Recent itsdavis_ncst_policy items

Benchmarking Global Road Transportation Greenhouse Gas Emissions from 2021–2050

Fri, 27 Feb 2026 00:00:00 +0000

Greenhouse gas (GHG) emissions from transportation are rising globally, particularly in emerging economies, where growing wealth increases vehicle ownership, vehicle use, and expansion of road networks. Road infrastructure is vital to economic development, but its construction, maintenance, and rehabilitation contribute significantly to GHG emissions. While extensive research and policy efforts have focused on emissions from vehicle operation, emissions from road infrastructure have not been systematically benchmarked to support mitigation strategies. A holistic lifecycle approach that integrates emissions from road construction, maintenance, vehicle production, operation, and road surface roughness provides a more complete understanding of climate impact from road transportation. To address these knowledge gaps, researchers at the University of California, Davis developed a framework to estimate lifecycle GHG emissions from road networks around the globe. This framework estimates...

County Sales Tax Measures for Transportation Can Affect Regional Plans for Sustainable Transportation

Mon, 14 Apr 2025 00:00:00 +0000

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...

BikewaySim Expected to Improve Bicycle Infrastructure Planning Process

Thu, 27 Mar 2025 00:00:00 +0000

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....

The Safe Systems Pyramid

Wed, 12 Mar 2025 00:00:00 +0000

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...

Mitigating CO₂Emissions from California’s Concrete Infrastructure

Wed, 12 Mar 2025 00:00:00 +0000

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.

View the NCST Project Webpage

High Percentages of Reclaimed Asphalt Affect the Performance of Asphalt Binder

Wed, 12 Mar 2025 00:00:00 +0000

More than 90 percent of the road and highway network in the United States is paved with asphalt concrete. Maintenance and periodic rehabilitation require a continuous supply of aggregates and asphalt binder, both of which are becoming increasingly scarce and expensive. Recycling and reusing these resources can reduce costs and improve sustainability. The most common recyclable material used in road construction is reclaimed asphalt pavement (RAP), which is milled asphalt surface layers that have been removed from existing pavements before new asphalt overlay is placed. Reclaimed asphalt roofing shingles (RAS) are another potential source of asphalt binder.

There is growing interest in allowing significantly higher percentages of RAP and RAS in asphalt mixes used on state and local roadways. However, making this change has raised concerns regarding how these composite binders may influence the performance and durability of asphalt mixes, depending on the blends of different...

Last-Mile Delivery Innovations and Best Practices in the Age of E-commerce

Tue, 11 Mar 2025 00:00:00 +0000

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...

Challenges Are Present, But California Transit Agencies Are Open to Open-loop

Tue, 11 Feb 2025 00:00:00 +0000

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.

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Trip-Level Mode Replacements and Daily Activity Patterns Reveal the Sustainability Potential of Micromobility

Tue, 4 Feb 2025 00:00:00 +0000

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...

Travel and the Built Environment in Rural Communities

Mon, 6 Jan 2025 00:00:00 +0000

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...

Who Experiences Rural Travel Burdens? Evidence from Car-Limited and Latin American Migrant Households

Mon, 6 Jan 2025 00:00:00 +0000

Transportation systems provide vital connections to essential destinations including jobs, healthcare services, education, and recreational opportunities. However, people living in rural communities face unique transportation challenges, including greater distances to destinations and few high quality transportation options. Barriers to mobility can lead to transportation burdens, such as high transportation costs or unmet transportation needs—whereby trips cannot be made. These transportation burdens can adversely affect well-being. Differences between rural and nonrural areas in the built environment and population characteristics are well documented and studied. However, little is known about the differences in who experiences transportation burdens in rural versus nonrural areas, the factors that drive these differences, and how to improve mobility and access in rural populations.

Researchers from the University of Vermont analyzed national survey data on transportation burdens....

Bikesharing and other micromobility services can improve connectivity between affordable housing communities and transit

Thu, 24 Oct 2024 00:00:00 +0000

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...

Sustainable Incentives for Accelerating the Zero Emission Vehicle Transition

Thu, 22 Aug 2024 00:00:00 +0000

Effective policy tools are urgently needed to enable the United States to keep pace with international climate goals. “Feebates”—fees applied to the purchase of vehicles with higher emissions and rebates for clean ones—have become an effective and increasingly common strategy for shaping vehicle markets in European countries. A holistic policy framework that will accelerate the transition to zero emission vehicles (ZEVs) in the US will likely include strong federal policies such as sales mandates, purchase fees for higher emission vehicles, and purchase incentives for ZEVs. Researchers from the University of California, Davis examined what makes a feebate policy work and how this strategy can be leveraged to shift US vehicle markets. The research included a review and analysis of feebate mechanisms in European countries. This policy brief summarizes research findings and provides policy implications.

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Extending public transit through micromobility facilities and services in the Bay Area

Fri, 9 Aug 2024 00:00:00 +0000

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...

Jobs and Automation in the Freight and Warehousing Sector

Fri, 12 Jul 2024 00:00:00 +0000

Today there are companies experimenting with autonomous mobile vehicle and equipment technologies. These technologies come in various forms, from small delivery robots to large automated heavy-duty trucks and cargo movers. Some of these have been part of the labor force in factories, warehouses, and distribution centers worldwide for some industries, and their expansion is likely. A recent white paper from UC Davis assesses the landscape for freight automation and its potential labor impacts in the freight and warehousing sector; this policy brief summarizes the key findings and policy implications of that research. While there are still more questions than answers, it is known that as the technology matures, the future for workers will depend on policymaker and industry actions. While these actions can have potentially negative effects for some workers (e.g., job loss or reduced job quality), they can have positive effects for others (e.g., improved safety, security, job quality,...

Using Vehicle Miles Traveled Instead of Level of Service as a Metric of Environmental Impact for Land Development Projects: Progress in California

Fri, 12 Apr 2024 00:00:00 +0000

Senate Bill (SB) 743 (2013) and its related regulations eliminated automobile level of service (LOS) and replaced it with vehicle miles traveled (VMT) as the primary transportation impact metric for land development projects under the California Environmental Quality Act. Actual implementation of the LOS-to-VMT shift was left up to lead agencies, primarily local governments. The LOS-to-VMT shift was expected to create many challenges, given the often-limited resources of local governments, the entrenched use of LOS, and the perceived lack of established practice regarding VMT estimation, mitigation, and monitoring. With those concerns in mind, researchers at the University of California, Davis investigated how local governments have been implementing the LOS-to-VMT shift for land development projects. This policy brief summarizes the findings from that investigation.
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Mileage Fees: An Equitable and Financially Viable Alternative to the Gas Tax

Tue, 19 Mar 2024 00:00:00 +0000

In the United States, mileage fees, or road user charges, are being explored as an alternative to motor fuel taxes, often called “gas taxes.” The search for alternatives is motivated by rising fuel efficiency standards and the increasing number of electric vehicles on the road. These factors have diminished the revenue-generating capacity of gas taxes. While mileage fees are a more stable and fuel-agnostic transportation funding source, they face criticism and low levels of public support due to concerns about costs, protection of drivers’ location and privacy, and perceptions that they would raise taxes on low-income and rural households.
Researchers from the University of Vermont Transportation Research Center used data from over 360,000 Vermont vehicles to assess the financial and equity impacts of replacing the Vermont state gas tax with a revenue-neutral mileage fee of 1.5 cents per mile. The researchers then surveyed 623 car drivers in northern New England and 2,114...

Impacts of the Federal Tax Credit on the Decision to Lease or Purchase a Plug-in Electric Vehicle

Mon, 26 Feb 2024 00:00:00 +0000

To mitigate climate change and air pollution, multiple US states and other countries have beensetting and adjusting goals and policies aimed at shifting sales from conventional, fossil-fuel–powered vehicles to plug-in electric vehicles (PEVs), defined as plug-in hybrid and battery electric (all-electric) vehicles. For example, US policies have offered federal tax credits for the purchase of PEVs, with limits set on how many PEVs from a single manufacturer, which PEVs, and which consumers qualify. A key to developing or adjusting these policies is understanding how financial incentives affect consumers’ decisions to purchase or lease PEVs. To better understand the impact of financial incentives on PEV leasing and purchasing, researchers at the University of California, Davis, analyzed survey responses from approximately 2,800 California PEV owners. The survey asked: If the federal tax credit were not available would you: purchase or lease the same PEV, switch to a different...

Benefits of Battery Electric Heavy-Duty Trucks Increase Rapidly over Time

Mon, 26 Feb 2024 00:00:00 +0000

In the United States, the transportation sector is the largest single source of greenhouse gas (GHG) and nitrogen oxide (NOx) emissions, and heavy-duty trucks contribute a disproportionately large share. Therefore, the trucking industry has been seeking ways to minimize emissions, such as adopting zero-emission vehicles and improving truck operating strategies to reduce truck miles. Battery-powered vehicles have different limitations than those with internal combustion engines. In this study, researchers from the University of Southern California investigated the adoption of battery electric heavy-duty trucks (BEHDTs) in the short-haul freight movement sector and the drayage industry. Drayage is a short-haul pickup and delivery service for transporting freight among ports, warehouses, and other facilities. With drayage routing, vehicles have limited weight and volume capacities and often make many stops. Routing involves optimizing for multiple factors, like fuel,...

Household Vehicle Choice in California: Behavior and Impacts

Fri, 16 Feb 2024 00:00:00 +0000

To reduce greenhouse gas (GHG) emissions from the transportation sector, government programs and regulations are encouraging a transition from internal combustion engine vehicles (ICEVs) to battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs), collectively referred to as plug-in electric vehicles (PEVs). California has targets of having 5 million PEVs and Fuel Cell Electric Vehicles on the road by 2030, and 100% of new vehicle sales being zero-emission by 2035. An increasing diversity of vehicle types, paired with a growing demand for PEVs, has major implications for vehicle miles traveled (VMT), air pollution, and emissions. To better understand what is likely to happen, researchers predict household vehicle preference and VMT by vehicle body and fuel type. This policy brief summarizes the findings from that research and provides policy implications.
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California Cities Face Trade-offs in Developing Plans and Policies for Transit-Oriented Development

Mon, 12 Feb 2024 00:00:00 +0000

California has ambitious climate policy goals, while also facing an acute housing affordability crisis. Transit-oriented development—higher-density residential or mixed-use development centered around high-quality transit stations—has emerged as a strategy to reduce greenhouse gases while increasing housing supply. However, transit-oriented development is more complex and expensive to build than development in low-density, undeveloped areas. State and local governments have adopted numerous policies to encourage transit-oriented development, but little research has examined how various policies can be combined to produce on-the-ground success. Researchers at the University of California, Davis completed in-depth case studies of 11 California cities to understand their mix of strategies and how they have needed to reconcile sometimes competing policy goals in advancing transit-oriented development. This policy brief summarizes the findings from that research and provides policy...

