Lake Street over the South Branch of the Chicago River — Major Bridges Biennial Fracture Critical Bridge Inspections

Project Overview

Description

HBM Engineering Group, LLC, demonstrated a swift and effective response in executing emergency repairs for the Lake Street Bridge, showcasing a commitment to structural excellence and the safety of critical urban infrastructure. The existing structure consists of a two-level double-leaf trunnion bascule bridge over the South Branch of the Chicago River. The upper level carries two CTA railroad tracks and the lower level carries the Lake Street roadway and sidewalks. The bridge consists of a west fixed span over the counterweight pit, two bascule leaves comprising the main river span, and an east fixed span over the counterweight pit. The structure has an overall length of 331'-3" (centerline-to-centerline anchor columns; 57'-0" / 217'-3" / 57'-0" spans). The overall out-to-out deck width is 70'-0". The movable span superstructure consists of concrete-filled metal grating supported on steel stringers, built-up transverse floor beams and built-up truss members. The approach span superstructure consists of a reinforced concrete deck on steel stringers and built-up transverse floorbeams and cross girders. The substructure consists of reinforced concrete piers and abutments with counterweight pits.

HBM's Scope

Scope of Work

• ›Emergency repair plans for crucial structural elements — specifically targeting bottom chord and diagonal truss members
• ›Stiffening measures incorporating additional top and bottom flange angles
• ›Removal and replacement of splice plates, batten plates, filler plates, and lacing bars
• ›Structural inspection and load assessment
• ›Coordination with CTA rail operations and Lake Street vehicular/pedestrian traffic