Technical Description:
• 19'-6" x 10’-6” x 95' CON/SPAN
® B-Series Bridge System
• 4’ x 2’ EXPRESS
® Foundations
• 3’ x 2’ EXPRESS® Foundations
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For many years, the City of Des Moines, Iowa had envisioned a pedestrian underpass under Fleur Drive. Not only would an underpass eliminate safety concerns with the current at grade crossing, it would also enhance connectivity to nearby popular attractions, including Gray's Lake, Lauridsen Amphitheater and Arie Den Boer Arboretum. Thanks to a generous donation, the city was finally able to fully fund this community-centric amenity.
A 19'-6" x 10’-6” CON/SPAN® B-Series Bridge System, 95' in length, was selected for its ability to provide ample room for traveling pedestrians in a highly attractive arch configuration. This combination made it ideal for creating an inviting passageway below Fleur Drive. Overall, the precast bridge system included 12 arches, 2 headwalls and 4 wingwalls. To further expedite the installation, these components were placed on 4’ wide x 2’ thick (for the arches) and 3' wide x 2' thick (for the wingwalls) precast EXPRESS® Foundations. In keeping with the signature look of the underpass, the precast headwalls and wingwalls were equipped with a stone veneer in the field.
With Fleur Drive being one of the busiest north/south roadways in the Des Moines metro area, the project could not be completed with a full road closure. Thus, it had to be completed in phases to maintain traffic connectivity. The proximity of Gray’s Lake to the project also made things extra challenging in terms of water interference during construction. This was compounded by the fact that in-situ soils were quite weak, forcing the excavation to be deeper than originally anticipated to create a suitable footing platform. The modular nature of the precast components and EXPRESS Foundations helped to minimize those factors and keep the installation schedule on target.
“Contech’s engineering staff was instrumental in the development of this important project," concluded Terry Cole, Lead Design Engineer from Calhoun-Burns & Associates, Inc. "From the original structure concepts and accurate cost estimates, to trouble shooting during design phase, to the final placement of the precast units, they were able to create custom forms at a reasonable cost to meet specific site constraints and the client’s wishes.”
Technical Description:
• 19'-6" x 10’-6” x 95' CON/SPAN
® B-Series Bridge System
• 4’ x 2’ EXPRESS
® Foundations
• 3’ x 2’ EXPRESS® Foundations
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