Sarah Mildred Long Bridge

Description

The Sarah Mildred Long Bridge was built in 1940 to replace a crossing that dated back to 1822. In 2016, the bridge was demolished as part of a project called the Three Bridge Agreement. Due to the multi-functional aspects of this movable bridge and its 100-year design life, the bridge has the distinction of being the most expensive infrastructure project in state history.

The bridge features vertical clearance for larger ships and a steel box lift span capable of carrying vehicle and railroad traffic above the steel superstructure. It is the first bridge of its kind in the U.S. to shoulder four precast 200 ft. tall concrete towers that support a 300 ft. long structural steel box girder lift span.

When engineers needed to stabilize the structure during severe weather and high winds, they turned to FRP. Cianbro Corp., the project’s contractor, selected Composite Advantage to fabricate two sets of FRP wind fairings. Each was engineered to house an internal walkway to accommodate inspection and maintenance activities. The L-shaped FRP wind fairings, the first such product for Composite Advantage and only the second time FRP has been used for this type of application, attach to the top and bottom of the lift span structure.

Construction crews used a crane to lift the wind fairings into place on each side of the lift span, which was assembled on a barge near the towers. The panels were easily adjusted to ensure proper matchup with bolt holes. Once positioned, the fairings were bolted to FRP angles that were then bolted to larger steel I-beams that formed the lift span’s exterior.