CONTRACTS I-17-4676 and I-18-4694

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The scope of work of this project included Phase II design engineering for the preparation of the plans, specifications and estimates (PS&E), for the construction of the proposed Elgin-O’Hare Western Access (I-490) Bridge construction and building demolition at I-90.

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Garza Karhoff Engineering (GKE) served as Structural Engineer for the design and construction plan development of the integral abutments for the two new two-span continuous bridges (BN 1681 and BN 1682) that carry I-490 Ramps X3 and X4 over the Jane Addams Tollway (I-90). The proposed bridges consist of a typical eight-inch composite concrete deck with 63-inch precast prestressed concrete (PPC) beams supported on integral abutments and multi-column pier supported on pile foundations, accompanied by two new mechanically stabilize earth (MSE) walls and two new cast-in-place (CIP) L-type retaining walls.

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GKE’s civil engineers assisted the design team with preparing the contract plans for proposed roadway plans and profiles, removal plans, pavement joint and elevation plans, environmental soil classification plans, roadway details, super-elevation diagrams, alignment & ties, fence plans, grading plans, maintenance of traffic and suggested staging, typical sections, and an estimate of cost while utilizing all applicable Illinois Tollway and IDOT standards.

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Key Issues Faced: The accelerated construction schedule required for construction to begin before completion of the full interchange design.

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Innovative Solution: Two bridges and retaining walls were packaged into a separate accelerated contract and all available staff worked on a fast-tracked schedule to ensure that the accelerated design was delivered on time and on budget.