Best Practices for Science Communication: Messaging and Reputation

Wed, 11 Oct 2023 00:00:00 +0000

Communication between scientists and policymakers is critical for developing effective policies grounded in scientific evidence. However, actual communication between these two groups is often difficult, due to differences in training, communication styles, and motivation. While numerous “best practices” guides provide advice on science communication, many of these recommendations are based on personal experience rather than empirical data. To remedy this gap in the literature, researchers at the University of California, Davis conducted a literature review of scholarship on best practices in science communication, with an emphasis on finding reports based on empirical data rather than personal experience. The researchers synthesized their findings into a set of best practices for science communication and considered how scientific reputation affects engagement in the policy process.
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E-bike Incentive Programs Reduce GHGs and Support Recreational Travel

Mon, 7 Aug 2023 00:00:00 +0000

Local and state electric bike (e-bike) incentive programs offering point-of-sale or post-sale monetary discounts to consumers have been implemented across the United States since 2018. As yet, however, little is known about their effectiveness in changing travel behavior. To understand the outcomes of these incentive programs, UC Davis researchers analyzed survey data from rebate recipients in Northern California two months and one year after they acquired e-bikes. The rebate programs were evaluated for effects of e-bike ownership on travel behavior, including changes in bicycling, driving, and use of transit, and on greenhouse gas emissions. The team also suggest areas for future research.
View the NCST Project Webpage

New Tool for Gig Drivers Considering Going Electric

Wed, 2 Aug 2023 00:00:00 +0000

Gig drivers who use their own vehicles to provide transportation and food delivery services face barriers to electric vehicle (EV) adoption including costs, access, and information. To move toward a sustainable transportation future, California is advancing regulations to accelerate electrification of high-mileage vehicles, such as those driven by gig workers for transportation network companies (TNCs) like Uber and Lyft. By 2030, the state istargeting 90% of passenger miles traveled on TNCs to be fueled by electricity. To support this objective, UC Davis researchers developed an online tool to help gig drivers understand their potential cost savings from EVs. This research brief summarizes the findings from that research and provides policy implications.
View the NCST Project Webpage

Do Slow Streets Encourage More Dockless Travel? Evidence from Electric Scooter Usage in Four Cities

Wed, 2 Aug 2023 00:00:00 +0000

In the early stages of the COVID-19 pandemic, many cities across the US reallocated street spaces for active transportation such as walking, bicycling, and scootering, including by electric bikes and scooters. Slow Streets, projects that limit through-traffic access for motor vehicles to provide a safer space for other travelers, were implemented at an unprecedented speed and scale. This analysis of pandemic-era Slow Street dockless electric scooter (e-scooter) use offers insights that may assist decisionmakers. A research team at the University of Southern California collaborated with Lime, an e-scooter company, to analyze Slow Streets programs in the cities of Oakland, San Francisco, Los Angeles, and Portland. Using two statistical approaches, they examined dockless e-scooter travel at four different times of day and overall weekly and monthly averages of dockless e-scooter trips. This policy brief summarizes the findings from that research and provides policy implications.

Land Use Efficiency Tool Improvements May Help Governments Meet Sustainability Targets Equitably

Mon, 31 Jul 2023 00:00:00 +0000

A variety of web-based mapping and quantitative analysis tools can help planners evaluate whether a given land use efficiency strategy can meet goals, but there has been limited information about the coverage, breadth, and availability of these tools. These tools can assist in the regional implementation of greenhouse gas reduction strategies through land use development. As such, decisionmakers would benefit from knowing which of these tools could serve their needs. Researchers at UC Davis studied methods and tools available to regional and local governments to evaluate the land use efficiency and equity of their policies and plans. The research team then conducted a workshop with regional and local government representatives to identify efficacy, gaps, and potential improvements for these tools.
View the NCST Project Webpage

US-Mexico Second-hand Vehicle Trade: Implications for responsible EV end of life management and material circularity in North America

Thu, 13 Apr 2023 00:00:00 +0000
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...

Community-Oriented Solutions May Help Rural Residents Adapt to Life Without a Car

Sun, 2 Apr 2023 00:00:00 +0000

Rural residents face significant mobility challenges because travel destinations are far, opportunities like jobs and access to essential needs are limited, and rural roadways are more dangerous than their urban counterparts. These challenges are exacerbated when households have limited or no access to a vehicle because other transportation options are often expensive, inconvenient, or nonexistent. The confluence of not having access to a vehicle and living in rural areas is often associated with increased social isolation and difficulties in conducting basic activities like grocery shopping and accessing health care. Researchers at UC Davis used US Census microdata to describe socioeconomic and mobility characteristics of carless households and residents in rural California and conducted interviews to understand the barriers to access and travel adaptations among individuals who have limited access to a vehicle.
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Flexible Routing for Ridesharing

Wed, 22 Mar 2023 00:00:00 +0000

Traffic congestion is a significant problem in major metropolitan areas in the United States. According to the Urban Mobility Report, in 2019 commuters on average lost about 54 hours in traffic congestion. To combat this, major infrastructure projects have been undertaken. However, expansion projects cannot keep up with the increase in usage of personal vehicles and thus fail to address the traffic congestion problem. Carpool ridesharing has shown some promise in combatting this traffic congestion problem. In this system, the drivers are regular commuters who take detours to pick up and drop off passengers to decrease their transportation costs. This system increases the efficiency of the transportation system by providing flexible commutes to people, thus reducing the need for each commuter to use their own personal vehicle. The researchers developed three approaches to rideshare routing. The researchers conducted a computational study using a San Francisco taxicab dataset...

Updating the Induced Travel Calculator

Fri, 3 Feb 2023 00:00:00 +0000

Expanding roadway capacity often leads to commensurate increases vehicle miles traveled (VMT). This is the “induced travel” effect—a net increase in VMT across the roadway network due to an increase in roadway capacity. This increase in VMT erodes any initial reduction in congestion and causes increased greenhouse gas and local air pollutant emissions. Yet highway expansion projects continue to be proposed across the US, often using congestion relief—and sometimes greenhouse gas reductions— as a justification for adding lanes. The existence of these rosy projections about highway expansion projects indicates that the induced travel effect is often not fully accounted for in travel demand models or in the environmental review process for the projects, as prior research has shown.1 With these problems in mind, researchers at the University of California, Davis developed and launched an online tool in 2019—the NCST Induced Travel Calculator—to help agencies estimate the VMT induced...

Increasing Highway Capacity Induces More Auto Travel

Fri, 3 Feb 2023 00:00:00 +0000

Building additional roadway capacity—via constructing entirely new roadways or extending or adding lanes to existing roadways—is often proposed as a solution to traffic congestion and even as a way to reduce greenhouse gas (GHG) emissions. The logic for the latter is that increasing roadway capacity increases average vehicle speeds, which improves vehicle fuel efficiency and reduces per-mile emissions of GHGs and local air pollutants. But that logic relies on the flawed assumption that the amount that people drive does not change when the time it takes to drive places changes. In fact, the amount that people drive does respond to changes in driving times. Empirical research demonstrates that as roadway supply increases, vehicle miles traveled (VMT) generally does, too. This is the “induced travel” effect—a net increase in VMT across the roadway network due to an increase in roadway capacity, which ultimately erodes any initial increases in travel speeds and causes increased...

Travel Behavior Trends During the COVID-19 Pandemic

Fri, 30 Sep 2022 00:00:00 +0000

The proliferation of digital devices and online services over the past decades has changed how people travel, enabling new mobility options and offering greater opportunities for e-commerce and telework. Researchers are still trying to understand how these new technologies and emerging transportation services are being adopted by different socio-demographic groups, and what the current trends might mean for transportation sustainability. In 2019, researchers at UC Davis launched a national survey to gain insights on general travel behaviors and the adoption of various emerging technologies. The researchers looked at behaviors such as the adoption of smartphones and information and communication technology, telecommuting, new mobility options, electric vehicles, and other alternative-fuel vehicles. With the onset of the COVID-19 pandemic in early 2020, the researchers modified their plan to understand new trends, such as increased remote work, online/virtual meetings, and...

How Intelligent Vehicle Technologies Can Improve Vulnerable Road User Safety at Signalized Intersections

Thu, 25 Aug 2022 00:00:00 +0000

Motor vehicle crashes are the leading cause of accidental deaths in the US. In 2020, 38,824 people lost their lives in car-related crashes. Bicyclists and pedestrians are particularly susceptible—7,448 of these “vulnerable road users” were killed nationwide in 2020, and 29% of all reported crash-related fatalities in California were vulnerable road users. A variety of intelligent vehicle technologies hold promise for improving bicycle and pedestrian safety. Sensors in vehicles and/or used by vulnerable road users themselves could alert travelers of potential conflicts, giving them more time to react. However, these technologies all have unique technical, operational, and financial characteristics, and they might perform differently in different environmental conditions and at different levels of deployment. Little research has been done on how these technologies might affect safety. Researchers at the University of California, Davis combined aggregate historical crash data...

Demonstrating the Life Cycle Assessment Framework for Complete Streets

Tue, 16 Aug 2022 00:00:00 +0000

“Complete streets” are those designed not only to accommodate private vehicles, but also to enable safe access for all users, including pedestrians, bicyclists, and transit riders of all ages and abilities. Complete streets can contribute to increased transportation choices, economic revitalization, improved return on infrastructure investments, livable communities, improved safety, improved public health through promotion of active transportation, greenhouse gas reductions, and improved air quality. In 2018, researchers developed a life cycle assessment (LCA) framework for complete streets to enable planners and policymakers to quantify environmental and social impacts over the life cycle of a complete streets project. In this follow-on project, the researchers applied the framework to three case studies covering urban, suburban and rural/suburban regions/conditions. The researchers assessed whether the LCA framework was useful in identifying whether a complete...

Planning Can Maximize Benefits and Mitigate Negative Consequences of Future Travel Increases from E-Commerce

Tue, 16 Aug 2022 00:00:00 +0000

Last-mile delivery, in which companies deliver goods to the end consumers, is one of the costliest segments of the supply chain and can generate significant emissions. The demand for last-mile delivery has grown in recent decades because of the emergence of e-commerce, which has reshaped consumer behavior and how companies distribute goods. E-commerce has consistently been growing for more than a decade, and growth intensified during the COVID-19 pandemic. Although e-commerce is still in a fast growth phase, there is little understanding about how much it will grow, how it will impact the transportation system, and how these impacts might differ geographically. Researchers at the University of California, Davis developed a forecasting model to quantify the potential impacts of future e-commerce on emissions and transport activity under different scenarios with assumptions about penetration levels of various technologies (e.g., electrification, rush deliveries, crowdshipping,...

