of the construction of the BERy's Dorchester extension. The BERy opened the first phase of the Dorchester extension, to Fields Corner station, on November 5, 1927, south from Andrew, then southeast to the surface and along the west side of the Old Colony mainline in a depressed right-of-way. Columbia and Savin Hill stations were built on the surface at the sites of former Old Colony stations. The remainder of the extension opened to Ashmont and Codman Yard on September 1, 1928, and included Shawmut station, where there had been a surface Old Colony station, but where the new rapid transit station was placed underground. The first phase of the Ashmont–Mattapan High Speed Line opened on August 26, 1929, using the rest of the Shawmut Branch right-of-way, including Cedar Grove station, and part of the old Dorchester and Milton Branch. Charles was renamed Charles/MGH in December 1973, and Kendall was renamed Kendall/MIT on August 7, 1978. In January 1981, the MBTA proposed to close the Ashmont branch on Sundays – and the Mattapan Line at all times – beginning that March due to severe budget issues. The closure was cancelled, though the lines were closed from June 20, 1981, to January 16, 1982, for track replacement and tunnel repairs. MBTA era and branding The line was sometimes referred to as the Cambridge–Dorchester line and the Cambridge–Dorchester subway. It was marked on maps as "Route 1". After taking over operations in August 1964, the MBTA began rebranding many elements of Boston's public transportation network. Colors were assigned to the rail lines on August 26, 1965 as part of a wider modernization developed by Cambridge Seven Associates, with the Cambridge–Dorchester line becoming the Red Line. Peter Chermayeff claims to have assigned red to the line because of Harvard's association with crimson. In 1968, letters were assigned to the south branches, "A" for Quincy (planned to extend to South Braintree) and "C" for Ashmont. "B" was probably reserved for a planned branch from Braintree to Brockton. As new rollsigns were made, this lettering was phased out. In 1994, new electronic signs included a different labeling, "A" for Ashmont, "B" for Braintree, and "C" for Alewife. South Shore line On July 28, 1965, the MBTA signed an agreement with the New Haven Railroad to purchase of the former Old Colony mainline from Fort Point Channel to South Braintree in order to construct a new rapid