California has experienced a range of significant impacts to its transportation system in the past few years. In 2015, heavy rains washed out a bridge on I-10, impacting travel and goods movement nationwide. In June, 2017 a major landslide along Highway 1 deposited tons of rock to the depth of 65 feet on the roadway. And, most recently, wildfires in both northern and southern California had a significant impact on travelers. Near Santa Barbara, the loss of protective landcover from wildfires resulted in a major mudslide during heavy rains that closed Highway 101 for weeks. In the last year alone, the department incurred over $1.2 billion dollars in highway damage. The state also has over 840 miles of coastline that raise concerns about long-term coastal flooding and the impacts of climate change.
Extreme events like those experienced by California in recent years and the associated costs are expected to become more pronounced and more frequent in the future. Caltrans has undertaken a study to assess the potential impacts of such climatic changes, and to better define future conditions as a first step toward addressing their effects. As noted by Malcolm Dougherty, Caltrans Director, “Climate change poses an immediate and growing threat to California, and Caltrans is being proactive in determining what this means for the state's transportation system. This study and those that will follow intend to provide data to support the discussion about how climate change impacts the way we plan, design, build, operate and maintain the state highway system."
WSP USA has been working in partnership with Caltrans staff to analyze climate data from multiple sources, determine impact metrics specific to transportation program delivery, and develop the first in a series of reports that will ultimately represent an initial inventory of climate change-related effects statewide. The first reports for Caltrans District 4 (Bay Area) – the Caltrans Climate Change Vulnerability Assessment Summary and Technical Reports (http://www.dot.ca.gov/transplanning/ocp/vulnerability-assessment.html) have started a dialogue in the state on how to consider the effects of climate on the transportation system. Julia Biggar, the Caltrans project manager for the study, observed that “information contained within these reports will be important as the state incorporates the findings of this study into Caltrans plans and operating procedures.”
Michael Flood, WSP’s project manager on this effort stated, “Caltrans, the first DOT nationally to address comprehensively the potential effects of climate change, is working to implement a risk-based framework for decisions, recognizing the true value of the transportation system to communities and the potential consequences to society of negative impacts. Caltrans is a leader in this critically important challenge facing both the state and the state’s transportation system.”