Incentive Systems for New Mobility Services to Reduce Congestion

Tue, 9 Aug 2022 00:00:00 +0000

With rapid population growth and urban development, traffic congestion has become an inescapable issue. Future mobility services may offer a new and very effective opportunity to incentivize congestion-reducing behavior. Ridesourcing, food delivery, and package delivery companies make decisions that directly or indirectly affect routing for an increasing number of drivers. These organizations have more flexibility and more power to affect traffic, and targeting them with incentives may be more efficient than incentivizing individual drivers.
Motivated by this idea, researchers at the University of Southern California developed a distributed algorithm for offering incentives to organizations to make socially optimal routing decisions. The algorithm is designed to lower the traffic flow of congested roads without creating new congestion in other parts of the road network. This policy brief summarizes the findings from that research and provides research implications.

Understanding the Bike-share Market in the Sacramento Region to Increase Demand and Improve Access

Fri, 5 Aug 2022 00:00:00 +0000

Bike-share services provide an affordable and environmentally sustainable transportation option. Research has shown that bike-share use can reduce car dependence and facilitate access to public transit. Expanding the use of these services can help cities meet environmental goals and, if done right, better serve transportation-disadvantaged residents. Researchers at the University of California, Davis surveyed households and bike-share users in the Sacramento region and used both behavioral modeling and market segmentation approaches to identify opportunities for increasing demand while improving access for low-income groups. The results can inform cities’ efforts to expand bike-share services.
View the NCST Project Webpage

Advancing Seaport Environmental Sustainability: Case Studies from the San Pedro Bay Ports Clean Air Action Plan

Wed, 20 Jul 2022 00:00:00 +0000

The Port of Los Angeles and Port of Long Beach, together referred to as the San Pedro Bay Port Complex, are an important source of regional economic activity in southern California. However, the port complex is also the single largest fixed source of air pollution in the region. In response to pressure from regulatory agencies and local communities, the two ports developed a Clean Air Action Plan in 2006.
The research team assembled three case studies of programs implemented under the Clean Air Action Plan: the Technology Advancement Program, voluntary Vessel Speed Reduction programs, and the Clean Trucks Program. An additional case study featured a proposed private-sector infrastructure project: the Southern California International Gateway project. Each case study describes the program, stakeholders involved, barriers to implementation, and outcomes. These cases highlight the institutional challenges the ports face while working with a multitude of stakeholders and...

The Impact of Ridehailing on Other Travel Modes and on Vehicle Dependency

Tue, 12 Jul 2022 00:00:00 +0000

Emerging transportation services such as ridehailing, whose development and adoption have been enabled by information and communication technology, are transforming people’s travel and activity patterns. It is unclear what these changes mean for environmental sustainability, as researchers are still trying to understand how new mobility services might impact multimodal travel and reliance on private cars. A better understanding of emerging mobility patterns can improve travel demand forecasting tools, inform investment decisions, and help provide efficient, reliable, and accessible transportation solutions.
Building on a multi-year study, researchers at the University of California, Davis surveyed 4,071 California residents in 2018 about their personal attitudes and preferences, lifestyles, travel patterns, vehicle ownership, adoption and use of new mobility services, and personal and household characteristics. This brief summarizes the results of multiple studies that...

The Costs of Owning Battery-Electric Trucks – Is the Research Aligning?

Thu, 23 Jun 2022 00:00:00 +0000

California and other states are pursuing strategies to transition to zero-emission passenger vehicles and trucks, and regulations under development in California will shape multiple states’ transition to zero-emission medium- and heavy-duty trucks. A key factor influencing the pace of these regulations and complementary incentive programs is when battery-electric trucks can be expected to reach cost parity with conventional diesel trucks. Studies on likely purchase cost and total cost of ownership of battery-electric trucks have produced different estimates about these trucks’ current and future competitiveness with diesel trucks. Comparing these studies, their assumptions, and their total cost of ownership estimates can ultimately help policymakers understand the financial impacts fleets will experience in transitioning to zero-emission vehicles, and the likelihood of fleets purchasing zero-emission vehicles independent of regulatory requirements.
Researchers at the...

Evaluating Pilot Approaches to Increase Rural Mobility

Thu, 26 May 2022 00:00:00 +0000

People who live in rural areas in California face unique transportation challenges due to long travel distances, infrequent transit service, the cost of car ownership, and limited access to app-based rideshare services that are common in more populated urban centers. Over the past eight years, UC Davis has partnered with the eight San Joaquin Valley Metropolitan Planning Organizations to identify and support development of three innovative mobility pilot concepts for the region.
Researchers at the University of California, Davis evaluated these three pilot programs using survey and service usage data collected from their launch dates in 2019 and 2020 through November 2021 to understand the participant characteristics and outcomes of each pilot. This policy brief summarizes the key findings from that research.
View the NCST Project Webpage

Real-World Brake Activity Testing in Heavy-Duty Vehicles to Inform Emissions Inventories

Thu, 26 May 2022 00:00:00 +0000

Studies have shown that long-term exposure to ambient air pollution endangers human health. Regulations targeting internal combustion engines have proven effective in reducing their particulate matter (PM) emissions over the years. However, PM from non-tailpipe sources such as brake and tire wear are not currently regulated and are expected to eventually become the dominant source of traffic-related PM emissions. Although studies have produced a greater understanding of brake wear, laboratory tests are an imperfect substitute for real-world activity. Therefore, it is necessary to investigate brake activity for diverse vehicle classes and sizes under in-use conditions.
Researchers at the University of California, Riverside aimed to establish a test method to determine brake activity of a heavy-duty vehicle under both dynamometer tests and on-road tests. The results advance the research methodology, ultimately contributing to a more accurate determination of brake activity...

Variable Speed Limit Control to Reduce Traffic Congestion in the Face of Uncertainty

Thu, 26 May 2022 00:00:00 +0000

Highway bottlenecks caused by traffic incidents, lane drop, ramp merging or slow vehicles negatively impact traffic mobility and safety. Traffic regulation techniques, such as adjusting speed limits, providing lane-change recommendations, and restricting on-ramp vehicle inputs with traffic signals in response to an incident, have been found to mitigate congestion from these types of bottlenecks. However, most existing research assumes that traffic models and measured traffic data are accurate and that vehicle drivers always comply with recommendations from the infrastructure. These assumptions are rarely true in the real world and can lead to inconsistencies between the theoretical benefits and the actual benefits obtained in field tests.
Researchers at the University of Southern California developed, analyzed, and evaluated an innovative approach to alleviate highway bottleneck congestion. The approach includes issuing variable-speed advisories and lane-change recommendations...

Grid Energy Storage Assessment for Select Vehicle Electrification Scenarios

Mon, 23 May 2022 00:00:00 +0000

California has set aggressive vehicle electrification goals to achieve its greenhouse gas (GHG) reduction targets. The state is also integrating renewable energy into the electric grid under the Renewables Portfolio Standard (RPS). Increasing electricity demand from electric vehicles, combined with increasing power generation from variable renewable energy sources like solar and wind, will require significantly increased electrical energy storage capabilities, such as batteries and pumped hydroelectric storage. Assessing long-term energy storage needs and deploying the necessary infrastructure will be critical for maintaining future grid reliability.
Researchers at the University of California, Riverside analyzed several scenarios using the California Public Utilities Commission’s Resolve power system planning model to understand how vehicle electrification, renewable energy standards, and GHG reduction goals affect California’s mid- to long-term energy storage needs. This...

A Glimpse of Microtransit at an Early Stage: The SmaRT Ride Consumer Market in the Sacramento Area

Tue, 3 May 2022 00:00:00 +0000

Microtransit is a new, technology-enabled, on-demand transportation mode in which small shuttles provide shared rides through flexible routing and scheduling in response to customers’ requests for rides. It can potentially offer greater efficiency and more equitable service than ride-hailing services, and it may fill gaps in traditional transit services. Thus far, the early shape of the microtransit customer market remains unclear. Specifically, why some people are interested in microtransit while others are not remains an open question. For people who have never used it, what factors could work as facilitators or barriers in their willingness to adopt microtransit? Who are early adopters of microtransit? Aiming to fill this gap, in 2021, researchers at the University of California, Davis conducted focus groups and an online survey of SmaRT Ride adopters and users of other means of transportation in the Sacramento area.
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The Requirements, Costs, and Benefits of Providing Charging Infrastructure for Heavy-Duty Electric Trucks at California’s Rest Areas

Fri, 15 Apr 2022 00:00:00 +0000

California’s Advanced Clean Trucks regulation requires sales of zero-emission tractor-trailer trucks starting in 2024, increasing to 30% by 2030. Since most of these trucks will travel predominantly on the state’s major highways, a robust network of battery charging infrastructure will be needed along these routes. The California Department of Transportation (Caltrans) maintains an extensive series of roadside rest areas throughout the state that are widely used by long-haul trucks. Providing charging at roadside rest areas, especially those along interstate highways, could help meet the needs of battery-electric tractortrailer trucks making multi-day trips. Thus, Caltrans should consider becoming involved with the establishment of battery charging facilities at its rest areas.
Researchers at the University of California, Davis assessed the possibilities for and barriers to providing charging infrastructure for heavy-duty, long-haul trucks at rest areas in California....

What to Make of Biofuels? Understanding the Market from 2010 to the Present, and Projecting Ahead to 2030 Given Current Policies

Wed, 6 Apr 2022 00:00:00 +0000
Low-carbon biofuels are projected to play a critical role in the early and middle stages of a transition away from petroleum fuels, and they will likely have a longer-term role in uses like aviation and maritime transportation that require energy-dense fuels in high volumes. Policies over the last decade aimed to move low-carbon biofuels squarely into U.S. markets. While these policies encouraged the production of conventional biofuels such as crop-based ethanol, cellulosic fuels that can have a significantly lower carbon footprint per unit energy failed to materialize at commercial scale. A research team at the University of California, Davis examined the track record of the past decade for clues as to why this happened, and looked forward to 2030 to point to how current policies are likely to still fall short in delivering low-carbon biofuels that can reach scales needed for these hard-to-decarbonize sectors. The findings highlight barriers to low-carbon biofuel development...

