California's transportation infrastructure is vulnerable to the impacts of climate change and agencies across the region, including Caltrans, are actively studying the infrastructure that is at risk and identifying potential mitigation strategies to various potential climate change impacts. In Monterey County, two agencies recently completed studies related to analyzing climate change impacts to transportation infrastructure: the City of Monterey and the Association of Monterey Bay Area Governments. During the Committee meeting, both agencies will speak to their studies assessment and findings, particularly any potential impacts to bicycle and pedestrian infrastructure.
The Bicycle and Pedestrian Facilities Advisory Committee received an update and provided input to AMBAG's study during their June 3, 2020 meeting. Both studies are linked as web attachments and below are are brief summaries of their reports:
City of Monterey: Transportation Adaptation Plan
The City of Monterey is at a crossroads for deciding on the impact of sea level rise on its transportation system. Sea level rise threaten to permanently flood Del Monte Avenue, a critical regional corridor. The City must consider whether to protect existing infrastructure by walling off the downtown from the Monterey Bay or embrace a new waterfront by giving back Lake El Estero to the sea and adapting the surrounding transportation infrastructure. This study is the first step in making that decision. This study examines the risks that sea level rise poses to transportation facilities, the people of Monterey and other critical infrastructure.
Based on the public survey results and stakeholder input, the City of Monterey has selected these options for the City of Monterey Transportation Adaptation Plan:
- OPTION 1A: Retreat via Del Monte Avenue viaduct: A pedestrian, bicycle, transit, and vehicle viaduct would maintain access to Cannery Row side of Monterey with the event of sea level rise.
- OPTION 1B(i): Retreat via Pearl Street viaduct: abandon Del Monte Avenue and redirect pedestrian, bicycle, transit, and vehicle traffic to Pearl Street, which is widened and elevated.
- OPTION 1B(ii): Del Monte realignment to Pearl Street: similar to 1B (i), renaming Pearl St. Del Monte and including an alternative route through the neighborhood near the Naval Postgraduate School.
- OPTION 1C: Fremont Street improvements: all traffic is redirected to Fremont Street, which is elevated and improved with a bus-only lane and a parking structure to encourage visitors to park and ride on the transit corridor.
- OPTION 2: Flood barriers/sea wall: An elevated coastal trail on a 13-foot high sea wall across the street from Lake El Estero or an approximately 17-foot high vertical concrete seawall keeping the path at grade (losing the ocean views). A sea wall could be erected on the coast side of the existing Coastal Trail at the Municipal Beach between Fisherman’s Wharf and Park Avenue. The sea wall would provide near term protection against waves and coastal surge and in the long term would provide a permanent barrier against higher seas.
The City of Monterey has created a public engagement platform called Have Your Say Monterey (see web attachment) where updates, comments, questions and ideas will be posted. Staff has launched an “ideas tool” where members of the public can create virtual post-it notes to share their thoughts and suggestions.
The Plan was adopted during the City of Monterey's February 2nd, 2021 meeting. The associated staff report is included as a web attachment to this report.
Association of Monterey Bay Area Governments: Central Coast Highway 1 Climate Resiliency Study
The Central Coast Highway 1 Climate Resiliency Study examined the Highway 1 corridor near Elkhorn Slough. The study presents significant challenges to the future of transportation in the Monterey Bay region under conditions of climate change and sea level rise. Elkhorn Slough is California's third largest tract of tidal wetlands and hosts extraordinary biological diversity, providing critical habitat for more than 135 aquatic birds, 550 marine invertebrate species, and 102 fish species. Changes to the road and railway infrastructure will likely affect these important ecological resources. This multi-benefit planning study identifies the needs and opportunities to improve transportation mobility, safety and efficiency, promote healthy coastal habitats, and provide economic security and benefits to the local community.
The study presents a detailed understanding of risks and options for adaptation in this critical stretch of Highway 1 and the railway corridor, as well as an adaptation management strategy to ensure updated scientific information is integrated into the project planning process. 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.
The roadway and railway adaptation scenarios were evaluated using best available modeling tools to investigate systemic changes to transportation, hydrology and ecology triggered by certain adaptation actions. The results of the transportation modeling indicate that the four-lane elevated Highway 1 would best suit the needs of the corridor, allowing for increased capacity on a road that is already overburdened by demand. The benefit-cost analysis finds that a four-lane elevated Highway 1 would be economically justified, since the value of reduction in traffic delays would be greater than the costs associated with transportation and ecological improvements.
Both build scenarios of elevating a 2-lane highway, and elevating and widening the highway to 4 lanes incorporate the Monterey Bay Sanctuary Scenic trail. The Sanctuary Scenic Trail will pass through Moss Landing and operate as a Class 1 Bikeway to provide bicycle and pedestrian travel on a separate right-of-way. The bikeway is planned to be 12 feet wide and would start at the intersection of Moss Landing and Highway 1. It runs parallel and west of Highway 1 heading north, and crossing the existing highway bridge. This study does not propose any further bicycle/pedestrian infrastructure.
An engaging video portraying the sea level rise impacts analyzed in the AMBAG study is included as a web attachment.