics Laboratory.

"What we confronted here was a situation in which to put up the new facility we needed to substantially upgrade the utility infrastructure that runs right through where the Waiting Station is," Blaguszewski said.

Consultants, he said, estimated it would cost $145,000 to move the building and an additional $55,000 to put it back in place.

"We concluded it was not prudent and financially wise to reconstruct it brick-by-brick and figure out where we'd put it up," Blaguszewski said.

Joseph Larson, corresponding secretary for Preserve UMass, said his concern is that the building will be demolished before the university obtains another cost estimate for moving it.

"Our position is that the university's cost estimate for preservation is based on the most expensive process, brick-by-brick deconstruction and brick-by-brick reconstruction," Larson said. "We believe that it can be moved entirely, stored on beams a short distance from its present site, and then returned to its original location, or nearby, for a lower cost."

Larson said Preserve UMass would like the Massachusetts Historical Commission to require this second cost estimate, which, if less expensive, could cause the university to alter its decision to tear down the structure.

The Waiting Station, Larson said, is one of only a handful of elements that remain from the former trolley lines, which include a storage barn on Cowls Road that was the subject of the town's demolition delay bylaw more than a year ago and the Department of Public Works headquarters on South Pleasant Street.

The demolition delay bylaw, used by the Historical Commission for structures and landscapes deemed significant, doesn't apply to buildings on state property.

A Dec. 23 letter from the Massachusetts Historical Commission seems to indicate the demolition can begin as long as the university photographs the structure and puts associated documents in the campus archives.

"Mass Historical Commission is in agreement that we can proceed with that [because] we're documenting its history," Blaguszewski said.

But Larson said the state commission may have been hasty in sending the letter and Preserve UMass will try to have the agency reconsider. Larson argues the university didn't follow the correct process of notification, waiting until six months after plans were developed.

Larson said that Preserve UMass will ultimately accept what the state Historical Commission decides. "They are the final authority on this," he said.

Previously, Preserve UMass raised questions about the process campus administrators used to pick the site for the $85 million Academic Classroom Building and whether it would adversely affect the Campus Pond.

A state law says that any public body planning a project must notify the state Historical Commission unless it clearly does not have a potential impact. This notice should be given to the state commission as early as possible in the process, the law says, before any action is taken.