Future Connected and Automated Vehicle Adoption Will Likely Increase Car Dependence and Reduce Transit Use without Policy Intervention

Sat, 2 Apr 2022 00:00:00 +0000

California sits at the epicenter of self-driving vehicle technology development, with numerous companies testing connected and automated vehicles (CAVs) in the state. CAVs have the potential to improve safety and increase mobility for children, the elderly, and people with disabilities. These vehicles will operate more efficiently, use less space on the roadway, and cause fewer crashes, all of which are expected to relieve traffic congestion. However, CAVs will also likely bring about complex changes to travel demand, urban design, and land use. The degree to which these changes will affect vehicle miles traveled, energy use, and air pollution in California is unknown and could have wideranging implications for the state’s ability to meet its climate goals.
Researchers at the University of California, Davis investigated the range of potential impacts that rapid adoption of CAVs in California might have on vehicle miles traveled and emissions. The researchers estimated...

A Model for Efficiently Allocating Resources to Mitigate Wildfire Risk along California Roadways

Thu, 24 Mar 2022 00:00:00 +0000

A key function of a highway network is to maintain access during normal and emergency operations. During wildfire evacuations, first-responders and firefighters depend on highways and local roads for transporting heavy equipment to communities in need. The California Department of Transportation (Caltrans) is expanding vegetation management to begin establishing defensible space zones along California’s nearly 16,000 miles of state highways and in about 230,000 acres of highway right-ofway. However, extended drought, a longer fire season, and higher temperatures brought on by climate change, along with the spread of invasive weeds and dense, dry vegetation, have created new challenges.
The California Department of Forestry and Fire Protection produced a Community Wildfire Prevention and Mitigation Report in 2019 with a methodology to assess wildfire risk. Caltrans and researchers at the University of California, Davis applied these methods to develop a highway-segment-specific...

Do Dock-based and Dockless Bikesharing Systems Provide Equitable Access for Disadvantaged Communities?

Tue, 22 Mar 2022 00:00:00 +0000

Bikeshare is an increasingly prevalent transportation option that offers users access to a bicycle without owning it. Both dockbased (requiring users to return bicycles to a fixed station) and dockless (free-floating) services have grown significantly over the past decade. Previous research has found that a well-designed bikeshare system has great potential to improve accessibility for disadvantaged communities. However, systems currently underserve these communities. Moreover, there is a lack of research about the performance and impacts of dock-based versus dockless bikeshare systems in terms of providing equitable access to disadvantaged communities.
Researchers at the University of California, Davis analyzed the difference in service levels among dock-based and dockless systems in the cities of San Francisco and Los Angeles. The researchers analyzed the spatial distribution of service areas, availability of bikes and bike idle times, trip statistics, rebalancing,...

A Truck Routing Model to Reduce Fuel Consumption and Emissions while Accounting for Parking Availability and Working Hours Constraints

Tue, 22 Mar 2022 00:00:00 +0000

The transportation sector is responsible for 28% of US greenhouse emissions, with a considerable amount being generated by medium- and heavy-duty trucks. Multiple strategies will be needed to improve efficiency and reduce carbon dioxide (CO2) emissions in the trucking industry. Researchers at the University of Southern California developed a truck routing model that minimizes fuel consumption and reduces emissions while explicitly accounting for parking availability and hours-of-service constraints. The researchers used the model to test various scenarios that reflect the practical constraints faced by drivers.
View the NCST Project Webpage

Single-Family Neighborhoods in Sacramento Have Sufficient Parking to Accommodate Accessory Dwelling Units

Mon, 14 Mar 2022 00:00:00 +0000

Accessory dwelling units (ADUs) are small, self-contained housing units that share the same lot as a primary dwelling, usually a single-family detached house. In places with major housing shortages ADUs can be an efficient and cost-effective way to increase supply. Over the last few years, the California Legislature has passed laws to reduce barriers to permitting ADUs, and some California cities have liberalized their regulations even further. However, loosening ADU regulations—particularly those related to parking—can spark neighborhood opposition to ADUs. Recent surveys indicate that both homeowners and local government staff remain concerned that ADUs will overwhelm neighborhood parking supplies.
Whether these concerns are justified is unclear. A UC Davis-led research team surveyed 396 homeowners in Sacramento and collected lot size and other data to investigate whether the total effective parking supply of the average single-family detached home is sufficient to...

What Will a Transition to Digital Transit Payments Mean for Un- and Underbanked Transit Passengers?

Fri, 11 Mar 2022 00:00:00 +0000

The more than 350 transit agencies in California currently offer a patchwork of payment options, including cash, contactless payments, and a multitude of agency-issued cards. This inconsistency across transit operators acts as a barrier to the use of public transit. The California Integrated Travel Project (Cal-ITP) was established in 2018 to create an integrated, statewide payment system to make travel simpler and more cost-effective. Cal-ITP is pursuing open-loop payment systems, which offer a suite of digital payment options such as credit and debit cards, prepaid debit cards, app-based wallet systems, and peer- to-peer payment apps.
However, questions remain about whether open-loop payment systems would accommodate all travelers, particularly those who are unbanked (i.e., do not have a bank account) or underbanked (i.e., have only a savings or checking account, but not both) and typically rely on cash. Researchers at the University of California, Davis partnered with...

How Much Do Local Climate Action Plans in California Consider Emissions, Cost, and Equity?

Fri, 11 Mar 2022 00:00:00 +0000

Spurred in part by state-level climate policies, California cities and counties have released climate action plans (CAPs) over the last decade to set emissions reduction targets and outline actions that will help meet those goals. However, the state provides little guidance to jurisdictions on how to produce these plans. The range of information included in CAPs varies dramatically across jurisdictions. Additionally, little is known about how jurisdictions transition from the planning to the implementation phase of climate action, or what major factors influence their decision-making process. Other state laws promote emissions reductions in disadvantaged communities, highlighting the importance of making equity a key consideration in CAPs.
Researchers at the University of California, Davis assessed and scored over 30 CAPs released between 2009 and 2020 based on the degree to which they addressed three themes: emissions reductions, cost, and equity. The researchers also...

Simulating the Effects of Shared Automated Vehicles and Benefits to Low-Income Communities in Los Angeles

Tue, 22 Feb 2022 00:00:00 +0000

Studies show that automated vehicles are likely to increase vehicle travel, resulting in more congestion and greenhouse gas emissions (GHGs). Pricing policies such as increasing the cost of driving and reducing the cost of alternative travel modes could lessen the negative impacts of automated vehicle deployment, although it is unclear to what extent. Cities located in the Westside Cities Council of Governments planning area in western Los Angeles County could be candidates for early deployment of automated vehicles because of their high travel volumes, well-maintained roads, and temperate weather conditions. Los Angeles County also faces high levels of poverty. Thus, the Westside Cities area presents an important opportunity to study how automated vehicles and associated pricing policies might affect congestion, vehicle miles traveled (VMT), and GHGs, and whether they might improve mobility for marginalized populations.
Researchers at the University of California, Davis...

BikewaySim and Complete Paths Networks are Expected to Improve Modeling of Bicycle Activity and Route Choice

Fri, 18 Feb 2022 00:00:00 +0000

Many cities are focused on increasing bicycle use through development of infrastructure such as bicycle lanes and multi-use paths. Traditionally, travel demand models (TDMs) are used to evaluate the demand for (and impact of) proposed transportation projects. However, the vast majority of TDMs cannot be used to evaluate the impact of bicycle projects. Improved TDMs are needed to help estimate the impacts of new bicycle projects on cycling activity and prioritize the construction of the most beneficial bicycle projects with limited transportation department resources.
To more accurately model bicycle travel, preference-based route assignments are needed. Researchers at the Georgia Institute of Technology created a semi-automated process for developing an all-streets network to be used in TDM applications. The researchers combined detailed roadway characteristic information from three different transportation networks in GIS shapefile format and used BikewaySim, Georgia...

Publicly Funded Electric Carsharing Services Can Reduce Emissions and Expand Transportation Access, but They Need More Study

Fri, 11 Feb 2022 00:00:00 +0000

Carsharing, in which members have access to a network of shared vehicles for short-term rentals, has existed in the US for more than two decades. Within the last six years though, carsharing services have proliferated under a wider variety of business models. These programs are increasingly seen as a means of increasing transportation access in underserved communities—particularly in those with limited public transit service. The recent incorporation of electric vehicles in carsharing programs is also seen as a promising public policy for reducing greenhouse gas emissions. Government support for carsharing has accelerated, with state and federal agencies investing millions of dollars in support of equity and sustainability goals.
As funding grows, it becomes increasingly important to learn from carsharing services that have already been implemented. Researchers at the University of California, Davis and the non-profit organization Mobility Development reviewed evaluations...

A Roadmap for Integrating Complete Streets Infrastructure into Pavement Asset Management Systems

Fri, 21 Jan 2022 00:00:00 +0000

Transportation agencies nationwide use pavement management systems (PMS) to maintain roads and highways. Pavement management has typically been used for auto-oriented infrastructure. However, state and local agencies are increasingly adopting complete streets policies to promote roadway designs focused on the needs of all transportation users. Complete streets designs include new assets such as pedestrian and bicycling infrastructure that are not typically incorporated into mainstream pavement management systems and do not have asset management systems of their own. Including pedestrian and bicycling features into asset management systems (directly in PMS or via other approaches) would help ensure that sidewalks and bike lanes are properly maintained over time and continue to provide the safety, environmental, and public health benefits attributed to complete streets design. Researchers at the Georgia Institute of Technology and the University of California, Davis surveyed...

Urban Design that Reduces Vehicle Miles Traveled Can Create Economic Benefits

Mon, 10 Jan 2022 00:00:00 +0000

Practitioners and scholars have traditionally held the view that building transportation infrastructure, such as highways that facilitate more driving, will improve economic development. Evidence for this view was derived from construction of new transportation networks such as the Interstate Highway System in the 1950s and 1960s that forged new regional connections and contributed to economic growth. But now, decades later, infrastructure improvements to a mature system have less-clear benefits and may simply shift economic activity around. More recently, as cities and regions have begun implementing policies to reduce vehicle miles traveled (VMT), the question of the economic role of less VMT has emerged. In many cases, higher economic performance is associated with walkable, pedestrian-oriented neighborhoods, designed in ways that reduce car travel.
Researchers at the University of Southern California reviewed the literature on property values, business sentiment,...

