In May 1924, the state legislature directed the Metropolitan District Commission to plan an expanded rapid transit system in Boston, including an extension of the Boylston street Subway under Governors Square. The report, released in December 1926, called for the existing streetcar tunnels in Boston to be reorganized into two rapid transit lines with high-floor rolling stock. One line was to run from Lechmere through the existing Tremont Street subway, parallel the New Haven Railroad tracks towards Providence using tunnels and an embankment as far as Massachusetts Avenue, then run along the surface on Huntington Avenue to Francis Street (Brigham Circle). The extension would have new stations at Pleasant Street, Back Bay station, West Newton Street, and Massachusetts Avenue, plus consolidated surface stops at the and the . Streetcar lines on Tremont Street and Huntington Avenue would connect with rapid transit trains at a surface-level transfer station at Brigham Circle. Future extension of the tunnel to Brookline Village was considered.