research report

Benefits, Challenges, and Opportunities of Different Last-Mile Delivery Strategies

Abstract

As online shopping nears its third decade, it is clear that its impacts on urban goods flow are profound. Increased freight traffic and related negative externalities such as greenhouse gas emissions and local air pollution can impede sustainability goals. In response, e-retailers are exploring innovative distribution strategies to enhance last-mile delivery sustainability and efficiency. They use urban consolidation centers with light-duty vehicles like electric vans and cargo bikes, establish alternative customer pickup points, and deploy crowdsourced delivery networks. Advanced technologies that may streamline deliveries, such as autonomous delivery robots and unmanned aerial vehicles, are being tested. University of California Davis and Irvine researchers have investigated these strategies under economic viability, environmental efficiency, and social equity frameworks. Different modeling approaches were implemented to evaluate last-mile network designs and the potential for decarbonizing delivery fleets by switching to electric vehicles. Key findings suggest that while these innovative strategies offer substantial environmental benefits and reduce operational costs, they also present challenges like higher initial investments and operational hurdles. The study emphasizes the need for ongoing innovation and careful strategy implementation to balance sustainability with urban delivery systems’ economic and service reliability demands.

published journal article

Real-World Activity Patterns of Heavy-Duty Battery Electric Trucks from Regional Distribution Fleets in Southern California

Abstract

Heavy-duty trucks are a major source of transportation-related greenhouse gas and criteria pollutant emissions. One approach to reducing these trucks’ climate and health impacts is to transition them to zero-emission technologies such as battery electric trucks (BETs). To date, BETs have been deployed mostly in drayage applications. As the performance of BETs has improved in recent years, there is increasing interest in using BETs also in regional haul applications. This paper examines real-world activity patterns of 15 heavy-duty BETs in regional haul applications using data collected from early deployments of these trucks across eight different fleets in Southern California. The results show that the BETs are typically utilized on routes (or tours) that are much shorter than their driving ranges. They often make one or two tours per day and are usually charged at the end of each tour. Due to the variation in the time of day that the BETs are operated, they are charged at different times of day, spreading the charging load throughout the day. In addition, the results indicate that about half of the BET’s operations on average occur in or around disadvantaged communities, providing emission reduction benefits to these communities.

published journal article

Quantifying the Employment Accessibility Benefits of Shared Automated Vehicle Mobility Services: Consumer Welfare Approach Using Logsums

Abstract

The goal of this study is to assess and quantify the potential employment accessibility benefits of shared-use automated vehicle (AV) mobility service (SAMS) modes across a large diverse metropolitan region considering heterogeneity in the working population. To meet this goal, this study proposes employing a welfare-based (i.e. logsum-based) measure of accessibility, obtained via estimating a hierarchical work destination-commute mode choice model. The employment accessibility logsum measure incorporates the spatial distribution of worker residences and employment opportunities, the attributes of the available commute modes, and the characteristics of individual workers. The study further captures heterogeneity of workers using a latent class analysis (LCA) approach to account for different worker clusters valuing different types of employment opportunities differently, in which the socio-demographic characteristics of workers are the LCA model inputs. The accessibility analysis results in Southern California indicate: (i) the accessibility benefit differences across latent classes are modest but young workers and low-income workers do see higher benefits than high- and middle-income workers; (ii) there are substantial spatial differences in accessibility benefits with workers living in lower density areas benefiting more than workers living in high-density areas; (iii) nearly all the accessibility benefits come from the SAMS-only mode as opposed to the SAMS+Transit mode; and (iv) the SAMS cost per mile assumption significantly impacts the magnitude of the overall employment accessibility benefits.

research report

Evaluating the Seismic Vulnerability and Resilience of BART’s Berkeley Hills Tunnel

Publication Date

January 1, 2025

Author(s)