Expanding the UC Davis GIS Electric Vehicle Planning Toolbox Beyond California

Fri, 17 Dec 2021 00:00:00 +0000

Plug-in electric vehicles (EVs) are quickly moving to the broader consumer market. While the home is still the primary location for recharging these vehicles, public EV charging infrastructure at workplaces, public destinations, and along travel corridors will be critical for the continued market growth of EVs. Governments will need to ensure that sufficient charging infrastructure is available at these locations to meet future demand. Researchers at the University of California, Davis Plug-In Hybrid & Electric Vehicle Research Center previously developed a planning toolbox for public charging infrastructure based on data available in California. The toolbox is a user-friendly set of modeling tools that allows planners to anticipate the future geographic distribution of EVs and the resulting optimal locations of charging infrastructure. To date, however, the tools have only been applied in California contexts with California-specific data. For this project, the...

Do Travel Surveys Show that Californians Walked and Biked Less in 2017 than in 2012?

Tue, 14 Dec 2021 00:00:00 +0000

The California Department of Transportation set a goal of doubling walking and transit use and tripling bicycling in the state between 2010 and 2020. However, the most recent comprehensive travel surveys, the 2012 California Household Travel Survey (CHTS) and the California results from the 2017 National Household Travel Survey (NHTS), suggest that the state is moving in the wrong direction. These surveys seemed to show that a smaller share of trips were made by walking or biking in 2017 than in 2012, while private vehicle mode share increased. It is unclear whether the decline represents real changes stemming from various demographic or other factors or is instead related to methodological differences between the two surveys. Researchers at the University of California, Davis used the publicly available 2012 CHTS and 2017 NHTS California add-on data to examine the impact of methodological differences on the changes in mode shares over this five-year period and conducted a...

Material Efficiency as a Means to Lower Environmental Impacts from Concrete

Mon, 13 Dec 2021 00:00:00 +0000

Concrete is a key component of the built environment. However, the manufacture of cement-based materials, such as concrete, produces over 8% of worldwide anthropogenic greenhouse gas (GHG) emissions. While reducing impacts from material production is an important strategy, structural design can also mitigate the environmental impacts of concrete. Designing infrastructure in a manner that uses concrete more efficiently, and thus lowers consumption while meeting the same system demands, holds promise for reducing GHG emissions while avoiding unintended consequences. Researchers at the University of California, Davis developed an initial methodology to evaluate implications of design decisions on the environmental impacts of concrete systems using a multi-criteria selection process to assist decision-makers. They demonstrated the methodology with a case study evaluating a built Caltrans pavement overlay for which comparisons of the GHG emissions and costs of various design alternatives...

Quantifying Environmental Impacts from Concrete Production, While Accounting for Data Variability and Uncertainty

Mon, 13 Dec 2021 00:00:00 +0000

Concrete is the second most-used material on earth, surpassed only by water. Concrete is used in construction of roads, bridges, ports, and buildings. Concrete is also responsible for over 8% of annual anthropogenic greenhouse gas (GHG) emissions globally. As population and urbanization increase and existing infrastructure deteriorates, demand for production of concrete will increase, and with it, the environmental burdens from its production. The models used to determine environmental impacts of producing concrete have considerable uncertainty and variability. This makes it challenging to identify the most effective means of mitigating these burdens. These challenges are exacerbated by the fact that the key drivers for air pollutant emissions and GHG emissions vary. While many are linked to the energy resources used in the production of cement, there are also notable air pollutant emissions from quarrying practices. Improved understanding of the environmental impacts from...

Autonomous Vehicle Policies Must Be Flexible to Support Deployment in Rural Regions

Tue, 30 Nov 2021 00:00:00 +0000

Fully autonomous vehicles (AVs) hold the potential to significantly improve traffic safety, mobility and accessibility, and energy efficiency—longstanding challenges for rural transportation planning. Some of these benefits are inherent to automation and therefore achievable through private AV ownership, while other benefits can only be achieved if AVs are operated in a shared fleet through a carsharing model. AV benefits such as increased vehicle occupancy are only achieved if the AV is used for ridesharing. AVs may also significantly increase vehicle travel and associated environmental impacts. The magnitude of the changes in vehicle travel and environmental impact will depend to a significant degree on the extent to which AVs are available for individual ownership vs. carsharing or ridesharing. As a result, shared mobility is commonly cited as an important strategy for mitigating growth in vehicle travel. Most AV research to date has been done in an urban context. Changes...

Where Are Buyers of Used Electric Vehicles in California?

Mon, 22 Nov 2021 00:00:00 +0000

In the US, the market share of plug-in electric vehicles (PEVs)—including battery electric and plug-in hybrid electric vehicles—has been rapidly increasing as a variety of new PEVs have been introduced. Knowing where PEV users are located is important to ensure that electric vehicle charging infrastructure is installed in areas where it is needed. Information on PEV location can also inform electricity supply planning to prepare for a future with higher PEV adoption. Previous studies have looked at the spatial distribution of new PEVs but not of used PEVs. Yet these spatial distributions will likely differ because the buyers of used PEVs have different characteristics than new PEV buyers. Therefore, planning charging infrastructure and electricity supply based solely on new PEV data may not serve both new and used PEV buyers. Policies developed to support drivers of used PEVs may ultimately attract a broader group of people into the PEV market, as used vehicles are less...

Dynamic Routing to Improve the Efficiency of Ride-Sharing

Wed, 17 Nov 2021 00:00:00 +0000

Traffic congestion causes significant economic costs, wasted time, and public health risks. Ride-sharing, defined as a joint trip of more than two participants who share a vehicle that requires coordination among itineraries, has the potential to help mitigate congestion. A good ride-sharing system should provide quick response to passenger requests while identifying routes with minimum travel time. This is not an easy task, especially with dynamic passenger requests, variable request times, and cancelations of existing requests. One way to mitigate the effect of these uncertainties is to allow passengers to walk to a designated pick-up spot while waiting for the drivers, which can improve the system’s efficiency. Taking advantage of ride-sharing incentives such as High Occupancy Vehicle (HOV) lanes can also reduce travel time and make ride-sharing more appealing. Researchers at the University of Southern California developed a two-stage algorithm to solve the routing problem...

Expanded Workforce Development Opportunities are Needed for Transportation Sector Climate Adaptation Professionals

Tue, 26 Oct 2021 00:00:00 +0000

Early investments in climate change research, policy, and planning focused heavily on climate mitigation—efforts to reduce greenhouse gas emissions. Adaptation initiatives are essential to the resilience of the transportation system in the face of increasingly severe climate threats; the failure to adapt will result in repair and recovery efforts absorbing an ever-increasing share of limited transportation resources. The growing emphasis on climate adaptation has created a demand for professionals with a new, interdisciplinary skillset. However, the pathways for developing the skills and competencies for adaptation careers in the transportation field are not well established. The knowledge base for climate adaptation is changing rapidly and the climate adaptation process itself is inherently complex. Training and educational opportunities in climate adaptation are increasing, but remain relatively limited. To understand current climate adaptation workforce development needs,...

Failing Shopping Malls Can Be a Powerful Tool for Addressing California’s Affordable Housing Shortage

Mon, 27 Sep 2021 00:00:00 +0000

Declining sales and anchor store bankruptcies have led to a nationwide trend of shopping malls failing. This trend has accelerated during the COVID-19 pandemic, and market analysts estimate that several hundred malls are at risk of failing in the next five years. As malls close, the sites present tremendous redevelopment opportunities. While redevelopment plans may include new retail or other commercial options, housing is desperately needed in California— the state has an estimated shortage of 2.5– 3.5 million units—and former mall sites may offer a natural solution to the state’s housing woes. Redevelopment planning has already begun for some sites. Researchers at the University of Southern California looked at case studies of ten distressed malls in California’s metropolitan areas to assess their potential for mixed-use development, including housing. The case studies included malls with and without current redevelopment plans, and illustrate issues that could hinder or...

Costs, Reliability, Vehicle Characteristics, and Incentives are the Top Factors Influencing Freight Vehicle Technology Choices

Tue, 7 Sep 2021 00:00:00 +0000

California has set goals for transitioning the freight sector to near-zero-emission and zero-emission vehicles (ZEVs). California offers several incentive programs to encourage adoption of ZEVs, but purchase decisions are driven by complex factors beyond simple purchase price. Understanding the behaviors and attitudes of freight stakeholders toward ZEVs can inform the design of more effective incentive programs to meet California’s goals. Researchers at the University of California, Davis deployed a stated-preference survey of fleet and carrier companies to collect information about vehicle purchase preferences and how they might be influenced by various incentive programs. This policy brief summarizes the findings from that research and provides policy implications.
View the NCST Project Webpage

Curbside Management Is Critical for Minimizing Emissions and Congestion

Tue, 31 Aug 2021 00:00:00 +0000

The curbside is valuable real estate in cities, providing private vehicle parking, pick-up/drop-off areas, public transit stops, freight loading/unloading zones, and space for pedestrians and bicyclists. Shortages and poor management of curb space can cause congestion and increased emissions due to vehicles searching for parking and can create unsafe conditions from vehicles double parking. Traditional curbside planning strategies have relied on land use–based demand estimates to allocate access priority to the curb, such as pedestrian and transit in residential areas and commercial vehicles in commercial and industrial zones. Recently, pilots in San Francisco, Washington, D.C., and elsewhere have used new technologies to provide information to users about space availability or dynamically price the curb. Researchers at the University of California, Davis conducted a review of practices in curbside management, and they conducted simulations to evaluate the impact of different...

Exposure to Electric Vehicle Technology at Home and Work Can Fuel Market Growth

Mon, 23 Aug 2021 00:00:00 +0000

Sales of plug-in electric vehicles (PEVs), which include battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs), have grown substantially in recent years. To encourage PEV adoption, policymakers have offered monetary incentives for new PEV purchases, invested in charging infrastructure, and provided use-based incentives like High-Occupancy Vehicle (HOV) lane access and parking benefits. But questions remain regarding where, for how long, and how much promotion and government support might be necessary to achieve the state’s targets. Existing research on technology diffusion indicates that exposure through neighbors, workplace peers, and other acquaintances can legitimize new technology for the mass market and accelerate its market penetration. Researchers from the University of California, Davis and Irvine examined the adoption of PEVs in California between 2014 and 2016, both spatially and temporally, to gain a better understanding of the technology...

