research report

Employing a Modified Delphi Approach to Explore Scenarios for California’s Transportation and Land Use Future

Abstract

There are many methods for engaging experts in interactive groups to explore, clarify, and/or decide on various issues. In an investigation of possible future transportation and land use scenarios for California, the research paper used techniques common to several methods and developed our own variation, a “hybrid policy Delphi,” for use with a panel of 18 experts. The research team applied it to explore the policies that would lead to these scenarios and the consequences that would result from them. Through our process, panel members discussed and reported on the future scenarios they considered most desirable and also the scenarios they considered most likely to materialize by 2050. Panelists reported that the scenario they considered the most desirable was also least likely to occur and that the likely trajectory of California transportation and land use policies and practices will lead to the scenario panelists considered less desirable. This report reflects on the processes behind reaching these panel conclusions, a five-stage sequence of two meetings and three online questionnaires. Our mix of discussion and questionnaires traded the benefit of anonymity (common in Delphi methods) for the benefit of exploratory discussion (used in workshops, focus groups, and the nominal group technique). In addition, our use of surveys before and after meetings allowed tracking changes in panel opinion on a central question (scenario likelihood) and discussing survey results at meetings, at the cost of greater administrative effort. The paper discusses the results of this effort, reflects on how well our combination of methods worked and concludes with a discussion of limitations and future directions.

policy brief

How Well Are Newly Sited K-12 Schools Incorporating Vehicle Miles Traveled Mitigation Measures?

Abstract

In response to California law (SB 743, Chapter No. 386, Statutes of 2013), school districts are encouraged to use vehicle miles traveled (VMT) as criteria when evaluating the transportation impacts of new school construction, and identify feasible mitigation measures that eliminate or substantially reduce VMT generated by the new construction. To better understand the implications of this new law on school siting decisions, researchers at UC Berkeley analyzed 301 new schools constructed between 2008 and 2018 with respect to four VMT mitigation measures identified by the Governor’s Office of Planning and Research (OPR) known to minimize VMT – proximity to high quality transit areas (HQTA), proximity to roads with bicycle facilities, proximity to electric vehicle (EV) charging stations, and walkability scores.

published journal article

Longitudinal Analysis of COVID-19 Impacts on Mobility: An Early Snapshot of the Emerging Changes in Travel Behavior

Abstract

The COVID-19 pandemic has caused a huge disruption worldwide with direct and indirect effects on travel behavior. In response to extensive community spread and potential risk of infection, during the early stage of the pandemic, many state and local governments implemented non-pharmaceutical interventions that restricted non-essential travel for residents. This study evaluates the impacts of the pandemic on mobility by analyzing micro panel data (N = 1,274) collected in the United States via online surveys in two periods, before and during the early phase of the pandemic. The panel makes it possible to observe initial trends in travel behavior change, adoption of online shopping, active travel, and use of shared mobility services. This analysis intends to document a high-level overview of the initial impacts to spur future research to dive deeper into these topics. With the analysis of the panel data, substantial shifts are found from physical commutes to teleworking, more adoption of e-shopping and home delivery services, more frequent trips by walking and biking for leisure purposes, and changes in ride-hailing use with substantial variations across socioeconomic groups. The social and environmental implications of these findings are discussed and suggestions for effective policy and directions for future research are made in the conclusion.

research report

How Well Do New K-12 Public School Sites in California Incorporate Mitigation Measures Known to Reduce Vehicle Miles Traveled?

