Current navigation applications estimate travel times based on current traffic conditions, without considering upcoming travel demand. A potential solution to this problem is a central coordination system that collects global travel demand information, enabling more accurate traffic projections. Monetary incentives or charges can be used to encourage drivers to follow assigned routes that contribute toward a system optimum, which represents the most efficient traffic state for the transportation network. The challenge in determining incentives lies in the heterogeneity of drivers, as each has different preferences. Traditionally, surveys have been used to estimate drivers’ routing preferences, but these suffer from respondent inconsistency and changing driver preferences. This research proposes a utility learning mechanism. Instead of relying on static survey data, the system periodically updates its understanding of drivers’ preferences by observing their route choices over time. This research brief discusses the results and effectiveness of the coordinated routing system and the utility learning mechanism.
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In California, local option sales taxes (LOSTs) are adopted by voters to increase the retail sales tax. Revenues are used to fund specific transportation projects. Meanwhile, metropolitan planning organizations (MPOs) are required by Senate Bill 375 to develop long-range plans to achieve reductions in vehicle miles traveled and emissions. But MPOs do not directly control the sponsorship or funding of most transportation projects in these plans. LOSTs are not bound by requirements of SB 375, even though MPOs must still account for impacts of LOST spending. In this context, an important question is whether and how LOST measures influence transportation planning priorities. To explore this question, researchers from the University of California, Davis, examined county LOST measures and regional transportation plans in California’s “big four” MPO regions—the San Francisco, Los Angeles, San Diego, and Sacramento metropolitan areas. This policy brief summarizes the findings from that research and provides policy implications.
In this project, researchers from the University of California, Davis reviewed key, rapidly implementable strategies to mitigate emissions from cement and concrete used in state funded infrastructure projects. The research included performing a series of analyses to determine emissions reduction pathways throughout the cement life cycle, highlighting the potential to reduce emissions by designing new infrastructure for increased material efficiency. This policy brief summarizes the findings from that research and provides policy implications.
Second-hand (SH) vehicle imports from the US comprise nearly 20 percent of the 30 million light-duty vehicles (LDV) currently registered in Mexico. As demand for electric vehicles (EVs) in Mexico grows and the share of EVs in the US fleet continues to increase, the SH EV market in Mexico is likely to start developing, introducing new challenges for vehicle lifetime and end-of-life (EoL) management needs. Using system dynamics modeling, researchers at the University of California, Davis, developed scenarios to project future trends in EV adoption and SH vehicle trade flows in Mexico. Results indicate potential synergies with respect to market timing, but also a risk of disproportionate burdens from spent batteries in Mexico, since used EVs have less remaining battery life and thus generate spent batteries more quickly than a new EV. This trade of SH EVs between Mexico and the US should be managed bilaterally, ensuring that imports to the country deliver sufficiently long operational lives, and exploring opportunities to set up regional battery recycling systems to recover critical minerals, so that the burden of EoL managements do not outweigh the benefits of affordable EVs.
Transportation safety is a public health issue ofincreasing importance as rates of traffic fatalities and serious injuries continue to rise. The Safe Systems Pyramid presented in this policy brief is a tool that incorporates public health principles to evaluate transportation safety policies and interventions. The Safe Systems Pyramid can help transportation practitioners and decision-makers prioritize projects for safety and communicate priorities to the public. For decades, the traditional “Es” framework of transportation safety has implied equal weight between engineering, enforcement, and education interventions. Because these interventions are not equally effective, the Es paradigm neglects public health principles, which prioritize population-level interventions that require less individual effort and focus on the pathologic agent—in this case, the transfer of kinetic energy. The Safe Systems Pyramid combines two models for these principles: the Health Impact Pyramid prioritizes interventions that have increasing population health impact and decreasing individual effort; and the Hierarchy of Controls, used in occupational safety, organizes strategies by effectiveness.
