Lake Street over the South Branch of the Chicago River-converted

Description of Project

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.

Description of Scope of Work:

HBM prepared emergency repair plans for the Lake Street Bridge over the South Branch of the Chicago River (SN 016-6029). These repair plans were developed for bottom chord and diagonal truss members. Bottom chord members were stiffened with additional top and bottom flange angles as required. Additional repairs included the removal and replacement of splice plates, batten plates, filler plates and lacing bars.

The HBM scope of services included the Phase II and Phase III engineering services as described below:

• Structural Final Plans and quantity calculations
• Phase III construction support
• Quality Assurance / Quality Control (QA/QC)