Editing Red Line (MBTA) (section)

{{short description|Rapid transit line in Massachusetts, US}}
{{Infobox rail line
| name                            = Red Line
| color                           = {{rcr|MBTA|Red}}
| image                           = Charles MGH Northbound MBTA Red Line Platform (1), January 2025.jpg
| image_width                     = 300px
| caption                         = A northbound Red Line train at [[Charles/MGH station]] in 2025
| type                            = [[Rapid transit]]
| system                          = [[MBTA subway]]
| locale                          = [[Boston]], [[Cambridge, Massachusetts|Cambridge]], [[Somerville, Massachusetts|Somerville]], [[Braintree, Massachusetts|Braintree]] and [[Quincy, Massachusetts]]
| start                           = {{bts|Alewife}} (north)
| end                             = {{bts|Ashmont}} and {{bts|Braintree}} (south)
| stations                        = 22
| linelength                      = {{cvt|11.5|mi|km}} Alewife–Ashmont<br />{{cvt|17.5|mi|km}} Alewife–Braintree<br />{{cvt|22.5|mi|km}} total
| routes                          = 2
| daily_ridership                 = 119,000 (2023)<ref>{{cite web |url=https://cdn.mbta.com/sites/default/files/2024-08/7.%20History%20of%20Funding%20Updated%20V16%208.21.24.pdf |date=August 22, 2024 |first1=Mary Ann |last1=O'Hara |first2=Pat |last2=Turners |publisher=Massachusetts Bay Transportation Authority |page=2 |title=History of Funding Update}}</ref>
| open                            = March 23, 1912
| owner                           = [[Massachusetts Bay Transportation Authority]]
| stock                           = 1500, 1600, 1700, 1800, 1900-series
| gauge                           = {{track gauge|ussg|allk=on}}
| electrification                 = {{600 V DC|conductor=third rail}}
| map                             = {{switcher
|{{maplink-road|from=Red Line (MBTA).map}}
|Show interactive map
|{{MBTA Red Line|inline=1}}
|Show route diagram map
}}
| map_state                       = 
}}

The '''Red Line''' is a [[rapid transit]] line operated by the [[Massachusetts Bay Transportation Authority]] (MBTA) as part of the [[MBTA subway]] system. The line runs south and east underground from [[Alewife station]] in [[North Cambridge, Massachusetts|North Cambridge]] through [[Somerville, Massachusetts|Somerville]] and [[Cambridge, Massachusetts|Cambridge]], surfacing to cross the [[Longfellow Bridge]] then returning to tunnels under [[Downtown Boston]]. It continues underground through [[South Boston]], splitting into two branches on the surface at [[JFK/UMass station]]. The Ashmont branch runs southwest through [[Dorchester, Boston|Dorchester]] to [[Ashmont station]], where the connecting [[light rail]] [[Mattapan Line]] (shown as part of the Red Line on maps, but operated separately) continues to [[Mattapan station]]. The Braintree branch runs southeast through [[Quincy, Massachusetts|Quincy]] and [[Braintree, Massachusetts|Braintree]] to [[Braintree station (MBTA)|Braintree station]].

The Red Line operates during normal MBTA service hours (all times except late nights) with six-car trains. The 218-car active fleet consists of three orders of cars built in 1969–70, 1987–89, and 1993–94. A 252-car order from [[CRRC]] is being built from 2019 to 2024. The Red Line is fully [[Grade separation|grade-separated]]; trains are driven by operators with [[automatic train control]] for safety. Cabot Yard in South Boston is used for heavy maintenance and storage; yards at Alewife, Ashmont, and Braintree are also used for storage. All 22 Red Line stations are fully [[MBTA accessibility|accessible]]. Averaging 119,000 weekday passengers in 2023, the Red Line has the highest ridership of the MBTA subway lines.

The [[Boston Elevated Railway]] opened its Cambridge tunnel between {{bts|Harvard}} and {{bts|Park Street}} in 1912. It was extended south as the Dorchester Tunnel to Washington (now {{bts|Downtown Crossing}}) in 1915, {{bts|South Station|Red}} in 1916, {{bts|Broadway}} in 1917, and {{bts|Andrew}} in 1918. The Dorchester extension added three stops to {{bts|Fields Corner}} in 1927 and two more stops to Ashmont in 1928. Charles (now {{bts|Charles/MGH}}) was added as an [[infill station]] in 1932. The newly formed MBTA assigned colors to its subway lines in 1965, with the Cambridge–Dorchester line becoming the Red Line. The MBTA added the three-station South Shore Line to {{bts|Quincy Center}} in 1971; it was extended to Braintree in 1980, with {{bts|Quincy Adams}} added as an infill in 1983. The Red Line Northwest Extension, originally planned to run to [[Arlington Heights, Massachusetts|Arlington Heights]] or [[Massachusetts Route 128|Route 128]], opened to {{bts|Davis}} in 1984 and Alewife in 1985.