The closure of a lightly-used Turnpike on-ramp from Clarendon Street under Boston’s Back Bay Commuter Rail station will add considerable value to a major redevelopment proposal on the adjacent block, and keep traffic from a nearby parking garage away from the busiest sidewalks around Back Bay Station.

The ramp occupies valuable real estate beneath the proposed “Back Bay/South End Gateway Project,” a redevelopment scheme that would renovate Back Bay Station and add three high-rise towers around its periphery. The 2,000-stall parking garage that currently hulks over the station would largely remain in place.

During that project’s approval process, one of the more significant issues that emerged concerned was the developers’ proposal to relocate an exit ramp for the parking garage from Trinity Place to Dartmouth Street, just steps away from the busy entrance to Back Bay Station.

“WalkBoston does not think that a project design that includes a garage exit ramp across the Dartmouth Street sidewalk is acceptable,” wrote WalkBoston executive director Wendy Landman in an August 2017 letter to the state Executive Office of Energy and Environmental Affairs and the Boston Planning and Development Authority (BPDA).

“Putting the interests of drivers above those of the tens-of-thousands of pedestrians who use this sidewalk is not an appropriate use of public space.”

In its November 2017 meeting, the planners of the BPDA board reviewed and approved two designs for the project: a “base design,” where the on-ramp remains in place and the garage exit ramp is moved onto Dartmouth Street, plus an alternative design where the Turnpike ramp is eliminated, and the garage ramp remains on Trinity Place.

The memo noted that the second option, without the Turnpike ramp, would also allow the construction of an additional 13,200 square feet of floor area in the office building above.

The BPDA’s approval memo states that “to be responsive to possible permitting and feasibility constraints, either one of the two proposed options for the Garage West Parcel are authorized.”

In a public hearing Tuesday evening, officials from MassDOT stressed that their decision to close the ramp was made independently of the development proposal, and was being pursued because the ramp has significant safety issues.

But Mark Boyle, Administrator of the Office of Real Estate and Asset Development for MassDOT, acknowledged at the meeting that the developers were making a “significant compensation to the Commonwealth, both in terms of cash, and in other commitments,” such as by providing construction staging areas for an upcoming renovation of the Turnpike’s tunnel under the Prudential Center, and by completely renovating the Back Bay Station concourse as part of their project.

Boyle reported that MassDOT had already received $37 million from the developers, and that the agency was expecting another $20 million to be delivered on the final approval for the proposed office tower at the corner of Stuart and Dartmouth Streets – the tower whose size depends in part on whether or not it would need to make room for the Turnpike on-ramp in the basement.

That office tower is now being reviewed by MassDOT for its final approvals. Boyle reports that the plans under review reflect the “alternate” design, with the on-ramp eliminated and the garage exit ramp relocated to Trinity Place.

The Clarendon Street on-ramp will close to traffic for good on at midnight on Monday, September 2nd.