Esra Zengin, Yousef Bozorgnia, Jonathan P. Stewart

Abstract

Critical nodes in transportation networks, such as major transit tunnels and interchange stations, are vital for maintaining system functionality following a disruptive event such as a large earthquake. This project focuses on evaluating the seismic resilience of BART’s Berkeley Hills Tunnel that intersects the Hayward Fault, one of California’s most active seismic zones. The Hayward Fault poses a significant risk, with the potential for a magnitude 7+ earthquake that could severely impact the tunnel, potentially disrupting BART service and affecting the broader transit network. This study employs the latest fault displacement hazard data and models to estimate the probability of fault rupture displacements and assesses the resulting damage. It then evaluates the likelihood of service interruptions caused by potential Hayward Fault events. Theresults suggest that the tunnels may experience minor to significant damage depending on the amplitude of the faultdisplacement, which can lead to repair times ranging from a few weeks to over a year. The findings highlight the importance of improving tunnel resilience to minimize service disruptions and ensure efficient recovery following major earthquakes.

policy brief

A Detailed Look at How the Pandemic Changed Travel Patterns Across Regions in Northern California Megaregion

Abstract

Many studies have focused on the shifts in travel patterns caused by the COVID-19 pandemic and how travel demand continues to evolve in the post-pandemic era. Key metrics such as trip volume–the total number of trips within a specific area–help explain the pandemic’s impact on travel demand over time. However, to fully understand changes in travel behaviors, it is also important to analyze where trips start and end—otherwise known as Origin-Destination (OD) demand.
To better understand OD demand during and after the pandemic, the research team developed a data-driven methodology to analyze travel patterns across different regions, times of day, days of the week (weekday and weekend), and trip purpose. This study used passively collected location-based data from the StreetLight Data platform (StreetLight Data, 2022) in the form of weekly OD matrices of all vehicle modes, segmented by various relevant variables. It focused on the Northern California Megaregion, which includes 21 counties from the San Francisco Bay Area to the Sacramento region and the northern part of the San Joaquin Central Valley. The study period spanned from January 2019 to October 2021.

policy brief

The Costs and Gains of Raising Truck Speed Limits

Abstract

Highway speed limits are increasing across the United States (Figure 1). There is also a national trend toward uniform speed limits, within states, for both passenger vehicles and trucks. California is one of only seven remaining states that sets different speed limits, with lower speed limits for trucks than passenger vehicles. While higher speed limits provide operational benefits by shortening travel times and fostering economic benefits—especially for the trucking and logistics industries—they can also increase the likelihood and severity of crashes since higher vehicle speeds require longer stopping distances and generate more energy during a collision.
While there is no consensus on the optimal speed limit, research generally shows that lower speed limits reduce the frequency and severity of crashes. Likewise, there is mixed evidence on whether universal (i.e., same for trucks and passenger vehicles) or differential speed limits are safer. While some evidence suggests that setting lower speed limits for heavier trucks that take longer to stop has safety benefits, others argue that differential speed limits create bottlenecks may cause more crashes as cars attempt to overtake slower-moving trucks.
The research team used traffic simulation and statistical models to estimate the costs of crashes, travel time, and vehicle operation for various speed limit scenarios in California. Analysis focused on the economic and comprehensive costs associated with fatal and severe traffic crashes, as outlined by the National Safety Council. They derived key metrics such as traffic speeds, travel times, and distances by simulating typical highway operating conditions. These insights helped calculate the overall economic and operational impact across the state’s highway system.

policy brief

What are the Public Health and Environmental Implications of Drayage Truck Electrification Targets in California?

Abstract

To better understand the implications of transitioning drayage trucks to zero-emission, this project analyzed the health impacts and GHG freeway emissions from diesel-powered drayage trucks and the benefits of replacing them with zero-emission trucks, accounting for current and expected air quality regulations. The study area stretched between the San Pedro Bay and the Inland Empire, home to large warehouse complexes. It focused on two years: 2012 (when pre-2007 drayage trucks were phased out in the Clean Air Action Plan), and 2035 (the deadline in Executive Order N-79-20). The analyses incorporated projections of the size and composition of the vehicle fleets from data collected by the California Air Resources Board (CARB), estimates of future emission factors from the U.S. Environmental Protection Agency that account for projected technology improvements, and projected increases in cargo demand at the ports in 2035 compared to 2012.

preprint journal article

A Choice Experiment Survey of Drayage Fleet Operator Preferences for Zero-Emission Trucks

