Community Path Pedestrian Viaduct

Steere Engineering provided bridge engineering and overall Design Package management for the design and construction of the Community Path Pedestrian Viaduct as part of the 4.3-mile Green Line Light Rail Extension Project (GLX).  The Community Path Pedestrian Viaduct is a 1200-foot long, 11-span pedestrian bridge that traverses an elevated light rail viaduct and serves to connect the reconstructed Lechmere Station to the City of Somerville.

The elevated pedestrian viaduct consists of 10 approach spans comprised of straight and curved twin plate girders and a prefabricated steel tubular truss main span supported on hammerhead substructures on drilled shafts.  The Community Path alignment and profile were dictated by numerous site constraints that resulted in several curved spans and a main span that is approximately 60 feet above grade.    

Superstructure design was primarily performed using MDX and complicated by the Design-Builder’s desire to re-use existing plates available as part of the GLX contract.  Due to revisions to the span arrangement from a previous design, re-use of the available plates required that nearly every span have two splices (shop or field).  Substructure geometry and design was complicated by the presence of a number of existing utilities and structures that required several hammerheads to be asymmetric.

Location: Cambridge & Somerville, MA

Owner: Massachusetts Bay Transportation Authority (MBTA)

Timeline: Design Completed in 2019; Construction Completed in 2023