Abstract

California law (SB 743) requires school districts to measure the impact of school construction on the production of greenhouse gas emissions (GHG) and identify feasible mitigation measures that eliminate or substantially reduce the number of vehicle miles traveled (VMT) generated. This study analyzes 301 new schools constructed between 2008-2018 with respect to four VMT mitigation measures identified by the Governor’s Office of Planning and Research (OPR) known to minimize VMT (proximity to high-quality transit areas, proximity to roads with bicycle facilities, walkability scores, and proximity to electric vehicle charging stations). The analysis reveals mixed findings. Only about 16% of the new schools sited are located within ½ mile from high-quality transit. About 65% of new school sites are either connected or are close to (.06 miles or less) a bicycle network. Walkability scores varied greatly by location; approximately 60% of new school sites in “city” locales are considered walkable while sites in “rural” areas have low walkability scores. Nearly 60% (179) of new school sites are located within one mile of an EV charger, but only 19% are within one-quarter mile.

conference paper

Latent Class Analysis of Changes in the Use of Public Transportation in The Greater Los Angeles Region during the COVID-19 Pandemic

published journal article

Estimating the travel demand impacts of semi automated vehicles

Abstract

In this study, we investigate changes in travel due to level 2 automation among owners of electric vehicles in California. Level 2 automation has the potential to reduce driver fatigue and make driving less stressful which could mean drivers choose to travel more. We use questionnaire survey data to investigate changes to long-distance travel and annual vehicle miles traveled (VMT) due to automation. Results show those who report doing more long-distance travel because of automation are younger; have a lower household income; live in urban areas; own a longer-range electric vehicle; use automation in a variety of conditions; have pro-technology attitudes and prefer outdoor lifestyles. We use propensity score matching to investigate whether automation leads to an increase in annual VMT. The results of this show 4059–4971 more miles per year among users of level 2 automation compared to owners of similar vehicles without automation.

research report

Micromobility Trip Characteristics, Transit Connections, and COVID-19 Effects

Abstract

While micro-mobility services (e.g., bike-share, e-bike share, e-scooter share) hold great potential for providing clean travel, estimating the effects of those services on vehicle miles traveled and reducing greenhouse gases is challenging. To address some of the challenges, this study examined survey, micromobility, and transit data collected from 2017 to 2021 in approximately 20 U.S. cities. Micromobility fleet utilization ranged widely from 0.7 to 12 trips per vehicle per day, and the average trip distance was 0.8 to 3.6 miles. The median (range) rates at which micro-mobility trips substituted for other modes were 41% (16–71%) for car trips, 36% (5–48%) for walking, and 8% (2–35%) for transit, 5% (2–42%) for no trip. In most cities, the mean actual trip distance was approximately 1.5 to 2 times longer than the mean distance of a line connecting origin to destination. There was a weak and unclear connection between micro-mobility use and transit use that requires further study to more clearly delineate, but micro-mobility use had a stronger positive relationship to nearby rail use than to nearby bus use in cities with rail and bus service. The COVID-19 pandemic led to more moderate declines in docked than in dockless bike-share systems. Metrics that would enable a better assessment of the impacts of micro-mobility are vehicle miles traveled and emissions of micro-mobility fleets and their service vehicles, and miles and percentage of micro-mobility trips that connect to transit or substitute for car trips.

policy brief

New Metrics Are Needed to Understand the Environmental Benefits of Micromobility Services

Abstract

Micromobility services (e.g., conventional and electric bikeshare programs and electric scootershare programs) hold great potential for reducing vehicle miles traveled and greenhouse gas emissions if these services are used as substitutes for car travel and/or to access public transit. But estimating these environmental effects is challenging, as it requires measuring changes in human behavior—that is, the choice of what transportation mode to use. While many cities collect various micromobility usage metrics to regulate services, these metrics are not sufficient for calculating the sustainability benefits of these services.

