Technical Description:
• CON/SPAN
® O-Series
® Bridge System
• Span: 26'
• Rise: 8'-6 3/8"
• Length: 28'-2"
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After the original stream crossing structure at Garrett's Mill Road over Israel Creek was washed out during an extreme flash flood event, an emergency replacement was needed.
"Extensive damage to the stone masonry abutments during the South County flood event compromised the structure and required a complete replacement," stated Blair Reynolds, Chief Project Manager of the Division of Engineering for Washington County's Department of Public Works. "The crossing serves as the main route for local residents who saw their commutes increase 3.5 miles throughout the closure.”
After weighing the alternatives, the Design-Build team decided during the pre-bid phase that a 26' x 8'-6 3/8" CON/SPAN® O-Series® Bridge System from Contech Engineered Solutions, 28'-2" in length, would be the best solution to address the key project requirements. These requirements included optimizing hydraulic performance for the allowable structure depth, rapid construction due to the use of precast arches, headwalls, wingwalls and footings, flexibility in the design of the wingwalls and headwalls that allowed for direct mounting of the traffic railing to the top of the walls, and aesthetic treatment options that matched the look of the stone arch bridges in the area.
“Contech’s field installation engineer was very helpful in getting the bridge perfectly set and anchored," said George Stone, President of Building Systems, Inc. "Contech provided a very good solution to a difficult project.”
Additionally, a cost effective 1.5" relief architectural surface treatment was added to the structure, further enhancing its aesthetic appearance. The two precast headwalls and the four 12' long precast wingwalls were designed for a TL-2 structure-mounted guiderail.
Once the dewatering was in place, all precast components including precast footers, arch units, headwalls, and wingwalls were installed via crane in about three days. In conclusion, the project was a success and Garrett's Mill Road was reopened very quickly and efficiently.
"Contech's engineering team was involved from the beginning to assist with member sizing due to crane lifting limits, design of the wingwalls and headwalls for collision forces and detailed construction support," stated Micah Ceary, PhD, PE, DBIA, Director of Bridge & Structural Division & Engineer-of-Record for Brudis & Associates, Inc. "Overall, the Design-Build team was very satisfied with the construction process and final product."
The Garrett's Mill project was nominated for the 2020 Maryland Quality Initiative (MdQI) award for Local Municipalities less than $5,000,000 and received the 2020 Award of Excellence from the American Council of Engineering Companies/Maryland (ACEC/MD). ACEC/MD's annual Engineering Excellence Awards recognize projects that "demonstrate a high degree of innovation, achievement, and value."
"The precast CON/SPAN structure allowed the contractor to quickly and easily set the units in place with on-site representatives providing valuable information and instruction throughout the process,” concluded Reynolds.
Technical Description:
• CON/SPAN
® O-Series
® Bridge System
• Span: 26'
• Rise: 8'-6 3/8"
• Length: 28'-2"
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