The “induced travel” effect is a net increase in vehicle miles traveled (VMT) across the roadway network due to an increase in roadway capacity. Adding capacity can increase the average travel speed on the roadway (at least initially), increase travel time reliability, and make driving on the roadway appear safer or feel less stressful. It might also provide access to previously inaccessible areas. All of these effects reduce the perceived “cost” of driving. And when the cost of driving goes down, the quantity of driving goes up. Accounting for induced travel in transportation planning is important from the standpoint of accurately assessing both the benefits and costs of projects that expand roadway capacity. This brief summarizes the robust empirical evidence on the magnitude of the induced travel effect and discusses the limitations of travel demand forecasting models in fully capturing the effect.
Finding ways to boost transportation access for underserved populations can unlock broad social benefits. Micromobility programs, including bikesharing, offer scalable solutions. National, state, and regional housing and urban development agencies promote affordable housing and transit-accessible developments by funding programs such as the Low-Income Housing Tax Credit and Community Development Block Grants. However, these efforts are not always coordinated and the physical distance between affordable housing and transit access continues to grow. The problem is compounded by low car ownership rates in lower income urban communities. These circumstances have led to inequitable mobility access. To correct course, pairing affordable housing developments with reliable transit services is essential. This practice can increase equity and accessibility. A team at the University of California, Davis, conducted a case study in Sacramento, California, to explore bikesharing as an option for connecting affordable housing residents with transit services. This brief summarizes the findings from that research and provides implications for the field.
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While hydrogen fuel-cell electric vehicles (FCEVs) are seen as a part of California’s efforts to decarbonize transportation, especially for the heavy-duty vehicle sector, their role remains unclear. This may change, however, with the launch of the California Alliance for Renewable Clean Energy Hydrogen Energy Systems (ARCHES) developed by the California Governor’s Office of Business and Economic Development (GO-Biz) as a public-private partnership. The U.S. Department of Energy and ARCHES recently signed a $12.6 billion agreement to build a clean, renewable Hydrogen Hub in California, including up to $1.2 billion in federal funding. The transportation sector will play a central role in this effort, including commitments to deploy 6,000 FCEVs, mainly trucks and buses, along with 60 refueling stations and other investments.
Highway speed limits are increasing across the United States. There is also a national trend toward uniform speed limits, within states, for both passenger vehicles and trucks. California is one of only seven remaining states that sets different speed limits, with lower speed limits for trucks than passenger vehicles. While higher speed limits provide operational benefits by shortening travel times and fostering economic benefits—especially for the trucking and logistics industries—they can also increase the likelihood and severity of crashes since higher vehicle speeds require longer stopping distances and generate more energy during a collision.
During the pandemic, California’s four major rail systems— Bay Area Rapid Transit (BART), San Diego Metropolitan Transit System (MTS), Sacramento Regional Transit (SacRT), and Los Angeles County Metropolitan Transportation Authority (LA Metro)—experienced an average ridership decline of 72 percent between 2019 and 2021. BART had the greatest decrease (87 percent) and MTS the lowest (47 percent). However, ridership changes varied significantly across individual stations, with stations located in the central business district or at the end of lines having the highest ridership losses. Land use, development density, and the pedestrian environment are strongly associated with station-level transit ridership. We examined how these characteristics affect transit ridership pre- and post-COVID and how they differ across station types based on longitudinal data collected between 2019 and 2021 for 242 rail stations belonging to BART, MTS, SacRT, and LA Metro.
The concept of Universal Basic Mobility (UBM) calls upon policymakers to ensure all people have access to transportation services for basic needs like work, food, and healthcare. Pilot programs in California and beyond are testing UBM as a means to address the problem of transport poverty, often defined as a household spending more than 10% of their income on transportation (the average American household spends 16%). Transport poverty also encompasses issues of mobility access (e.g., how far a person can travel and what types of destinations they can reach in a defined amount of time) and transportation experience (e.g., safety). Those particularly vulnerable to transport poverty include low-income households, communities of color, undocumented immigrants, persons with disabilities, and youth who are neither working nor in school.
More systematic coordination between transportation and housing development is increasingly recognized as a promising strategy for creating more sustainable communities. In California, the importance of transportation-housing coordination is reflected in recent legislative efforts to address the state’s long-standing housing affordability crisis. One approach is to encourage higher density affordable housing developments near transit or in similarly transportation-efficient areas, such as locations with low vehicle miles traveled (VMT). However, little is known about how transportation access should be considered in guiding housing development, what challenges can arise from coordinating housing development with transportation, and what the state can do to better deal with these challenges and achieve more equitable residential densification.
The amount of traffic on California’s roadways decreased by approximately fifty percent during the COVID-19 pandemic lockdown in March and April of 2020. Conventional wisdom led to the expectation that reduced traffic would result in reduced ozone (O3) concentrations—ozone being a main component of smog—yet ozone concentrations increased during this period. Internal combustion vehicles emit oxides of nitrogen (NOx) and volatile organic compounds (VOCs). These emissions are precursors for ozone formation, but the relationship between these precursor emissions and the final ozone concentration is complex. The ratio of NOx/VOCs determines if the ozone formation will be “NOx-limited” or “NOx-rich”. Major NOx reductions are required to reduce ozone concentrations when the atmosphere is NOx-rich. Small NOx reductions in a NOx-rich atmosphere can actually increase ozone concentrations.
The widespread adoption of electric vehicles (EV) is a centerpiece of California’s strategy to reach net-zero carbon emissions, but it is not fully known how and where EVs are being used, and how and where they are being charged. California is home to approximately half of the EVs in the United States, yet policymakers attempting to guide transportation electrification lack rigorous estimates of how much electricity EVs are actually using because the majority of EV charging occurs at home, where it is difficult to distinguish from other household uses recorded on the electricity meter.
Micromobility—including bicycles, electric bicycles, and electric scooters—is well-suited to address first- and last-mile connectivity with public transit by bridging the gaps of service for riders. This extends the geographic region where residents are likely to access and exit a transit station, facilitating access to more jobs, services, and recreation. However, public use of micromobility depends on a variety of factors. These include availability of secure parking facilities or other environmental design features at and around public transit stations. UC Davis researchers and urban design experts considered these issues in a case study of the Bay Area Rapid Transit (BART) heavy rail system. The study included environmental audits at 18 BART stations. The study also hosted an online survey of BART and micromobility users and included interviews with government, industry, and community stakeholders. This policy brief summarizes the findings from this study and provides policy implications.
