Kendall Square’s rooftop garden is fenced off Oct. 3 in preparation for construction. (Photo: Marc Levy)

A linear park is proposed to run along the Grand Junction rail line in Kendall Square.

While a rooftop garden loses roughly half its space, plans for a Kendall Square park with plazas, sitting areas and a walkway get a hearing Thursday, with businesses and residents encouraged to attend, view designs and provide comments by officials at the state Department of Transportation and Cambridge Redevelopment Authority.

As described by the city, this “Innovation Boulevard project” is for a linear park running alongside the Grand Junction rail line — at the westerly edge of Galileo Galilei Way between Main Street and Binney streets, as well as between residential neighborhoods and academic and business institutions.

It’s intended “to create a landscape that enhances the overall Kendall Square community” and be “an attractive open space for use by residents, students, faculty, professional staff and the general public,” according to a Community Development Department press release inviting people to the 7 p.m. meeting at the John A. Volpe National Transportation Systems Center, 55 Broadway, Kendall Square.

Meanwhile, much of the rooftop garden between 3, 4 and 5 Cambridge Center was fenced off Oct. 3 for construction — more than a month after the date allowed by the authority.

The construction will add a two-story building that connects Google offices in two of those buildings. (A four-story connector is being built to bridge other Cambridge Center offices, without affecting the garden.) Kevin Sheehan, a senior project manager with developer and landlord Boston Properties, said the two-story building and private garden space will take away about 42 percent of the garden the public has been able to use since its opening in 1984. The specs, as provided by Sheehan:

After construction of the project is complete, 25,340 square feet of publicly dedicated open space will remain on the roof garden. The original area of the roof garden was 43,487 square feet, so approximately 58 percent of the original area will remain.

During construction, there will be slightly less space available to the public, since the construction “staging” area needs to be bigger to allow room for work, Sheehan confirmed.

In exchange for the right to take away 42 percent of the public park, which has long been lauded as one of the region’s hidden treasures, Boston Properties promised in March to extend public access to what remains to Aug. 5, 2050, from the previous expiration date of Aug. 5, 2022; contribute $2 million to the so-called “porkchop” park between Broadway, Binney Street and Galileo Galilei Way; give $250,000 to improve the sculpture park at Third Street, Broadway and Main Street, known as Point Park; and add events and programming to the plaza on Main Street in front of the Marriott Hotel.

For information on the Thursday meeting, call (617) 349-4751 or (617) 349-4632.