Setting Transportation Network Company Policies to Increase Sustainability

Fri, 20 Aug 2021 00:00:00 +0000

Use of Transportation Network Companies (TNCs) such as Uber and Lyft has grown rapidly in cities across the United States. TNCs often provide a cheaper and more flexible travel option than traditional taxi services, and could improve transportation sustainability if they facilitated more pooled travel and public transit use. However, TNCs’ growth has been linked to increased congestion and emissions. Cities and states have begun regulating TNCs, imposing taxes that are assessed per ride at a flat or percentage rate. Researchers at the University of California, Davis assessed 21 state and local TNC taxes across the United States and developed a method of comparing per-ride and percentage taxes. The researchers then assessed the likelihood of these taxes encouraging more sustainable travel. This policy brief summarizes the findings from that research and provides policy implications.
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Across Early Policy and Market Contexts, Women and Men Show Similar Interest in Electric Vehicles

Tue, 10 Aug 2021 00:00:00 +0000

The transition to electric vehicles (EVs) will rely, ultimately, on the participation of all vehicle buyers. While nearly equal numbers of new vehicles are purchased by men and women, to date EVs are being acquired by far more men than women. Prior analysis of data from California at the end of 2014 found no difference between women and men in prospective interest in EVs; similar percentages were interested in an EV being the next new vehicle for their household. Yet today—years after these results were reported—the gender disparity in EV sales and registrations persists.
Researchers at the University of California, Davis examined whether the gender similarities in prospective interest in EVs witnessed in California extended to other states that, while generally supportive of California’s EV goals and signatories to many of California’s air quality standards had less supportive policy frameworks, fewer EV sales, and less EV charging infrastructure in 2014. The researchers...

Telecommuting Rates During the Pandemic Differ by Job Type, Income, and Gender

Fri, 9 Jul 2021 00:00:00 +0000

The onset of the COVID-19 pandemic caused massive travel disruptions across the country. Many people nationwide shifted to telework following stay-at-home orders, while those providing essential operations and services continued to travel to work. The pandemic’s impacts on travel behavior have complex environmental and equity implications. Telecommuting can be a means of decreasing vehicle miles traveled and greenhouse gas emissions associated with commuter travel and can reduce congestion during peak times. However, not all jobs can be performed from home. Policymakers and regulators who are considering policies to encourage telecommuting to achieve greenhouse gas reduction goals need to consider potential inequities that may arise or be intensified by these policies.
Researchers at the University of California, Davis examined the impacts of the COVID-19 pandemic on telecommuting patterns among various socio-demographic groups in the United States. During the early...

Congestion Reduction via Personalized Incentives

Thu, 8 Jul 2021 00:00:00 +0000

Rapid population growth and development in cities across the globe have fueled an inescapable urban burden: traffic congestion. Congestion causes huge economic losses and increased vehicle emissions, which contribute to poor air quality. Over the past several decades traffic engineers have tried various strategies to reduce congestion, ranging from increasing roadway capacity to transportation demand management programs.
An alternative travel demand management approach that has garnered less attention is the use of positive incentive programs— rewarding desirable behavior rather than penalizing undesirable behavior—to reduce congestion. Researchers at the University of Southern California developed a real-time, distributed algorithm for offering personalized incentives to individual drivers to make socially optimal routing decisions. The methodology relies on online and historical traffic data as well as individual preferences and routing options from drivers’ origins...

Cost of Vehicle Ownership: Cost Parity Between Plug-in Electric Vehicles and Conventional Vehicles Is at Least a Decade Away

Tue, 6 Jul 2021 00:00:00 +0000

While plug-in electric vehicle (PEV) adoption has been rising over the past decade, with PEVs making-up about 7.8% of California’s new vehicle sales in 2019, the trend needs to quickly accelerate for the state to reach its goals of 100% zero-emission vehicle (ZEV) sales by 2035 and a zero-carbon economy by 2045. California has various incentive programs to encourage PEV adoption, but policymakers expect to phase these incentives out as PEVs reach cost parity with conventional internal combustion engine vehicles. Comparing the total cost of ownership—purchase price, operational costs, and resale value—of PEVs or other ZEVs with that of conventional vehicles can inform policy decisions about incentive programs and inform consumers’ purchase decisions, by accounting for PEVs’ higher purchase prices but lower fuel and maintenance costs.
Recent research has estimated that cost parity between PEVs and conventional vehicles will be achieved over the next decade. However, the...

Millennial Travelers Are More Multimodal than Older Travelers, but This Trend Might Change as They Age

Fri, 2 Jul 2021 00:00:00 +0000

Millennials, those who were born between the early 1980s and the late 1990s, tend to have different travel patterns than the members of the preceding generations when they were at the same age. Among various dimensions of millennial travel, multimodality—the use of multiple travel modes— has important implications for transportation sustainability. Prior research has found that members of this generation travel more by walking, bicycling, and riding public transit. Further, multimodal travelers are usually better informed about and more sensitive to level-of-service attributes of various modes than are habitual users of single modes (especially cars). Therefore, exploring trends in multimodality among millennials could inform policymakers’ efforts to encourage more sustainable travel modes for millennials and shed light on how they might respond to policy interventions.
Researchers at the University of California, Davis, compared millennials’ travel behavior to that of...

Ridehailing Demand Is Resilient Among Low-Income Travelers During the COVID-19 Pandemic

Wed, 30 Jun 2021 00:00:00 +0000

The COVID-19 pandemic has caused major shifts in the use of various means of travel, including ridehailing services (e.g., Uber or Lyft). Downward trends in ridehailing unsurprisingly emerged as lockdown orders reduced overall travel. The shock to the ridehailing industry came as the industry was experiencing considerable growth and facing increased regulatory control. Researchers at the University of California, Davis, examined how the COVID-19 pandemic has impacted the use of ridehailing and other travel behaviors among various sociodemographic groups. They conducted surveys prior to and during the early stages of the 2020 COVID-19 pandemic to measure changes in household activities, personal preferences, and travel patterns. The findings discussed in this policy brief are based on the analysis of the information provided by 1,274 respondents who participated in the survey both before the pandemic (2018- 2019) and during the early stage of the pandemic (spring 2020).

Instantaneous Hybridization Factor: New Metric to More Accurately Model Hybrid-Electric Vehicle Emissions

Wed, 2 Jun 2021 00:00:00 +0000

Hybrid-electric vehicles are a growing segment of the vehicle market and their share is anticipated to continue to grow as automakers seek to comply with increasingly stringent fuel economy standards. Hybrid vehicles generally use less fuel and produce fewer associated emissions than their conventional counterparts. However, their emissions patterns are unique; hybrids produce zero emissions during certain operations when the internal combustion engine is off, but produce particulate emission spikes when the engine starts or restarts. The overall air quality implications of more hybrid vehicles on the roads are not well understood.
Researchers at the University of Vermont collected real-time emissions and performance data from a hybrid vehicle operating in a variety of on-road conditions to develop a new parameter that could serve as the basis for future hybrid vehicle emissions models: the instantaneous hybridization factor. This parameter is the real-time proportion...

Why are Some California Consumers Abandoning Electric Vehicle Ownership?

Wed, 26 May 2021 00:00:00 +0000

California has set an ambitious goal of 100% zero-emission vehicle sales by 2035. Most consumer research to date has focused on understanding the factors influencing the initial purchase of plug-in electric vehicles (PEVs). But for the market introduction of PEVs, which include both battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs), to be successful, subsequent vehicle purchases by initial adopters need to continue to be PEVs rather than conventional vehicles. Discontinuance, the act of abandoning a new technology after once being an adopter, could make achieving California’s goal more challenging.
Researchers at the University of California, Davis surveyed California PEV buyers two to seven years after they first purchased their electric vehicle to understand whether they have continued to choose PEVs with subsequent purchases, and if not, what factors may have led to their discontinuance of the technology. This policy brief summarizes the...

The Monetary and Non-Monetary Factors Influencing Travel Choices in an Automated, Shared, and Electric Vehicle Future

Fri, 7 May 2021 00:00:00 +0000
The transportation system is undergoing three revolutions: vehicle automation, electrification, and shared mobility. While these are still nascent trends, studies suggest that they could become ubiquitous in the coming decades. How these revolutionary changes transpire will have significant implications for transportation sustainability. A key factor will be whether autonomous vehicles are deployed as shared cars that serve many travelers such as in ridesourcing or ridehailing fleets, or as privately owned vehicles that could dramatically increase vehicle miles traveled and associated environmental impacts. To anticipate how these revolutions will affect future transportation, and to develop policy to shape that future, it is important to understand the various factors that influence individuals’ travel choices. These choices include whether to travel alone or with others, and whether to use a private vehicle or a shared one. Some of these factors are monetary, such as the cost...

Developing Markets for Clean Heavy-Duty Trucks in Short-Haul Applications

Fri, 7 May 2021 00:00:00 +0000

California is pursuing multiple policies to spur the transition to a cleaner heavy-duty vehicle fleet. Achieving these targets will require massive change in the heavy-duty short-haul industry, and many unanswered questions remain. How do battery-electric heavy-duty trucks compare to diesel in everyday short-haul operations? How much would it cost to transition to a zero-emission truck fleet, and who would pay?
To begin to answer these questions, researchers at the National Center for Sustainable Transportation conducted a comprehensive analysis of the potential for zero-emission or near-zero-emission heavy-duty trucks to be used in short-haul drayage services. The researchers considered operational, economic, and environmental impacts through simulation modeling, interviews, case studies, stated preference surveys, and cost-effectiveness analyses.
View the NCST...

The Sustainability of Alternative Last-Mile Delivery Strategies

Wed, 14 Apr 2021 00:00:00 +0000

In the last decade, e-commerce has grown substantially and transformed individual shopping behaviors. Most shopping activities—at least part of the search, if not the purchase itself—now involve an online component. This has consequently changed commodity flow and urban goods distribution. E-commerce has the potential to reduce the negative impacts of shopping on the environment by substituting individual shopping trips to stores using personal cars with optimized truck deliveries. However, shopping behavior is often more complex than this one-to-one substitution.
Additionally, e-retailers entice consumers with free shipping, free returns, same-day, one-hour or two-hour expedited deliveries, and more in a quest for increased market share. These enhanced services result in additional distances driven, emissions, and operational costs for the e-retailer. The increasing customer expectations around lead time, delivery time, and return policy present a need for more sustainable...

Can Complete Streets Deliver on Sustainability?

Wed, 14 Apr 2021 00:00:00 +0000

Complete streets are those designed not only for private vehicles, but also to enable safe access for all users, including pedestrians, bicyclists, motorists, and transit riders of all ages and abilities. Specific street designs vary based on the type of street. Complete streets are intended to improve non-motorized travel safety, reduce costs and environmental burdens, and create more livable, sustainable, and economically vibrant communities. Investment in complete streets projects is growing around the country with these goals in mind. However, there are limited data to verify the effectiveness of complete streets, and the indicators required for quantification of complete street performance are not yet agreed upon. Complete street sustainability indicators are important to assess whether a complete street conversion is achieving its goals and to support decision-making for complete street investment.
Researchers at the University of California, Davis and JCH Research...

