Publication Date

Fall 2022


Cal Poly Humboldt Environmental Resources Engineering Senior Capstone.

The California Department of Transportation (Caltrans) is highly concerned sea level rise (SLR), due to climate change and the potential negative impacts on the California transportation system. SLR is especially important for routes constructed at low elevations and those immediately adjacent to the coast where SLR is one of the largest threats to the transportation system along the coast. Rising sea levels are expected to disrupt the daily lives of Californians, specifically the coastal economies, which increases the risk to public safety and contributes to the decline of ecosystems that are vital to the survival of endangered species (State of California 2022).

The team recommends the Bridge Alternative design that consists of three Reinforced Concrete (RC) Box Girder Bridges in the north, middle and south tsunami zones. The south bridge is the largest structure, with four lanes and a length of 3,000 ft. over a portion of the lagoon, compared to the north and middle zone bridges that are both slightly less than 300 ft. long with only two lanes, as shown below in Figure 1-2. Along the coast of northern California, US Highway 101 mostly runs parallel to the coast, as shown in Figure 1-1. North of the town of Trinidad, CA, between post miles (PM) 108.77 to PM 112.54, the highway lies at low elevation and bisects a portion of Big Lagoon. Due to this low elevation, Caltrans has identified the four-mile section as a high-risk area regarding the impacts from SLR. The team was tasked to determine an appropriate design for protecting the stretch of highway along Big Lagoon from the impacts of SLR. Four different alternatives are designed based on the criteria and constraints identified by the client.