Editing Red Line (MBTA) (section)

===Dorchester Tunnel and extension===
[[File:Southerly view of easterly side of Columbia Station, August 1927.jpg|thumb|left|Columbia station (later JFK/UMass) on the Dorchester extension under construction in 1927]]
The '''Dorchester Tunnel''' to [[Downtown Crossing (MBTA station)|Washington Street]] and South Station Under opened on April 4, 1915 and December 3, 1916, with transfers to the [[Washington Street Tunnel (Boston)|Washington Street Tunnel]] and [[Atlantic Avenue Elevated]], respectively.  Further extensions opened to [[Broadway (MBTA station)|Broadway]] on December 15, 1917 and [[Andrew (MBTA station)|Andrew]] on June 29, 1918, both [[prepayment station]]s for streetcar transfer.  The Broadway station included [[Broadway (MBTA station)#Streetcar tunnel|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 (architecture)|mezzanine]].

Next came the '''Dorchester extension''' (now the '''Ashmont branch'''), following a [[Right-of-way (railroad)|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 (Boston)|Harrison Square]] with the [[Dorchester and Milton Branch Railroad]], running from the Old Colony at [[Neponset, Boston|Neponset]], west to what is now [[Mattapan (MBTA station)|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 of the construction of the BERy's Dorchester extension.<ref>[http://world.nycsubway.org/us/boston/red.html End of service on Old Colony's Shawmut Branch]</ref>

The BERy opened the first phase of the Dorchester extension, to [[Fields Corner (MBTA station)|Fields Corner station]], on November 5, 1927, south from [[Andrew (MBTA station)|Andrew]], then southeast to the surface and along the west side of the Old Colony mainline in a depressed right-of-way. [[JFK/UMass (MBTA station)|Columbia]] and [[Savin Hill (MBTA station)|Savin Hill]] stations were built on the surface at the sites of former Old Colony stations.  The remainder of the extension opened to [[Ashmont (MBTA station)|Ashmont]] and [[Codman Yard]] on September 1, 1928, and included [[Shawmut (MBTA station)|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 [[Mattapan Line|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]].

On January 13, 1961, the MTA began operating "[[Skip-stop|modified express service]]" on the line during the morning rush hour, following the introduction of similar service on the Forest Hills–Everett line the month before. Every other train bypassed Shawmut, Savin Hill, Columbia, and Charles stations.<ref>{{cite news |url=https://www.newspapers.com/article/the-boston-globe/137738689/ |title=MTA Boosts Service For New Year's Eve |newspaper=The Boston Globe |date=December 29, 1960 |page=8 |via=Newspapers.com}}</ref> This was discontinued in September 1961 to reduce wait times at the skipped stations, most of which were outdoors.<ref>{{cite news |url=https://www.newspapers.com/article/the-boston-globe/137738740/ |title=M.T.A. Dropping Morning Express |newspaper=The Boston Globe |date=September 27, 1961 |page=10 |via=Newspapers.com}}</ref>

Charles was renamed Charles/MGH in December 1973, and Kendall was renamed Kendall/MIT on August 7, 1978.<ref name="netransit" /> 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.<ref>{{cite news |url=https://www.newspapers.com/clip/38328446/the_boston_globe/ |title=Public Hearing Notice  |date=January 28, 1981 |author=Massachusetts Bay Transportation Authority |newspaper=Boston Globe |page=65 |via=Newspapers.com}}{{open access}}</ref> The closure was cancelled, though the lines were closed from June 20, 1981, to January 16, 1982, for track replacement and tunnel repairs.<ref name=netransit />