Condo tower approved for Boylston Street

An artist’s depiction of the proposed Boylston Street condo building that won city approval. To the left is the One Dalton tower, which is now under construction. –Weiner Ventures

The Back Bay’s “high spine’’ could soon get another spike.

Developers planning a 484-foot condominium tower on Boylston Street above the Massachusetts Turnpike hope to start work on the project later this year, after winning a key approval from the Boston Planning & Development Agency Thursday night.

Adam Weiner of Weiner Ventures said he’s aiming for a fall groundbreaking on a deck above the Pike that would support the tower, which would rise along Boylston between Massachusetts Avenue and Dalton Street. It would take a year to build the deck above the busy highway, then two more for work on the tower itself.