Project Owner

Chicago Department of Transportation (CDOT)



Services Provided

Phase II Design Services


Chicago, IL

Year of Repair


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


The existing structure consists 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:

HBM undertook emergency repair plans for crucial structural elements, specifically targeting bottom chord and diagonal truss members. Stiffening measures were implemented, incorporating additional top and bottom flange angles. The repair strategy also encompassed the removal and replacement of splice plates, batten plates, filler plates, and lacing bars.

Key Repairs:

  1. Bottom Chord and Diagonal Truss Members: Strengthened through the addition of top and bottom flange angles.
  2. Splice Plates, Batten Plates, Filler Plates, and Lacing Bars: Methodically removed and replaced to enhance structural integrity.

Phases of Work:

  1. Phase II – Structural Final Plans:

    • Development of comprehensive plans detailing repair strategies.
    • Quantity calculations for precise material requirements.
  2. Phase III – Construction Support:

    • Ongoing support during the implementation of repair plans.
    • Quality Assurance/Quality Control (QA/QC) measures to ensure adherence to engineering standards.

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.