Our Insights
Jul 28, 2020
Grist Mill Bridge – Hampden, Maine (2020)

Replacement of an aging steel bridge with a 75-foot single-span structure
Key Stakeholders
- Owner: Maine Department of Transportation (Maine DOT)
- Engineer: AIT Bridges in collaboration with T.Y. Lin International
- Contractor: T-Buck Construction
Composite Solution
Utilization of five Fiber-Reinforced Polymer (FRP) GBeams, each 4'2" deep, supporting a 40'4" wide deck.

Performance Highlights
- Achieved a load test inventory rating factor of 1.66, surpassing the design target of 1.04.
- Demonstrated excellent deflection and fatigue resistance, meeting AASHTO standards.
- Instrumented by the University of Maine and UMass Lowell for performance validation.
Benefits of Composite Materials
- Corrosion-resistant and non-conductive, ideal for Maine's harsh climate.
- Lightweight components facilitated accelerated construction and reduced transportation costs.
- Projected 100+ year lifespan with minimal maintenance requirements.
BI Design & Engineering’s Contribution
- Provided comprehensive design, engineering, and manufacturing services.
- Leveraged proprietary GBeam technology for enhanced structural performance.
- Collaborated closely with stakeholders to ensure project success.
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