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Lechmere Viaduct

From Alfawiki
Lechmere Viaduct
Company typeInfrastructure
IndustryTransportation
Founded1912
Headquarters
Boston and Cambridge, Massachusetts
,
United States
ProductsBridge carrying MBTA Green Line light rail

The Lechmere Viaduct is a concrete arch bridge that connects Boston's West End neighborhood to East Cambridge, Massachusetts. Since its inauguration in 1912, it has carried the MBTA's Green Line across the Charles River. Although located next to the Charles River Dam Bridge, the viaduct is an independent structure.

Construction

Prior to the viaduct's existence, surface streetcars from East Cambridge crossed Craigie's Bridge and operated on street-level tracks to reach the Canal Street incline, resulting in slow and congested trips. On June 20, 1907, work commenced on an elevated track approximately one mile long, designed to connect the Canal Street incline directly to East Cambridge. The centerpiece of this project was a 12-span viaduct stretching over the Charles River.[1] This included ten arches, a bascule drawbridge at the third span over the river channel, and a girder span at the twelfth span crossing the Gilmore Bridge approach.[2]

The viaduct was integrated with the Causeway Street Elevated in Boston and featured a short steel elevated section descending toward Lechmere Square in East Cambridge. Revenue service for streetcars began on June 1, 1912, cutting travel time between Lechmere Square and the subway from ten minutes down to three.[3][4] The Boston Elevated Railway (BERy) managed construction entirely in-house without subcontracting.[3]

Lechmere station opened on July 10, 1922, serving as a transfer hub between Cambridge streetcars and subway trains. This arrangement prevented surface traffic delays from impacting subway schedules and allowed longer three-car trains to operate underground.[3] In 1935, there was a proposal to widen the viaduct into a four-lane expressway as part of an extension of the Mohawk Trail, with transit services diverted to a parallel subway line.[5]

On August 20, 1955, the MTA inaugurated Science Park station, situated on the steel approach span above Leverett Circle. This station provided access to both the Boston Museum of Science and the West End neighborhood.[3]

Service disruptions and rehabilitation

Service over the viaduct was halted on June 25, 2004, due to removal of the Causeway Street Elevated and consolidation of platforms at North Station into a new underground "superstation." After this change, only the Lechmere Viaduct and Lechmere Elevated remained as Boston’s last elevated rail lines. A new portal off Martha Road and a concrete bridge connecting to the viaduct south of Science Park station were constructed during this period. Service resumed to Lechmere on November 12, 2005.[6] The incline transitioning from the tunnel built in 2005 up to the viaduct represents the steepest grade within the MBTA subway system.[7] The viaduct was closed again between April 30 and November 4, 2011, for upgrades at Science Park station that included installation of accessible platforms and elevators.[6]

The Green Line Extension initiative resulted in removal of the northern segment of the Lechmere Elevated. It was replaced with a new elevated structure located east of Route 28 along with a newly constructed Lechmere station. The viaduct was closed starting May 24, 2020, with service truncated back to North Station; reopening was anticipated in April 2021.[8] Demolition of the northern steel section commenced on June 6, 2020.Cite error: The opening <ref> tag is malformed or has a bad name Only the steel portion north of Gilmore Bridge was replaced; meanwhile, the primary concrete spans were rehabilitated to support Green Line Extension operations as well as future deployment of Type 10 vehicles.Cite error: The opening <ref> tag is malformed or has a bad name By July 2021, rehabilitation efforts were approximately 83% complete, with track installation, signal upgrades, power systems work nearing conclusion alongside ongoing concrete repairs.[2] Substantial completion was reached on March 16, 2022.Cite error: The opening <ref> tag is malformed or has a bad name

At its closure in 2020, only the E branch utilized the viaduct while other branches terminated downtown. Following completion of the extension, both D and E branches operate over it: E branch extending to , and D branch heading toward .[9] Service recommenced on March 21, 2022 concurrent with opening of the Union Square Branch.Cite error: The opening <ref> tag is malformed or has a bad name Between August 22 and September 18, 2022, service was suspended for replacement of wiring on the viaduct aimed at boosting speeds from to , along with final integration work for the Medford Branch.[10] However, this upgrade did not achieve expected speed enhancements, leading to an extended multi-year slow zone restricting speeds to .[11]

External links

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named inspect
  2. ↑ 2.0 2.1 Cite error: Invalid <ref> tag; no text was provided for refs named GLTjuly2021
  3. ↑ 3.0 3.1 3.2 3.3 Cite error: Invalid <ref> tag; no text was provided for refs named century
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  6. ↑ 6.0 6.1 Cite error: Invalid <ref> tag; no text was provided for refs named netransit
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named BostonGlobe2005
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named mbta2020-5-15
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named 2021branches
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named nov22
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named jan23
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