Lechmere Viaduct

Lechmere Viaduct
Lechmere Viaduct, viewed looking southward from East Cambridge (Charles River Dam is visible through Viaduct arches)
Coordinates	42°22′05″N 71°04′13″W / 42.36803°N 71.07035°W / 42.36803; -71.07035Coordinates: 42°22′05″N 71°04′13″W / 42.36803°N 71.07035°W / 42.36803; -71.07035
Carries	Light rail
Crosses	Charles River
Locale	Boston, Massachusetts to Cambridge, Massachusetts
Characteristics
Design	Arch bridge (reinforced concrete and structural steel)
Total length	1,700 feet (520 m)
No. of spans	12
History
Construction begin	June 20, 1907
Opened	June 1, 1912

The Lechmere Viaduct is a concrete arch bridge connecting the West End neighborhood of Boston to East Cambridge, Massachusetts. Opened in 1912, the viaduct carries the MBTA's Green Line over the Charles River. It is adjacent to the Charles River Dam Bridge, but structurally separate.

When the Tremont Street Subway fully opened in 1898, surface cars entering the subway from East Cambridge had to cross Craigie's Bridge and proceed on surface streets to the Canal Street Incline. The trip from Lechmere Point over the bridge was slow and prone to delays. On June 20, 1907, construction began on one mile of elevated track connecting the Canal Street Incline to East Cambridge. The project's centerpiece was the 1,700-foot (520 m) arched viaduct crossing the Charles River, with 12 spans including a short drawbridge section.

Other sections of elevated track included the Causeway Street Elevated on the Boston side of the river, and the Lechmere Elevated on the East Cambridge side. The first streetcars crossed the bridge in revenue service on June 1, 1912, shortening the ten-minute trip from Lechmere Square to the subway to just three minutes. The building of the massive structure was done entirely by the Boston Elevated Railway, without use of subcontractors.

The BERy opened Lechmere station on July 10, 1922, as a transfer point between the Cambridge streetcars and the subway cars. This prevented traffic delays affecting the surface cars from propagating into the subway, and allowed the underground service to use three-car trains, which were too long for safe street-running.

On August 20, 1955, Science Park station opened as an infill station on the viaduct over Leverett Circle. It serves the Boston Museum of Science and the West End.