to Boston, was delayed by a dispute over the number of intermediate stations to be built along the new line. Cambridge residents, led by Mayor Wardwell, wanted at least five stations built along the line, while suburbanites interested in faster through travel argued for only a single intermediate station, at Central Square. The contending groups finally compromised on two intermediate stations, at Central and Kendall Squares, allowing construction to start in 1909. The section from Harvard (and new maintenance facilities at Eliot Yard) to Park Street was opened by the Boston Elevated Railway (BERy) on March 23, 1912. At Harvard, a prepayment station provided easy transfer to streetcars routed through what is now the Harvard bus tunnel. From Harvard, the Cambridge tunnel traveled beneath Massachusetts Avenue to Central Square station. It then continued under Mass. Ave until Main Street, which it followed to reach Kendall station. The underground line then rose onto the Longfellow Bridge, using a central right-of-way which had been reserved during the bridge's 1900–1906 construction. On the Boston side, the line briefly became an elevated railway, as vehicle lanes descended beneath it to Charles Circle; the tracks then immediately entered a tunnel beneath Beacon Hill, leading to new lower-level platforms at Park Street Under. Charles Station (now Charles/MGH) was added above the traffic circle in 1932. Dorchester Tunnel and extension The Dorchester Tunnel to Washington Street and South Station Under opened on April 4, 1915 and December 3, 1916, with transfers to the Washington Street Tunnel and Atlantic Avenue Elevated, respectively. Further extensions opened to Broadway on December 15, 1917 and Andrew on June 29, 1918, both prepayment stations for streetcar transfer. The Broadway station included an upper level with its own tunnel for streetcars, which was soon abandoned in 1919 due to most lines being truncated to Andrew. The upper level at Broadway was later incorporated into the mezzanine. Next came the Dorchester extension (now the Ashmont branch), following a rail right-of-way created in 1870 by the Shawmut Branch Railroad. In 1872, the right-of-way was acquired by the Old Colony Railroad to connect their main line at Harrison Square with the Dorchester and Milton Branch Railroad, running from the Old Colony at Neponset, west to what is now Mattapan station. The New York, New Haven and Hartford Railroad succeeded the Old Colony in operating the branch, but passenger service ceased on September 4, 1926, in anticipation