Resilient Coastal Roads

A  unique 20 year partnership  between the California Coastal Commission and California Department of Transportation (Caltrans) has provided an important foundation for the state to more holistically approach the threats that climate change, especially SLR, present to critical infrastructure along the 1,200 mile California coast. Specifically, the partnership is improving the department's response to SLR with alternative approaches such as: applying a corridor perspective, avoiding loss of coastal resources, pursuing phasing strategies, and incorporating nature-based measures.

Focusing on integrating coastal resource policies into transportation project planning, design, and environmental review, the Coastal Commission and Caltrans continue to expand their work with other stakeholders to address the threats and uncertainties that climate change poses to shoreline communities, industries and economically- and environmentally- valuable coastal resources.

Try This: Scroll down the page to explore the four key insights of resilient transportation resulting from this partnership or choose a link to an insight of interest from the banner above.

The challenge of sea-level rise cannot be solved on a project-by-project basis. The standard approach of focusing improvements on one isolated asset at a time, such as a bridge or culvert, does not ensure a fully functional corridor. The corridor approach to planning includes examining all interconnected assets and making planning and investment decisions that will ensure travelers reach their destinations now and in the future.

The map below highlights case studies where Caltrans and the Coastal Commission are working together to apply a corridor planning perspective.

A phased adaptation approach includes pursuing short- and medium-term, incremental measures to maintain transportation services in the face of coastal hazards in ways that do not prejudice future opportunities and that also buy additional time to design longer-term and more resilient adaptation strategies.  

Nature-based adaptation strategies increasingly appear to hold promise as a more resilient approach to sea level rise adaptation. Incorporating ecological principles into nature-based shore protection strategies supports multiple benefits, including hazard adaptation and mitigation, natural resource enhancement, as well as recreation and scenic resource preservation. We also highlight that one of the most effective nature based strategies is referred to as “avoiding coastal squeeze.” When rigid infrastructure or hard armoring, such as seawalls or revetments are used on the coast our beaches, wetlands and public recreation areas, can be lost to inundation as they are squeezed between the hard shoreline and rising seas. When we realign our coastal infrastructure to allow for the coastal features like marshes or beaches to naturally migrate inland, we avoid coastal squeeze and keep the best parts of our coast and the ability to access them. Depending on the geologic setting and adjacent urban or rural development, critical infrastructure can be adapted in different ways to avoid the loss of valuable coastal areas by using strategies such as realigning, elevating, or tunneling structures, however this is more difficult in urban areas.

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