Challenge. Design structures to protect portions of the trail from erosion caused by locally-generated waves

Solution. In support of the Florida Department of Transportation’s construction of a 12-foot wide, 3.9-mile long shared-use trail along SR 60 (Courtney Campbell Causeway) in Old Tampa Bay, INTERA developed coastal design criteria and designed the shoreline protection for the segments of the trail along the causeway. The trail provides alternative modes of transportation (e.g., bicyclists and pedestrians) across Old Tampa Bay while not adversely affecting the vehicular traffic and recreational users of the causeway. To accomplish our design tasks, INTERA applied the results from a loosely coupled circulation (ADCIRC) and wave (SWAN) model that served to simulate historical storms as well as storms shifted north and south of their actual landfall locations. Direct statistical analysis of the simulation results developed the design values of water levels, currents, and waves. We analyzed the scour expected at the proposed trail bridge piers during design flows and examined hydraulics-related design criteria. We also designed the abutment protection for the proposed trail bridge. Two field investigations (one after a large tropical storm) assessed the existing shoreline conditions (including shoreline protection) along the length of the trail. Incorporating the results of the field investigations along with hydraulic design criteria, INTERA proposed two different sections to protect the proposed trail—one section consisting of a rubble riprap revetment and the other section consisting of a seawall or a gravity wall fronted by riprap toe protection.