Many US cities aim to increase environmentally sustainable modes of transportation, such as cycling or public transit. However, the current built environment in many of these cities does not adequately support cyclists or public transit riders. Bicycle infrastructure can minimize cyclists’ exposure to high-speed automobile traffic and increase the actual and perceived safety of cycling. Bicycle infrastructure can also potentially improve connections to public transit stops and stations. However, planners lack the tools to effectively measure where bicycle infrastructure improvements will yield the best outcomes. New research from Georgia Tech addresses this problem by developing two new modeling tools, BikewaySim and TransitSim, to assess how bicycle infrastructure can affect cycling and public transit access. Using BikewaySim, the researchers modeled over 28,000 potential cycling trips, calculating the impacts of two proposed cycling infrastructure projects in Atlanta, Georgia. Using TransitSim, the researchers modeled combined cycling and transit trips from four distinct locations in Atlanta, Georgia. This brief summarizes the findings from that research.
E-commerce has become a fundamental part of the shopping experience. It has transformed how consumers shop and, in many cases, it has improved accessibility to goods and services. Another benefit is the substitution of personal shopping trips with consolidated deliveries, which can significantly reduce transportation-related negative externalities from urban goods movements. However, the recent trend towards consumer-focused services in last-mile distribution has adversely impacted the economic viability of urban goods movement. Frequent less-than-truckload last-mile deliveries can lead to increased freight distribution costs and associated environmental externalities. Opportunities and challenges associated with alternate last-mile distribution strategies were studied by researchers at the University of California, Davis. The study examined ways that companies might adapt to increasingly consumer-focused trends in e-commerce towards rush delivery within strict time windows (expedited logistics). The team developed an explicit dynamic and stochastic location-routing model to assess the performance of several distribution initiatives. This policy brief summarizes the findings from that research and provides policy implications.
Open-loop fare payment systems are an emerging technology that allows customers to pay with credit cards, debit cards, smartphone applications, and digital wallets when boarding transit vehicles or entering platform areas. The California Integrated Travel Program (Cal-ITP) aims to foster the implementation of open-loop payments among California’s transit agencies. What do transit agencies have to say about this goal and the challenges it might pose for them and their travelers? Researchers from the University of California, Davis gathered surveys from a small sample of transit agencies (N = 21) and found that agencies are interested in open-loop payments, agencies and passengers would likely support it, but that it also presents challenges for agencies and passengers. This policy brief summarizes the findings from that research and provides policy implications.
Micromobility options such as electric bike-share and scooter-share services are a fundamental part of the existing shared mobility landscape. Research has shown that micromobility use can reduce car dependence. This is accomplished through trip-level mode replacement and adjustments in mode-use configurations in daily travel. Understanding the full potential of micromobility services as a car replacement can help cities better plan for the services to meet environmental sustainability goals. Researchers at the University of California, Davis collected GPS-based travel diary data from individual micromobility users from 48 cities in the US and examined their travel behavior and micromobility use patterns. They found that micromobility services can displace car use. To achieve environmental sustainability goals, cities must pursue options that will deliver benefits, such as micromobility services. This policy brief summarizes the findings from that research and provides policy implications.
Reducing greenhouse gas (GHG) emissions from transportation poses a significant challenge in rural communities and at the edges of metropolitan areas where rural and urban populations meet, otherwise known as exurban fringe. Populations living in these areas rely more heavily on personal vehicle travel than nonrural populations do and are more likely to have trouble getting to and from important destinations. One approach to curtailing transportation GHG emissions is through land use planning, for example by directing population growth into compact, walkable communities with access to transit. However, nearly all research to date on this topic has focused on urban and suburban areas, leaving decision-makers in exurban and rural communities with little guidance for how to effectively reduce GHGs through changes to land use and development in their communities.
Researchers at the University of Vermont sought to answer the question: is the relationship between travel and the built environment the same in urban and rural areas? They analyzed nationwide data from the United States Federal Highway Administration on nearly 110,000 people and detailed information on land use and development from the United States Environmental Protection Agency Smart Location Database. They determined what aspects of the built environment in different types of locations (urban, rural, etc.) were associated with sustainable travel behaviors such as greater rates of walking and biking, less reliance on automobile travel, and fewer vehicle miles traveled or VMT, which is the number of miles driven in a car. This policy brief summarizes the findings from that research and provides policy implications.
