Using Isochrone Maps and OD Matrices to Assess the Impact of High-Speed Rail on Multimodal Regional Mobility in California

California is looking to build the United States’ first high-speed rail (HSR) network. The California High Speed Rail (CAHSR) is expected to have significant impacts on regional mobility. While the consensus is that high-speed rail will decrease intercity travel times, it is uncertain to what extent time savings will be realized for the residents of the major urban centers in California. The main goal of this research is to quantify and visualize the impact of the CAHSR on regional travel times across the state. Isochrone maps and origin-destination (OD) travel time matrices were developed using ArcGIS and advanced ArcGIS extensions (Network Analyst and Model Builder) for each of four different existing intercity transportation networks (car, train, bus, and air) and two additional future networks reflecting the two construction stages of the CAHSR (stage I: San Francisco to Los Angeles, and stage II: additional extensions to Sacramento and San Diego). Isochrone maps were produced for 11 major attractions across the state: the cities of San Francisco, San Jose, Los Angeles, San Diego, Redding, Sacramento, Fresno, and Bakersfield; and the Yosemite, Sequoia, and Joshua Tree national parks. Travel times (weighted by population) were computed between these 11 attractions and 460 cities across the state. The results of this study indicate that significant time savings (an average travel time reduction of 31%, in comparison to the car) will be achieved through the development, construction, and operation of the CAHSR system, and the impact on intercity travel times can be readily demonstrated and understood using GIS tools and isochrone maps.