SR A1A Repairs

In October of 2016, Hurricane Matthew hit the east coast of Florida, causing extensive damage to several sections of A1A in Flagler County. RS&H was initially selected by FDOT to assess the storm damage and develop a temporary stabilization plan until permanent repairs could be constructed. Following the completion of those temporary repairs, RS&H was retained under a separate contract to serve as lead designer for the permanent repairs of three segments of SR A1A.

The repair/revetment project extended a total length of 2.4 miles, and provided roadway stabilization, curbed swales, French subdrain systems, and beach nourishment solutions to address the extensive damage caused by Hurricane Matthew. The corridor improvements extended from South 28th Street to South 22nd Street, from South 22nd Street to 9th Street, and from North 18th Street to Osprey Drive. This corridor serves as an important evacuation route for emergency vehicles and recovery efforts during natural disasters.

RS&H modeled the coastal storm surge, wave action, and anticipated scour depths using coastal analysis and computer simulation modeling in order to yield the most cost-effective risk reduction to the department. RS&H’s design included reusing excavated sand from the French subdrain system and landscaping along the beach side of SR A1A that require little to no maintenance. To protect the slope areas from future storm surge and scour, the team proposed a buried secant-auger pile protection system as a foundation to a buried reinforced concrete cantilever bulkhead, which minimized impacts yet provided a robust and durable support for the highway in the event that the dunes are compromised.

The team partnered with FDOT and the Florida Department of Environmental Protection to ensure dune restoration efforts and optimal context sensitivity were taken into consideration. Residents were involved directly in the public outreach efforts and their concerns reflected in the low impact natural landscaping and the use of drilled auger piles versus driven piles, which reduced noise and vibration, protecting wildlife in the area. In addition, glass fiber reinforced polymer (GFRB) composite reinforcement was used in place of steel. GFRP composites eliminate concerns of steel corrosion and perform well in harsh marine environments. GFRB have proven highly cost effective in disaster-resistant structures, are easier to handle and install, and provide longer service life.

The beach area and residential uses along the project corridor required continued access to properties adjacent to SR A1A in conjunction with the appropriate traffic control plan, provision for maintenance of pedestrian and bicycle traffic, restoration of signing and pavement markings, and permanent prohibition to parking along the three segments of SR A1A (beach side) in order to properly establish dune vegetation.

While all of this was challenging, the design was extremely cost effective and resulted in a $17,800,000 savings compared to the initial FDOT project budget. The final cost for construction for the corridor improvements was $22,836,500, which reflected the overall efficiency of the design. What is also impressive is that anyone driving the corridor, bicycling along the route, or enjoying the beach only sees a beautiful beach with pristine dunes; all of the structure described is buried and completely out of sight.

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