Central Coast Highway 1 Climate Resiliency Study



SB1 Adaptation Planning Grant: Initial Case Study

Challenge: Developing plans and strategies



Brief Summary

The eight-mile stretch of Highway 1 near Elkhorn Slough is already constrained and will be increasingly impacted by coastal storm flooding and sea level rise. Driven by a need to sustain this critical transportation corridor and protect the iconic coastal habitat in the face of the challenges posed by climate change, a suite of partners in the Monterey Bay area are working together to find innovative ways to address this complex transportation adaptation problem. The project aims to explore creative transportation solutions and the use of natural infrastructure approaches to promote transportation, habitat, and economic resilience for the region.

The Association of Monterey Bay Area Governments (AMBAG), in conjunction with The Nature Conservancy (TNC) and the Center for Blue Economy (CBE), will prepare a climate resiliency study for the Central Coast Highway 1 corridor from State Route 156 near Castroville to Salinas Road near the Monterey/Santa Cruz county line. This study will provide a conceptual climate change adaptation transportation planning foundation for integration into the AMBAG Metropolitan Transportation Plan/Sustainable Communities Strategy (MTP/SCS). This effort will identify transportation improvements and sea level rise adaptation strategies for Highway 1 that can improve transportation mobility, safety and efficiency, promote healthy habitats, and provide economic security and benefits to the local community. The goal of this collaborative approach that the completed plan will lead to implementation and development of adaptation projects, by being incorporated into local and regional plans.

This two year project kicked-off in spring 2018.

Lead Agency and Partnerships

AMBAG is the project lead, in partnership with The Nature Conservancy (TNC) and Center for the Blue Economy (CBE). In addition to the leads of the project, there will be steering committee involvement. More information on the steering committee can be found in the “Engagement Process” section of this report.


This project will help local governments in the AMBAG Region in addressing climate change. The project supports State initiatives and priorities including EO-S-13-08, which directs state agencies to plan for sea level rise and climate impacts. This project will allow the region to prepare for sea level rise and climate change impacts to Highway 1 within the study area, and the results will have translatable findings along the coastal highway. Per Senate Bill 379 (SB 379), local governments must address climate change adaptation and resiliency in their general plans. This project will provide information that can be included in General Plan updates to address coastal resiliency along the Monterey Bay coastline. In furtherance of the intention of the ICARP Program, this analysis will link regional climate vulnerabilities with adaptation guidance from the state level.  This project would not be possible without the funding made available through this Adaptation Planning Grant.

Engagement Process

Through the development of the plan, the project will identify vulnerable populations through the involvement of local stakeholders and the Steering Committee.

The project’s Steering Committee is comprised of representatives from the relevant transportation agencies (Caltrans at both Headquarters and in District 5, AMBAG, and TAMC), as well as the relevant coastal management agencies (the California Coastal Commission, the California State Coastal Conservancy, Monterey County’s Resource Management Agency, and the Elkhorn Slough National Estuarine Research Reserve), local non-profits specializing in coastal resilience and restoration, and an academic institution (CBE).

The project will demonstrate an on-going collaboration and long-term partnership between sectors and jurisdictions, and across levels of government at a regional scale. The project will work closely with diverse external stakeholders and members of the public incorporating their considerations into the process for identifying adaptation approaches and selecting which are the best to consider for this stretch of coastal highway and habitat. Community workshops will be held, as well as other engagement to engage local communities, with their comments being incorporated into the final plan.

Climate Impact Area

Transportation infrastructure is prone to flooding and vulnerable to sea level rise, and is adjacent to valuable wetland habitats of Elkhorn Slough National Estuary. Much of these valued habitats are also vulnerable to sea level rise. We have an opportunity to increase the resilience of transportation infrastructure and habitat to sea level rise and climate change. This effort will create a new model for transportation planning that increases the resilience of transportation infrastructure by proactively addressing climate change impacts while simultaneously addressing existing issues, such as reducing flooding risk, greenhouse gas emission, etc.

Funding Source

Adaption Planning Grant: $360,000

Local Cash Match: $69,919 ($35,000 cash/in-kind from AMBAG, $28,603 cash/in-kind from TNC and $6,316 in-kind from the CBE)

Total: $421,919

Research and Data

Gather existing vulnerabilities and background data and reports by identifying opportunities and constraints as well as standards that should be used to guide preparation of the plan such as climate change projections (precipitation, sea level rise and storm surge, wildfires, and temperature), asset locations and information, existing and planned land uses, population characteristics, regional economic assets and conditions, existing transportation conditions and travel projections within the project area.

In addition to the data above the project will inventory, map, and evaluate vulnerable transportation infrastructure, natural resources, and transit dependent communities. Data will be gathered from Cal-Adapt and the regional travel demand model produced by AMBAG.


Timing and coordination are going to be the biggest challenges for this project.


This project will develop a framework for addressing climate change vulnerabilities along the Highway 1 corridor. This evaluation framework will integrate consideration of the values of natural resources with corridor transportation needs, as well as consider a sustainable transportation corridor that supports a growing population, a vibrant economy, and preserves sensitive coastal habitat.

The project aims to:

1) Overcome the shortcomings of traditional corridor studies by developing an analytical approach that merges consideration of the values of natural resources with transportation mobility and efficiency priorities; and

2) Develop a decision support process to identify the best adaptation pathway (timing and approach) that reflects an understanding of risks over time as well as consequential negative ancillary impacts to the environment and economy.

The economic analysis will consist of two phases: (a) an economic cost benefit and impact analysis, and (b) an assessment of risks to determine the appropriate timing of sequential adaptation actions. The two elements will combine to design the most cost effective adaptation pathway.

Knowing that there are multiple options for adaptation, some of which are cost-superior and some of which are much closer in cost and benefits depending on assumptions, is useful, but still does not facilitate immediate decision-making on critical vulnerabilities. We will develop an evaluation framework to facilitate that decision-making and prioritization process.


A new evaluation framework will be established through this project.  This new framework will pave the way for holistic corridor management in the face of climate change, not only for the Monterey Bay area, but across the California coast in other places where environmental and infrastructure vulnerability coincide.

Additional Resources 


Information on AMBAG’s Regional Travel Demand Model

Further Information

For additional information, please contact Heather Adamson: (831) 264-5086; hadamson@ambag.org