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Posted by Brendon Embry on Jun 14, 2017


The states of Maine and New Hampshire started a project called the “Three Bridge Agreement” in 2011. The project addresses the three bridges that the two states jointly own, including the Sarah Mildred Long Bridge. As part of the agreement, the old bridge would be replaced by a new version that would allow more clearance for ship traffic along with features that bring it to federal interstate highway standards.

After the old bridge was demolished in October 2016, construction of the new bridge began right away. Plans for the new bridge include a higher vertical clearance for ships to pass through on the Piscataqua River; fewer piers for a better gateway span; and concrete towers that will support the lift span. The goal is for the bridge to open in October 2017, and for the bridge to outlast its predecessor.

The concrete towers that support the lift span are impressive. The lift span is a steel box section that will carry vehicle and railroad traffic. This complex design/build project is being managed and constructed by Cianbro Corporation. (Visit their project website for onsite webcams and more.) 

On the approaches, the vehicle bridge is above the railroad bridge. In the lift span, both vehicle lanes and railroad tracks are on the same level above the steel superstructure. Therefore, when trains need to use the bridge, the span is lowered to connect the rail tracks. 

Composite Advantage's role in the project is to supply wind fairings for both sides of the lift span. These will stabilize the bridge during severe weather conditions. The L-shaped fairings are attached to the top and bottom of the lift span superstructure. Since light weight is so important on lift bridges, Fiber Reinforced Polymer (FRP) materials are the perfect choice. The material can be molded to provide the optimum shape. The inherent corrosion resistance of FRP contributes to a very long design life. The wind fairings improve the aerodynamic performance of the bridge span and eliminate any potential undesirable dynamic responses. Inside each fairing, a pedestrian walkway facilitates bridge inspection. Composite Advantage is proud to build these FRP wind fairings for the new Sarah Long Bridge, contributing to a project that will benefit millions of travelers in the years to come.

FRP vs Concrete



Topics: vehicle bridges, wind fairings

AboutBrendon Embry

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