Ashmont–Mattapan High-Speed Line

ASHMONT–MATTAPAN HIGH SPEED LINE
PCC Streetcar on the Ashmont-Mattapan High Speed Line
Overview
Type	Light rail
Locale	Boston, Massachusetts (Dorchester to Mattapan) via Milton, Massachusetts
Termini	Ashmont Mattapan
Stations	8
Services	1
Daily ridership	4,637
Operation
Opened	August 26, 1929 (Ashmont to Milton) December 21, 1929 (Milton to Mattapan)
Owner	MBTA
Operator(s)	MBTA
Character	Private right-of-way (largely grade-separated)
Rolling stock	PCC streetcar
Technical
Line length	2.54 miles (4.09 km)
Track gauge	4 ft 8 1⁄2 in (1,435 mm)
Minimum radius	43 ft (13.106 m)
Electrification	600V overhead lines
Route map Red Line to Alewife 0 km 0 mi Ashmont  Red Line  0.35 km 0.22 mi Cedar Grove 0.95 km 0.59 mi Butler Neponset River 1.25 km 0.78 mi Milton Central Ave. 1.54 km 0.96 mi Central Avenue 1.98 km 1.23 mi Valley Road Capen St. 2.31 km 1.44 mi Capen Street Neponset River 2.54 km 1.58 mi Mattapan Mattapan Yard/Loop This diagram:

The Ashmont–Mattapan High Speed Line, also known as the "M-Line", is a partially grade-separated light rail line which forms part of the MBTA's Red Line rapid transit line. The line, which runs through Boston and Milton, Massachusetts, opened on August 26, 1929, as a conversion of a former commuter rail line and exclusively uses historic PCC streetcars for rolling stock. Passengers must transfer at Ashmont to access the rest of the Red Line, which uses heavy rail metro rolling stock.

The term "high-speed line" is a historic designation, distinguishing the exclusive and largely grade-separated right-of-way at a time when most trolleys ran down streets shared with automobiles. The 2.6-mile (4.2 km) route is used only by streetcars and has just two public grade crossings. All stations have low platforms, but all except Valley Road have been retrofitted with wheelchair lifts or wooden ramps for handicapped accessibility.

The Ashmont–Mattapan Line begins and ends within the city of Boston, but most of the southern half of its route is in the northern part of the neighboring town of Milton. It follows the right-of-way of two former Old Colony Railroad branches which had commuter rail service until the 1920s. Much of the route parallels the Neponset River, crossing it twice. The right-of-way is owned by the MBTA and has only two at-grade crossings on its 2.6-mile (4.2 km) route.

Between Cedar Grove and Butler stations, the line runs through the center of the Cedar Grove Cemetery.

The Dorchester and Milton Branch Railroad opened in December 1847 from Neponset on the Old Colony main line to Mattapan station in Dorchester via Milton Mills (later Milton Lower Mills, then simply Milton). The line was immediately leased by the Old Colony as its Milton Branch (Neponset Branch). The Old Colony built the Shawmut Branch Railroad from Harrison Square on the main line to Milton Lower Mills via Peabody Square in 1872. Most Mattapan passenger service switched to use the new branch east of Milton, as it ran through dense urban neighborhoods rather than swamps. The Old Colony Railroad and its branches were acquired by the New York, New Haven and Hartford Railroad in 1893.