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Open Access Publications from the University of California
Cover page of The Costs of Owning Battery-Electric Trucks – Is the Research Aligning?

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

(2022)

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 University of California, Davis reviewed 10 recent studies of the total cost of ownership of battery-electric trucks, now and in the future, compared to a baseline diesel truck. The researchers did not judge these studies against each other but attempted to derive general findings that are robust across all the studies. This policy brief summarizes the key findings from that research.

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

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

(2022)

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

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

(2022)

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 when needed to the upstream vehicles, as well as ramp control to manage incoming traffic, while accounting for inaccuracies in traffic data and road information and the complex behavior of human driving. This policy brief summarizes the key findings from that research.

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Cover page of Evaluating Pilot Approaches to Increase Rural Mobility

Evaluating Pilot Approaches to Increase Rural Mobility

(2022)

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.

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

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

(2022)

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 and informing efforts to improve non-tailpipe PM emissions inventories. This policy brief summarizes the key findings from that research.

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

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

(2022)

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 that would safeguard against unintended consequences such as additional emissions from land use changes or higher food prices that can come from competition with the use of crops for fuel. This policy brief summarizes the findings from that research and provides policy implications.

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

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

(2022)

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. This policy brief summarizes the findings from that research and provides policy implications.

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

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

(2022)

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 the vehicle miles traveled and emissions of each scenario using a statewide travel demand model, emissions factors from California agencies, and assumptions derived from the scientific literature and expert input. This policy brief summarizes the findings from that research and provides policy implications.

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

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

(2022)

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 prioritization model for vegetation management within highway rights-of-way. The researchers also interviewed Caltrans staff about opportunities for and obstacles to increasing the pace and scale of vegetation treatments. This policy brief summarizes the findings from that research and provides policy implications.

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

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

(2022)

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 accommodate the vehicles associated with the residents of both a primary dwelling and a potential ADU. This policy brief summarizes the findings from that research and provides policy implications.

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