Project Owner

Chicago Department of Transportation (CDOT)



Services Provided

Phase I/II Design Services


Chicago, IL

Year of Construction


Webster Ave over the Chicago River


The project on Webster Ave over the Chicago River involved the comprehensive rehabilitation of an existing double-leaf, trunnion bascule bridge. HBM Engineering Group, LLC was a subconsultant to WSP, and they worked in collaboration with the Chicago Department of Transportation (CDOT) to execute the project. The primary objective of the project was to enhance the structural integrity, safety, and overall condition of the bridge to extend its service life and ensure it meets modern engineering standards.

Existing Structure Overview:

  • The existing bridge had a total length of 291 feet and 3 inches.
  • The overall deck width was 60 feet.
  • It carried one eastbound lane, one westbound lane, one westbound turn lane, and two sidewalks over the North Branch of the Chicago River.
  • The movable span of the bridge featured a superstructure consisting of a 5-inch steel grid deck supported by rolled steel stringers, built-up steel floorbeams, and two half-through trusses.
  • The substructure of the existing bridge consisted of reinforced concrete piers and abutments supported by timber piles.


HBM’s Scope:

  • In-depth review of existing documents, field inspection, and preparation of field notes.
  • Preparation of a Bridge Condition Report (BCR) to assess the state of the bridge.
  • Preparation of Type, Size, and Location (TS&L) Plans to provide a detailed understanding of the project’s parameters.
  • Review of rating calculations for existing stringers and floor beams to determine their load-bearing capacity.
  • Prepare detailed final plans for the repairs and rehabilitation required.
Webster Ave over the Chicago River_HBM

Scope of Work: The scope of work for the bridge rehabilitation encompassed several key elements:

  • Deck and Sidewalk Replacement: Removal and replacement of the deck and sidewalks in both the movable and fixed spans of the bridge.

  • Expansion Joint Construction: Construction of expansion joints between the fixed and movable spans and at the center break to accommodate movement and prevent damage.

  • Stringer and Floorbeam Replacement: The removal and replacement of all stringers in the movable span and select stringers in the fixed spans, along with all floorbeams in the movable span.

  • Truss and Bracing Repairs: Repair and strengthening of the main truss and bottom lateral bracing in the movable span to restore the original design capacity.

  • Steel Structure Maintenance: Cleaning and painting of steel superstructure members for preservation.

  • Railing Replacement: Removal and replacement of steel and concrete railings for improved safety.

  • Live Load Bearings: Repair and adjustment of live load bearings to ensure proper functionality.

  • Bridge Balancing: Performing bridge balancing to ensure even weight distribution and proper operation of the bascule bridge.

  • Concrete Repairs: Structural repair of concrete and epoxy crack injection at various locations, including counterweight pits, river piers, and abutment stems.

  • Pier Protection: Replacement of damaged dolphins and fender system with a new approved pier protection system.

  • Retaining Wall Repairs: Repair of damaged areas in northeast and southeast retaining walls.

  • Bearing Pedestal Replacement: Removal of existing bearing pedestals, repair of surrounding concrete, and cleaning of the bearing area to accommodate new bearings.

HBM's contribution to the Webster Ave bridge rehabilitation project is a testament to the firm's dedication to excellence, technical prowess, and commitment to ensuring the longevity and safety of critical infrastructure. HBM's capabilities in addressing complex challenges in civil engineering make it a valuable partner in delivering high-quality and sustainable infrastructure solutions.