CATEGORY: C - Structural Systems

CLIENT/OWNER: Forest Preserve District of DuPage County

SUBMITTING FIRM: Lochner

KEY PARTICIPANTS: H.W. Lochner, Inc., Millennia Professional Services, Ltd., Huff & Huff Inc., Geo Services, Inc., Engineering Resource Associates, Inc., Alliance Contractors, Inc., Bach Ornamental and Structural Steel, Inc., Forest Preserve District of DuPage County

DESCRIPTION: The Hidden Lake Bridge Restoration and Rehabilitation project preserves the historic nature and restores functionality of the only known example in the region of a cast and wrought iron bowstring truss bridge. A combination of historic materials and traditional metal working techniques were combined with innovative engineering design and modern construction practices to restore this 150-year-old structure. Detailed research and analysis was required to ensure that new structural elements such as the steel floor beam system were compatible with the existing structure, that the historic characteristics of the bridge were maintained, and modern service vehicle loading could be accommodated. Disassembling the truss and performing specialty fabrication in the controlled off-site shop maximized the safety of the construction team, ensured quality workmanship, eliminated any construction staging that involved forest preserve users and helped maintain schedule constraints.