Project Owner

Chicago Department of Transportation (CDOT)


Milburn Demolition (Milburn)

Services Provided

Structural Engineering
Demolition Analysis and Procedure


Chicago, IL

Year of Demolition


Harrison Street Viaduct West of the Chicago River Demolition Procedure

Milburn Demolition, in collaboration with HBM Engineering Group, LLC, is undertaking the demolition of the Harrison Street Viaduct, located west of the Chicago River in Chicago, Illinois. The project is part of CDOT Project No. E-1-519 and involves a phased removal of the viaduct structure.

The structure consists of 22 spans with an overall length of approximately 780’-6” and an out-to-out deck width of 66’-0”. The bridge superstructure consists of a reinforced concrete deck (8” thickness plus 2” asphalt overlay) on rolled and built-up steel girder. The bridge substructure consists of a reinforced concrete west abutment and built-up steel bent caps and columns. Concrete encasement is present at portions of the built-up girders, bent caps and columns.

Project Phases:

  1. Phase 1 Removal (Stage I, II, and a portion of III):

    • Spans 1-5, a portion of the west abutment, and portions of Bents 1-4 are targeted.
    • Deck, wearing surface, girders, and bent caps will be demolished and removed.
    • Safety measures include OSHA compliance, fall protection, and adherence to Milburn safety requirements.
  2. Phase 2 Removal (Stage III, IV, V, VI):

    • Spans 6-12 and portions of Bents 5-11 are scheduled for removal.
    • Similar components, such as deck, superstructure, girders, and bent caps, will be demolished.
    • Safety measures and equipment specifications continue to be implemented.
  3. Phase 3 Removal (Stage VII-XI):

    • Spans 13-22 and portions of Bents 12-22 constitute the focus of this phase.
    • The demolition plan includes the removal of deck, superstructure, girders, and bent caps.
    • Safety protocols and equipment specifications are reiterated.


HBM’s Scope:

  • Structural Engineering
  • Demolition Analysis and Procedure

Demolition Procedure Highlights:

  • Adherence to OSHA and Milburn safety requirements.
  • Fall protection at leading edges.
  • Use of cranes within specified wind speed limits.
  • Environmentally conscious disposal of concrete and steel at legal recycling facilities.
  • Special precautions for steel treated as lead paint.
  • Protection measures for adjacent structures, utilities, and infrastructure.
  • Facade protection for the north building, including marble base preservation.
  • Specific procedures for asphalt overlay, sidewalk, deck, girder, and abutment removal.
  • Rigorous clean-up process, including loading debris into containers for disposals.


A non-linear finite element analysis (FEA) using CSI Bridge software was conducted:

Elements Connectivity and Boundary Conditions:

  • Steel elements (columns, girders, and stringers) modeled with frame elements.
  • Concrete deck modeled with shell elements.
  • Bridge deck connected to steel stringers with fully rigid body constraints.
  • Stringers assumed discontinuous between bent caps, connected to bents using 2-Joint Links.
  • Bent caps connected to bent columns with fixed connections.

Deck Analysis:

  • 2D plane model at the centerline of the concrete slab.
  • Dead load staged for current condition and during the removal process.
  • Stringers analyzed with 2-Joint Links and moment releases.
  • Deck analyzed for live load application during crane movement and removal stages.
  • Hand calculations were performed using Mathcad.

The phased demolition of the Harrison Street Viaduct is meticulously planned, emphasizing safety, environmental responsibility, and systematic removal of structural elements. The project aims to ensure the efficient and secure removal of the viaduct while minimizing impacts on surrounding infrastructure and the environment.