A developer's proposal to bridge the turnpike along the more barren side of Mass. Ave. between Newbury and Boylston streets could mean several dramatic changes to the block beyond just towers covering what is now an open-air highway.

Samuels and Associates recently filed detailed plans for its Parcel 12 project, which would include a 40-foot-high "podium" across the turnpike, with 70,000 square feet of retail space opped by two towers, one 14 stories and filled with offices, the other 11 stories and housing either 150 residential units or a hotel. The podium roof not covered by the towers would be used as green space for the two towers.

If actually built, the development would be the culmination of discussions and planning that date to 1998.

Samuels says its project could include turning the current intersection of Mass. Ave., Newbury Street and the down ramp to the turnpike into a more friendly crossing for pedestrians, bicyclists and bus riders.

This would happen in large part by narrowing the intersection by moving the current ramp, which starts right at Mass. Ave. further west along the rump end of Newbury Street. Samuels, however, refers only to "the opportunity for the Massachusetts Department of Transportation to relocate the existing I-90 Westbound On-Ramp" and does not say who would pay for it.

In addition, Samuels says it would re-open a long-closed pedestrian tunnel under Mass. Ave. to the Mass. Ave. Green Line station so that people would no longer have to cross the busy street to get to a trolley.

Mass. Ave. in front of the project would get two dedicated bus lanes, a "cycle track" set off from the road and a wider sidewalk, Samuels says.

Samuels has proposed a two-level garage with space for 150 cars.

Parcel 12 offers an important opportunity to repair a barren section of Boylston Street and Massachusetts Avenue disrupted by the Turnpike, and to knit together distinct Boston neighborhoods: the Back Bay and the Fenway, and the South End and the City of Cambridge by creating a mix of dynamic mixed use development with ground-floor uses that will activate the street, repair the discontinuity in the urban street wall left behind by the Turnpike Extension, and improve the experience for pedestrians, bicyclists and motorists, as well as those using the wide array of nearby public transit options. Designed holistically to address nearby public infrastructure needs, the project has the capacity to improve a long overlooked swath of Boston's urban fabric.

The proposal is one of several that could remake the area around the turnpike where it crosses under Mass. Ave.

Samuels hopes to break ground on the project next year, with construction expected to take about two years.

The proposed view from Boylston Street:

Parcel 12:

Possible layout for a redesigned intersection and moved turnpike ramp:

Parcel 12 project notification form (146M PDF).