published journal article

Direct measurements of ozone response to emissions perturbations in California

Abstract

A new technique was used to directly measure O3 response to changes in precursor NOx and volatile organic compound (VOC) concentrations in the atmosphere using three identical Teflon smog chambers equipped with UV lights. One chamber served as the baseline measurement for O3 formation, one chamber added NOx, and one chamber added surrogate VOCs (ethylene, m-xylene, n-hexane). Comparing the O3 formation between chambers over a 3-hour UV cycle provides a direct measurement of O3 sensitivity to precursor concentrations. Measurements made with this system at Sacramento, California, between April–December 2020 revealed that the atmospheric chemical regime followed a seasonal cycle. O3 formation was VOC-limited (NOx-rich) during the early spring, transitioned to NOx-limited during the summer due to increased concentrations of ambient VOCs with high O3 formation potential, and then returned to VOC-limited (NOx-rich) during the fall season as the concentrations of ambient VOCs decreased and NOx increased. This seasonal pattern of O3 sensitivity is consistent with the cycle of biogenic emissions in California. The direct chamber O3 sensitivity measurements matched semi-direct measurements of ratios from the TROPOspheric Monitoring Instrument (TROPOMI) aboard the Sentinel-5 Precursor (Sentinel-5P) satellite. Furthermore, the satellite observations showed that the same seasonal cycle in O3 sensitivity occurred over most of the entire state of California, with only the urban cores of the very large cities remaining VOC-limited across all seasons. The O3-nonattainment days (MDA8 O3>70 ppb) have O3 sensitivity in the NOx-limited regime, suggesting that a NOx emissions control strategy would be most effective at reducing these peak O3 concentrations. In contrast, a large portion of the days with MDA8 O3 concentrations below 55 ppb were in the VOC-limited regime, suggesting that an emissions control strategy focusing on NOx reduction would increase O3 concentrations. This challenging situation suggests that emissions control programs that focus on NOx reductions will immediately lower peak O3 concentrations but slightly increase intermediate O3 concentrations until NOx levels fall far enough to re-enter the NOx-limited regime. The spatial pattern of increasing and decreasing O3 concentrations in response to a NOx emissions control strategy should be carefully mapped in order to fully understand the public health implications.

research report

Travel Demand Modeling Methodology Recommendations for the Link21 Program

Abstract

This project aims to provide recommendations on the methodology and design specifications for the travel demand model to be built for the Link21 program in the Northern California megaregion. The Link21 program is a major rail investment program that will considerably improve and upgrade the passenger rail services in the Northern California megaregion, centered around the Transbay Corridor between Oakland and San Francisco in the San Francisco Bay Area. To support this effort, the research team reviewed the current and potential travel markets for the Link21 program, assessed the available travel demand models that could be used to support the modeling efforts for the Link21 program, and conducted interviews with experts from academic institutions, metropolitan planning organizations, state and federal agencies, and US DOE national labs. Considering the goals and objectives of the Link21 program, a list of 20 critical, important, and optional modeling features were identified, which should be considered for the Link21 program. The research team reviewed 11 existing travel demand models based on the evaluation of their modeling features and presented four proposed modeling approaches that could be considered to support the Link21 program. For each modeling approach, the research paper summarizes the pros and cons in terms of fulfilling the requirements of the Link21 program. The four modeling approaches include: 1) building on the Metropolitan Transportation Commission (MTC) TM 2.1 regional travel demand model without a dedicated long-distance travel model component; 2) building on the Metropolitan Transportation Commission TM 2.1 regional travel demand model with a dedicated long-distance travel model component; 3) building on the San Francisco County Transportation Authority (SFCTA) regional travel demand model with or without a dedicated long-distance travel model component; and 4) building on the California High-Speed Rail (CHSR) or the new statewide rail model that is currently under development. The study also discusses some sources of uncertainties that might affect future travel demand and the modeling practice in the Link21 regions. These include the impacts of the COVID-19 pandemic on work patterns and activity/travel choices, the introduction of shared mobility services, micro-mobility, the potential deployment of Mobility as a Service (MaaS) solutions, and the forthcoming deployment of connected and automated vehicles (CAVs). Given the complexity of the Link21 program and the requested 18-month timeline for developing a new travel demand model to support the program, the team recommends that the model development for the Link21 program be built on an existing modeling framework and adopt a modular system, which can be updated over time. An initial model release would become available in the proposed timeline of 18 months, while future updates and improvements in the model components could be added to future model updates. This process also would be well-suited to address eventual modeling issues that could arise with the initial model release, and it would benefit from the development and updates of other models in the Northern California megaregion that are being carried out in parallel.