A Method of Identifying Critical Road Infrastructure for Maintaining Food Accessibility

Thu, 11 Mar 2021 00:00:00 +0000

A key purpose of the transportation system is to provide access to critical services such as grocery stores. Maintaining food access during an emergency or other disruption is all the more important, particularly for vulnerable households. Most people in the United States rely on the use of private automobiles for grocery shopping. Thus, disruptions to road networks due to heavy precipitation, flooding, or even major maintenance and repair projects present notable threats to accessibility. Regional planning models that address food accessibility issues (not all do) typically do not consider households’ familiarity with grocery locations. However, during a disruptive event, a household’s familiarity with at least one available route to a retail grocery location becomes paramount. Identifying the roadways that are most critical to food access can help decision makers devise strategies to mitigate the risks of food insecurity for vulnerable households and populations.
Researchers...

Stakeholder Perspectives on the Sustainable Transportation Implications of On-demand Ridehailing

Thu, 4 Mar 2021 00:00:00 +0000

There is much uncertainty over whether on-demand ridehailing services, namely Uber and Lyft, will worsen or alleviate existing transportation problems such as congestion, emissions, and inequities in access and mobility. For policymakers, transportation planners, and others in the transportation arena, these unknowns have created uncertainty over which policies would best steer ridehailing toward equitable and sustainable outcomes. To address these uncertainties, researchers at UC Davis assessed how stakeholders from different groups view the possible impacts of ridehailing and the policies that might best address those impacts. The researchers evaluated these questions through in-depth interviews with stakeholders from 38 agencies and organizations throughout California. Interviewees included transportation planners, members of state agencies, and representatives from non-profit organizations and the ridehailing industry. This policy brief summarizes those interviews, as...

User Perceptions of the Risks of Electric, Shared, and Automated Vehicles Remain Largely Unexplored

Fri, 12 Feb 2021 00:00:00 +0000

Advocates of electric, shared, and automated vehicles (e-SAVs) envision a future in which people no longer need to drive their privately owned, petroleum-fueled vehicles. Instead, for daily travel they rely on fleets of electric, automated vehicles that offer travel services, including the option to share, or “pool,” rides with strangers. The design, deployment, and operation of e-SAVs will require widespread willingness of users to share with strangers vehicles that are capable of fully automated driving. To achieve the environmental and societal goals of e-SAVs it is critical to first understand and address safety and security concerns of potential and actual users. Researchers at the University of California, Davis, reviewed the literature to understand potential users’ perceptions of safety and security risks posed by intertwined social and technical systems of e-SAVs and proposed a framework to advance research, policy, and system design. This policy brief summarizes the...

Alkali-Activated Materials are Promising Alternatives for Reducing Roadway Emissions

Tue, 26 Jan 2021 00:00:00 +0000

Planned substantial road infrastructure investments emphasize the need for alternative materials that can reduce economic and environmental costs. Alkali-activated materials are one such alternative. These inorganic binders can be produced with fewer CO₂ emissions than asphalt and concrete binders while offering comparable mechanical properties. Alkali-activated materials also develop strength more rapidly, facilitating rapid construction and large-scale repair and maintenance operations.
Existing studies suggest that alkali-activated materials would produce fewer CO₂ emissions than conventional cement. However, work to date has not considered availability of the precursors needed to produce alkali-activated materials. Limited availability of raw materials could result in significant additional emissions from transporting materials long distances to market. Researchers at the Georgia Institute of Technology analyzed published life cycle assessment literature to understand...

Environmental Reviews Fail to Accurately Analyze Induced Vehicle Travel from Highway Expansion Projects

Sun, 24 Jan 2021 00:00:00 +0000
Induced travel is a well-documented effect in which expanding highway capacity increases the average travel speed on the highway, which in turn reduces the perceived “cost” of driving and thereby induces more driving. This increase in vehicle miles traveled (VMT) increases congestion (often back to pre-expansion levels) and air pollutant emissions, reducing or eliminating the purported benefits of the expansion. Yet highway expansion projects continue to be proposed across California, often using congestion relief—and sometimes greenhouse gas reductions—as a justification for adding lanes. These rosy projections about the benefits of highway expansion projects indicate that the induced travel effect is often not fully accounted for in travel demand models or in the projects’ environmental review process. With this problem in mind, researchers at the University of California, Davis developed an online tool to help agencies estimate the VMT induced annually by adding lanes to major...

Road User Charge Administration: Lessons Learned from Fuel Taxes

Wed, 20 Jan 2021 00:00:00 +0000

State and federal governments rely on fuel taxes to help build and maintain roads, bridges, and other transportation infrastructure. The federal gasoline tax has not been increased since 1993 and inflation, improvements in fuel efficiency, and an increasing share of electric vehicles on the road have created a revenue shortfall from fuel taxes in the Highway Trust Fund.
Many states have begun conducting pilot programs for a road user charge, or mileage-based user fee, which would impose a fee per mile for drivers rather than a charge per gallon of fuel. Benefits of this system are that it is not sensitive to changes in drivetrain technology to electric vehicles, can be designed to be less regressive than a gasoline tax, and can be easily adjusted for inflation. However, implementing a new tax would have challenges. This policy brief summarizes findings and policy implications from University of California, Davis research that assessed the administration of the gasoline...

A Road Map for Advancing Permeable Pavement as a Stormwater, Transportation, and Flood Control Solution

Fri, 13 Nov 2020 00:00:00 +0000

The University of California Pavement Research Center and the Interlocking Concrete Pavement Institute worked with partners in the concrete and asphalt pavement industries and Tongji University to organize a workshop in November 2017 with the goals of identifying knowledge, information, and communication barriers to adoption of permeable pavement of all types, and then creating a road map to address and overcome them. The workshop brought together stakeholders from the planning, stormwater quality, flood control, and pavement communities to listen to presentations, exchange ideas, discuss unanswered questions identified by the group, and develop a proposed road map to fill the gaps in knowledge, processes, and guidance. Participants represented local, state and federal government, consultants, non-governmental organizations, contractors/ material producers, and academia. The road map produced from the discussions is built around “routes” of proposed actions to remove technical...

The Impacts of Automated Vehicles on Center City Parking Demand, Congestion, and Emissions

Wed, 7 Oct 2020 00:00:00 +0000

Parking has long been an urban planning challenge. Providing parking in city centers is land-intensive and expensive. Moreover, drivers searching for scarce parking can increase congestion, vehicle miles traveled (VMT), and greenhouse gas (GHG) emissions. Use of automated vehicles to drop off and pick up travelers could reduce the demand for parking, which could reduce VMT and associated emissions and allow urban spaces currently used for parking to be converted to more beneficial uses. However, automated vehicles could also have negative consequences. They could generate empty vehicle travel and more cross-traffic movements due to drop-offs and pick-ups which could increase congestion, VMT, and GHG emissions.
Researchers at the University of California, Davis modeled the travel effects of changes in drop-off and pick-up activity and parking supply that might be triggered by widespread automated vehicle use in San Francisco’s city center. A primary goal of this research...

An Adaptive Strategy for Connected Eco-Driving under Uncertain Traffic and Signal Conditions

Fri, 25 Sep 2020 00:00:00 +0000

Connected and automated vehicle technology could bring about transformative reductions in traffic congestion, greenhouse gas emissions, air pollution, and energy consumption. Connected and automated vehicles (CAVs) can directly communicate with other vehicles and road infrastructure and use sensing technology and artificial intelligence to respond to traffic conditions and optimize fuel consumption. An eco-approach and departure application for connected and automated vehicles has been widely studied as a means of calculating the most energy-efficient speed profile and guiding a vehicle through signalized intersections without unnecessary stops and starts. Simulations using this application on roads with fixed-timing traffic signals have produced 12% reductions in fuel consumption and greenhouse gas emissions. But real-world traffic conditions are much more complex—uncertainties and the limited sensing range of automated vehicles create challenges for determining the most energy-efficient...

Increasing Highway Capacity Unlikely to Relieve Traffic Congestion

Fri, 18 Sep 2020 00:00:00 +0000

Reducing traffic congestion is often proposed as a solution for improving fuel efficiency and reducing greenhouse gas (GHG) emissions. Traffic congestion has traditionally been addressed by adding additional roadway capacity via constructing entirely new roadways, adding additional lanes to existing roadways, or upgrading existing highways to controlled-access freeways. Numerous studies have examined the effectiveness of this approach and consistently show that adding capacity to roadways fails to alleviate congestion for long because it actually increases vehicle miles traveled (VMT).
An increase in VMT attributable to increases in roadway capacity where congestion is present is called “induced travel”. The basic economic principles of supply and demand explain this phenomenon: adding capacity decreases travel time, in effect lowering the “price” of driving; and when prices go down, the quantity of driving goes up. Induced travel counteracts the effectiveness of capacity...

Efficient Empty Container Movement Considering the Next Day’s Demand Can Reduce Port Congestion

Mon, 14 Sep 2020 00:00:00 +0000

International trade continues to grow, increasing container traffic at seaports worldwide. The Port of Los Angeles saw a 20% increase in throughput from 2010-2018. Typically, loaded containers arriving at the ports are transported by truck to inland importers, emptied, and then returned to the port. The empty containers are then driven to inland exporters to be loaded and returned to the port for shipping. This lack of direct container exchange between importers and exporters, known as the empty container reuse problem, adds many truck trips to Southern California highways and adds significant expenses for shipping companies. Trucks transporting empty containers contribute to traffic congestion, greenhouse gas emissions, and local air pollution.
Moving empty containers more efficiently could significantly reduce truck trips and the associated congestion and pollution. Researchers at the University of Southern California developed an optimization-based vehicle scheduling...

Cost, Congestion, and Emissions Benefits of Centralized Freight Routing and Efficiencies in Alternative Fuel Freight Modes

Thu, 27 Aug 2020 00:00:00 +0000

International trade continues to increase, with container trade growing at a 9.5% annual rate worldwide and at a 6% annual rate in the United States. Container ships are also getting bigger to meet this growing demand. As a result, cargo is concentrated into the largest ports, which intensifies bottlenecks on the road networks surrounding these ports. Thus, logistics companies are faced with increasing complexity in their operations and increasing traffic congestion that adds costs, as well as greenhouse gas emissions and local air pollution. The transition to zero emission truck technology could add further complexity, requiring companies to plan for electric trucks’ shorter ranges and longer refueling times.
Researchers at the University of Southern California developed a centrally coordinated freight routing system and ran several simulations to minimize the social costs of freight transportation, also accounting for adoption of electric trucks. The researchers also...

