Passersby bemoan a toppled row of trees

But yesterday, the pretty stretch was laid low, with 20 fully grown lindens reduced to 2-foot stumps. Riding his bike by the newly barren scene, where twigs, branches, and sawdust were strewn across the snow, the 59-year-old clinical researcher could hardly believe his eyes.

“I was absolutely appalled,’’ he said. “They were really, really lovely, especially in the summer. Then, bang, just gone. A lot of people are going to miss them.’’

Construction workers felled the trees this week as part of a $40 million project to repair Craigie Dam Bridge and Drawbridge, which carries Route 28 from Cambridge to Boston. Officials with the state’s transportation department, which is supervising the work as part of a $3 billion campaign to restore structurally deficient bridges across the state, said removing the trees was necessary to create a broader thoroughfare.

“It’s essential for the work that’s being done,’’ said Colin Durrant, a spokesman for the department. “At the end of the day it’s going to be beneficial for people.’’

The dam bridge was built in 1906. The drawbridge was built in 1910 and replaced in 1962.

When the project is completed in summer 2011, workers will plant 24 trees and install a retaining wall. The Highway Department is donating some of the wood from the felled trees to the Massachusetts College of Art and Design for carvings.

Officials held several meetings in recent months to discuss the project with the community, Durrant said. But for the legions of walkers and runners who traverse the narrow ribbon of pavement, along with the crowds filing into the museum on a chilly Friday, the lowly line of stumps was a startling and thoroughly depressing sight.

“Dismal,’’ Joanne Myers, a 43-year-old from Cambridge, said as she paused in front of the museum during a walk on her lunch break. “It looks lonely and cold, just like this weather.’’

Museum employees knew the trees were coming down, but were saddened by their departure just the same. Still, the venerable trees had long outgrown their sliver of brick-enclosed sod, and officials said it was time for them to go.

“We miss them already,’’ said Jonathan Burke, vice president for visitor services and operations. “But they have been there a very long time, and they just didn’t have enough room. Some of them didn’t look so healthy anymore.’’

Burke praised state officials for their cooperation on the project, which he said would sharply improve the high-volume walkway.

“The plans we’ve seen will make things better for pedestrians of all stripes,’’ he said.

Wendy Landman, who directs the pedestrian advocacy group WalkBoston, agreed that the current sidewalk, which is just 5 feet wide, is far too narrow to handle the rush of cyclists and runners who whip past the museum to the Esplanade.

“What’s there now is not even adequate for a pedestrian,’’ she said. “This is the only way to close the loop.’’

Landman said pedestrian and cycling advocates pressed highway officials to broaden the sidewalk and add bike lanes in both directions to the road. Given the traffic on the bridge, however, many riders will stay on the pedestrian path.

“This is used by families, children, everybody,’’ she said. “It’s an incredibly constrained and busy spot.’’

But others were frustrated by the tree removal, and skeptical that replacements would ever be planted.

Many, including Engelstad, said it would take years for the new, younger trees to achieve the fullness of their predecessors.

Bob Zimmerman, executive director of the Charles River Watershed Association, said he was taken aback when he first encountered the treeless landscape yesterday. The trees had added a dash of natural beauty to the urban backdrop of traffic jams and rumbling trains.

“Now it’s a very different experience,’’ he said.

When spring comes, and leaves return, the trees will be missed even more, many said. For those straining under a warm sun, their shade was an oasis.

“Every little bit helps,’’ huffed one 20-something runner before she continued on her way back to Harvard Square.