“Overpasses — get rid of them,” he said.

But canceling plans for new highways is easier than undoing built ones, even if they were often constructed to handle sky-high traffic predictions that either never materialized or that shifted to the Big Dig or MBTA lines that did not exist at the time.

Removing the overpasses ­requires a leap of faith on the part of the public, to accept that there can be more than one way to manage traffic, said Pete Stidman, executive director of the Boston Cyclists Union , an advocacy group. “After the Casey’s done” — the state has money and a four-year timeline for it — “people will witness how Forest Hills changes and momentum will build for taking down the others,” he said.

Overpass removal would be a bolder gesture than adding bike lanes on streets, incorporating more space for walkers and bicyclists on the rebuilt Charles River bridges, or even making room for bike racks or miniparks by removing some parking spaces. But advocates see all of these moves as a modest rebalancing, with considerable public space still devoted to driving and parking cars. Others see an onslaught against the automobile.

US Representative Michael E. Capuano , whose district includes the McCarthy, Casey, Bowker, and Rutherford, thinks the Department of Transportation is getting carried away.

“It’s amazing to me that aesthetics or one transportation mode seems to have captured the Commonwealth’s pocketbook,” the Somerville Democrat said. “I’m a biker, and I’m very supportive of making the city more biker friendly, but I’m also a driver, and 90 percent of my constituents still are, and I have bought in a long time ago to the concept of sharing the road, not taking the road away.”

Capuano said the state must do a better job of regional coordination, especially given the ­financial constraints. Removing the McCarthy could be a mistake, he said, without the long-awaited Green Line extension through Somerville or further widening of Interstate 93.

“If you think people are going to stop driving tomorrow just because you make it more difficult, I guess they haven’t seen the stories of LA, Washington, D.C., and other cities,” Capuano said.

But John O. Norquist, president of the international Congress for the New Urbanism , which promotes a return to the urban design of the prehighway era, said such projects have overwhelmingly succeeded in places as varied as Seoul and Milwaukee, New York City, and Portland, Ore.