Climate Action Plans Should Quantify Life Cycle Greenhouse Gas Emissions and Costs to Achieve Meaningful, Cost-Effective Emissions Reductions

Fri, 14 Aug 2020 00:00:00 +0000

Local governments increasingly prepare Climate Action Plans to lay out specific strategies for achieving local and state greenhouse gas reduction goals. Strategies to reduce transportation emissions are often a key component of these plans, as the transportation sector is responsible for 41% of greenhouse gas emissions in California and 28% in the US. However, many Climate Action Plans do not quantify the emissions reductions or costs of proposed strategies, and even fewer consider the life cycle impacts of the strategies. Life cycle-based assessments consider emissions and costs that occur at the outset of a strategy’s implementation (e.g., purchase, installation, and construction), during operation and maintenance, and at end-of-life. Quantifying the life cycle cost effectiveness and emissions reductions of different strategies can, along with other community priorities, inform the design and implementation of Climate Action Plans that achieve climate goals at a reasonable...

City Planner Survey Reveals the Most Common Tools for Promoting Transit-Oriented Development

Fri, 14 Aug 2020 00:00:00 +0000

Transit-oriented development—higher density residential or mixed-use development centered around high-quality transit stations—can reduce the need for driving and cut vehicle greenhouse gas emissions. It can also play a role in revitalizing downtowns, improving accessibility for residents, and preserving open space. For these reasons, state and local governments in California have adopted goals and policies to support transit-oriented development.
Despite its benefits, transit-oriented development faces multiple barriers. Projects may face more complex planning, financing, and regulatory hurdles, and often entail higher land and development costs compared to greenfield development. Local governments are confronting these challenges through the adoption of innovative policy, planning, and finance tools. Researchers at the University of California, Davis surveyed almost 150 city planning directors in California’s four largest metropolitan areas to better understand cities’...

Future Electric Vehicle Charging Demand at Highway Rest Areas and Implications for Renewable Energy Penetration in California

Fri, 24 Jul 2020 00:00:00 +0000

California has goals to rapidly expand electric vehicle adoption, with executive orders calling for 1.5 million electric vehicles on the roads by 2025 and 5 million by 2030. Significant charging infrastructure will be needed to support these new vehicles. While many urban areas in California have prioritized construction of charging stations, most rural areas lack charging infrastructure. This deficit hinders electric vehicle adoption in rural areas and makes long distance electric vehicle travel difficult.
To address this issue, Caltrans has begun investing in charging infrastructure in rural and underserved areas around the state, particularly at highway rest areas. However, an understanding of potential future intercity charging demand will be needed to inform continued investments in support of a growing electric vehicle fleet.
This policy brief summarizes findings from researchers at the University of California, Davis, who collected state travel data and electricity...

Using Genetic Tools to Identify Populations Within Species Could Ease Infrastructure Mitigation

Wed, 15 Jul 2020 00:00:00 +0000

Recent research suggests that bird populations are declining at alarming rates across the United States. Over the last century, local, national, and international efforts to limit declines in bird populations have resulted in state and federal laws that now protect most of California’s 650 bird species. To comply with these protections, transportation infrastructure projects often face strict mitigation requirements, which can be expensive and cause delays. Understanding a project’s effects on specific bird populations can refine mitigation requirements and optimize infrastructure planning.
The tools for identifying separate populations within species and understanding protected birds’ seasonal movement have been limited until recently. New genetic and genomic tools now provide a method for understanding population differentiation, which is vital to a wide array of conservation goals including estimating population declines, identifying potential for adaptation to stressors,...

Recent itsdavis_ncst_policy items

Benchmarking Global Road Transportation Greenhouse Gas Emissions from 2021–2050

County Sales Tax Measures for Transportation Can Affect Regional Plans for Sustainable Transportation

BikewaySim Expected to Improve Bicycle Infrastructure Planning Process

The Safe Systems Pyramid

Mitigating CO2 Emissions from California’s Concrete Infrastructure

High Percentages of Reclaimed Asphalt Affect the Performance of Asphalt Binder

Last-Mile Delivery Innovations and Best Practices in the Age of E-commerce

Challenges Are Present, But California Transit Agencies Are Open to Open-loop

Trip-Level Mode Replacements and Daily Activity Patterns Reveal the Sustainability Potential of Micromobility

Travel and the Built Environment in Rural Communities

Who Experiences Rural Travel Burdens? Evidence from Car-Limited and Latin American Migrant Households

Bikesharing and other micromobility services can improve connectivity between affordable housing communities and transit

Sustainable Incentives for Accelerating the Zero Emission Vehicle Transition

Extending public transit through micromobility facilities and services in the Bay Area

Jobs and Automation in the Freight and Warehousing Sector

Using Vehicle Miles Traveled Instead of Level of Service as a Metric of Environmental Impact for Land Development Projects: Progress in California

Mileage Fees: An Equitable and Financially Viable Alternative to the Gas Tax

Impacts of the Federal Tax Credit on the Decision to Lease or Purchase a Plug-in Electric Vehicle

Benefits of Battery Electric Heavy-Duty Trucks Increase Rapidly over Time

Household Vehicle Choice in California: Behavior and Impacts

California Cities Face Trade-offs in Developing Plans and Policies for Transit-Oriented Development

Best Practices for Science Communication: Messaging and Reputation

E-bike Incentive Programs Reduce GHGs and Support Recreational Travel

New Tool for Gig Drivers Considering Going Electric

Do Slow Streets Encourage More Dockless Travel? Evidence from Electric Scooter Usage in Four Cities

Land Use Efficiency Tool Improvements May Help Governments Meet Sustainability Targets Equitably

US-Mexico Second-hand Vehicle Trade: Implications for responsible EV end of life management and material circularity in North America

Community-Oriented Solutions May Help Rural Residents Adapt to Life Without a Car

Flexible Routing for Ridesharing

Updating the Induced Travel Calculator

Increasing Highway Capacity Induces More Auto Travel

Travel Behavior Trends During the COVID-19 Pandemic

How Intelligent Vehicle Technologies Can Improve Vulnerable Road User Safety at Signalized Intersections

Demonstrating the Life Cycle Assessment Framework for Complete Streets

Planning Can Maximize Benefits and Mitigate Negative Consequences of Future Travel Increases from E-Commerce

Incentive Systems for New Mobility Services to Reduce Congestion

Understanding the Bike-share Market in the Sacramento Region to Increase Demand and Improve Access

Advancing Seaport Environmental Sustainability: Case Studies from the San Pedro Bay Ports Clean Air Action Plan

The Impact of Ridehailing on Other Travel Modes and on Vehicle Dependency

The Costs of Owning Battery-Electric Trucks – Is the Research Aligning?

Evaluating Pilot Approaches to Increase Rural Mobility

Real-World Brake Activity Testing in Heavy-Duty Vehicles to Inform Emissions Inventories

Variable Speed Limit Control to Reduce Traffic Congestion in the Face of Uncertainty

Grid Energy Storage Assessment for Select Vehicle Electrification Scenarios

A Glimpse of Microtransit at an Early Stage: The SmaRT Ride Consumer Market in the Sacramento Area

The Requirements, Costs, and Benefits of Providing Charging Infrastructure for Heavy-Duty Electric Trucks at California’s Rest Areas

What to Make of Biofuels? Understanding the Market from 2010 to the Present, and Projecting Ahead to 2030 Given Current Policies

Future Connected and Automated Vehicle Adoption Will Likely Increase Car Dependence and Reduce Transit Use without Policy Intervention

A Model for Efficiently Allocating Resources to Mitigate Wildfire Risk along California Roadways

Do Dock-based and Dockless Bikesharing Systems Provide Equitable Access for Disadvantaged Communities?

A Truck Routing Model to Reduce Fuel Consumption and Emissions while Accounting for Parking Availability and Working Hours Constraints

Single-Family Neighborhoods in Sacramento Have Sufficient Parking to Accommodate Accessory Dwelling Units

What Will a Transition to Digital Transit Payments Mean for Un- and Underbanked Transit Passengers?

How Much Do Local Climate Action Plans in California Consider Emissions, Cost, and Equity?

Simulating the Effects of Shared Automated Vehicles and Benefits to Low-Income Communities in Los Angeles

BikewaySim and Complete Paths Networks are Expected to Improve Modeling of Bicycle Activity and Route Choice

Publicly Funded Electric Carsharing Services Can Reduce Emissions and Expand Transportation Access, but They Need More Study

A Roadmap for Integrating Complete Streets Infrastructure into Pavement Asset Management Systems

Urban Design that Reduces Vehicle Miles Traveled Can Create Economic Benefits

Expanding the UC Davis GIS Electric Vehicle Planning Toolbox Beyond California

Do Travel Surveys Show that Californians Walked and Biked Less in 2017 than in 2012?

Material Efficiency as a Means to Lower Environmental Impacts from Concrete

Quantifying Environmental Impacts from Concrete Production, While Accounting for Data Variability and Uncertainty

Autonomous Vehicle Policies Must Be Flexible to Support Deployment in Rural Regions

Where Are Buyers of Used Electric Vehicles in California?

Dynamic Routing to Improve the Efficiency of Ride-Sharing

Expanded Workforce Development Opportunities are Needed for Transportation Sector Climate Adaptation Professionals

Failing Shopping Malls Can Be a Powerful Tool for Addressing California’s Affordable Housing Shortage

Costs, Reliability, Vehicle Characteristics, and Incentives are the Top Factors Influencing Freight Vehicle Technology Choices

Curbside Management Is Critical for Minimizing Emissions and Congestion

Exposure to Electric Vehicle Technology at Home and Work Can Fuel Market Growth

Setting Transportation Network Company Policies to Increase Sustainability

Across Early Policy and Market Contexts, Women and Men Show Similar Interest in Electric Vehicles

Telecommuting Rates During the Pandemic Differ by Job Type, Income, and Gender

Congestion Reduction via Personalized Incentives

Cost of Vehicle Ownership: Cost Parity Between Plug-in Electric Vehicles and Conventional Vehicles Is at Least a Decade Away

Millennial Travelers Are More Multimodal than Older Travelers, but This Trend Might Change as They Age

Ridehailing Demand Is Resilient Among Low-Income Travelers During the COVID-19 Pandemic

Instantaneous Hybridization Factor: New Metric to More Accurately Model Hybrid-Electric Vehicle Emissions

Mitigating CO₂Emissions from California’s Concrete Infrastructure