Abstract

Many U.S. states are supporting the transition of the heavy-duty vehicle (HDV) sector to zero-emission vehicles (ZEVs), with California leading the way through its policy and regulatory initiatives. Within various HDV fleet segments, California’s drayage fleets face stringent targets, requiring all vehicles newly registered in the Truck Regulation Upload, Compliance, and Reporting System to be ZEVs starting January 2024, and all drayage trucks in operation to be zero-emission by 2035. Understanding fleet operator behavior and perspectives is crucial for achieving these goals; however, it remains a critical knowledge gap. This study investigates the preferences and influencing factors for ZEVs among drayage fleet operators in California. A stated preference choice experiment survey was conducted, developed based on previous qualitative studies and literature reviews. With participation from 71 fleets of various sizes and alternative fuel adoption status, there were 648 choice observations in a dual response design collected, consisting of a forced choice between ZEVs and a free choice between ZEVs and status quo alternatives. Multinomial logit model analyses revealed driving range and purchase costs as significant factors for ZEV adoption, with charging facility construction costs also critical in hypothetical choices between ZEVs and status quo alternatives. Fleet or organization size also influenced ZEV choices, with large fleets more sensitive to operating costs and small organizations more sensitive to off-site stations. These findings enhance understanding in this area and provide valuable insights for policymakers dedicated to facilitating the transition of the HDV sector to zero-emission.

preprint journal article

Charging Infrastructure Decisions by Heavy-duty Vehicle Fleet Operators: An Exploratory Analysis

Abstract

Insufficient charging/fueling infrastructure poses a major challenge to achieving U.S. policy goals for transitioning the heavy-duty vehicle (HDV) sector to zero-emission vehicles. Addressing the infrastructure needs of HDV fleet operators, who are key demand-side stakeholders, is crucial for developing effective solutions and strategies. This study investigates these needs through a fleet survey of California’s drayage sector, focusing on battery electric trucks. Key aspects examined include preferences for charging locations, access types, charging duration, time-of-day for charging, and innovative solutions like Truck-as-a-Service. Analyzing responses from 53 companies with varying fleet sizes, annual revenues, and operational characteristics, the study employed a comprehensive exploratory approach, utilizing descriptive analysis, thematic analysis, and hypothesis testing. Findings reveal that while most fleets preferred on-site charging, about a quarter, primarily smaller fleets with five or fewer trucks, preferred both on-site and off-site options. Private access was often favored for on-site facilities, though some respondents recognized the benefits of shared access for expanding operational coverage. The study also identified a need for faster charging solutions at both off-site and on-site locations, particularly for long-haul or mixed operations. Time-of-day preferences varied widely, driven by the need for efficient operations. Furthermore, a small proportion of participating fleets preferred Truck-as-a-Service over traditional procurement, predominantly among smaller fleets or those with lower revenues. The comprehensive research findings contribute to a deeper understanding of charging infrastructure needs and offer practical insights for policy practitioners and industry stakeholders committed to advancing zero-emission infrastructure. ​​

preprint journal article

Small and Large Fleet Perceptions on Zero-emission Trucks and Policies

Abstract

Given that small fleets (defined as those with 20 or fewer vehicles) represent a considerable portion of the heavy-duty vehicle (HDV) sector, understanding their perspectives, along with those of large fleets, on zero-emission vehicles (ZEVs) and related policies is crucial for achieving the U.S. HDV sector’s ZEV transition goals. However, research focusing on small fleets or comparing both segments has been limited. Focusing on California’s drayage sector with stringent ZEV transition targets, this study investigates the awareness and perceptions of small and large fleet operators on ZEV technologies and policies established to promote ZEV adoption. Using a fleet survey, we obtained 71 responses from both small and large fleets. We employed a comprehensive exploratory approach, utilizing descriptive analysis, hypothesis testing, and thematic analysis. Findings reveal that both segments generally rated their ZEV knowledge as close to neutral, with about a third reporting limited awareness of the ZEV policy. Both segments highlighted various adoption barriers, including challenges with infrastructure, costs, and operational compatibility. Business strategies under the ZEV policy differed significantly: small fleets planned to delay or avoid ZEV procurement, with some considering relocation, while large fleets were more proactive, with many already having procured or preparing to procure ZEVs. Both segments voiced concerns about the disproportionate impact on small fleets. The findings enhance our understanding of equity issues in ZEV adoption across fleet segments and offer valuable insights for policymakers committed to a more equitable distribution of the impacts. ​​