Barrier Island Roadway Overwashing from Sea Level Rise and Storm Surge: US 98 on Okaloosa Island, Florida

This is one of nine engineering case studies conducted under the Transportation Engineering Approaches to Climate Resiliency (TEACR) Project. This case study focused on the vulnerability of a barrier island roadway to overwashing from sea level rise and storm surge. In this assessment, the research team investigated an engineering adaptation to increase the resilience of a coastal highway to storm events in rising sea levels. Specifically, this assessment evaluated a Florida Department of Transportation (FDOT) critical coastal roadway with a buried sheet pile wall and gabions along the shoulder. The sheet pile wall and gabions were installed as a countermeasure to reduce roadway erosion from overwashing during storm events. Damage to roads that parallel the coastline is typically caused by overwash of flowing water and wave velocities that scour out the road shoulders and damage the pavement. This damage mechanism is referred to as the “weir-flow-damage mechanism” because the roadway essentially functions like a broadcrested weir during the extreme event. The approach in this assessment is different from the other TEACR engineering assessments in that the recommended adaptation has already been built as a countermeasure in response to repeated damage caused by extreme events. The purpose of this assessment is to learn the effectiveness of buried sheet pile walls and gabions in coastal locations where roadway erosion from overwashing is common and projected to increase in frequency due to sea level rise. The research team also conducted an economic assessment which demonstrated that the buried sheet pile wall and gabion mattress countermeasures makes economic sense for managing current weir-flow risks and the economic argument for adaptation becomes much stronger as sea levels rise.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References;
  • Pagination: 32p
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01663167
  • Record Type: Publication
  • Report/Paper Numbers: FHWA-HEP-17-015
  • Files: TRIS, ATRI, USDOT
  • Created Date: Feb 9 2018 7:56AM