Green Infrastructure Techniques for Resilience of the Oregon Coast Highway
The Oregon Department of Transportation (ODOT) green infrastructure solutions for resilience documented in this report are the result of a Federal Highway Administration (FHWA) sponsored pilot project. ODOT analyzed how green infrastructure can help protect the Oregon Coast Highway (US 101) from the impacts of extreme storms and coastal bluff erosion. Through this study ODOT explored the use of nature-based design solutions to protect coastal transportation infrastructure from these climate enhanced impacts.
The highway runs the length of the Oregon coast for 363 miles, and limited space between the roadway and the shoreline makes it highly vulnerable to coastal hazards, related to sea level rise and storms anticipated to worsen with climate change. This study focused on three sites susceptible to erosion and storm surge in Lincoln County, Oregon within a 20 mile stretch of highway 101 that ODOT has identified as highly vulnerable.
Sea level rise and flooding projections were used to inform the conceptual elevation design plans for the three high-risk sites - using a high-range 2050 sea level rise scenario under a 100-year storm event. Green infrastructure solutions such as cobble beaches, artificial dunes, sand tubes, planted terraces and more were analyzed for each site along with estimated construction and maintenance costs, and implementation benefits and challenges. Adaptation Options and Costs are detailed for Beverly Beach, Lost Creek, and Ona Beach:
Beverly Beach has areas of active coastal bluff erosion that threaten the highway. A hybrid design solution includes a “cobble beach covering large rock and riprap keyed in at the toe of the slope with piles…along with a Mechanically Stabilized Earth (MSE) slope with planted terraces.” The total cost estimate is $41 million.
Lost Creek is a low-lying area of highway above the creek that is vulnerable to flooding, storm surge, and sea level rise. Design options are non-structural, and include a cobble beach fronting an artificial dune. The total cost estimate is $2.8 million.
Ona Beach is a low section of highway also vulnerable to river flooding, sea level rise, and storm surge. A hybrid design is being analyzed that includes a cobble beach, MSE Slopes, and a core of sand tubes for structural stability. The total cost estimate is almost $5.9 million.
Publication Date: October 2017
- Oregon Department of Transportation (ODOT)
- Federal Highway Administration (FHWA)
- Best practice
- Case study