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Open Access Publications from the University of California

The Institute of Transportation Studies at UC Berkeley has supported transportation research at the University of California since 1948. About 50 faculty members, 50 staff researchers and more than 100 graduate students take part in this multidisciplinary program, which receives roughly $40 million in research funding on average each year. Alexandre Bayen, Professor of Civil and Environmental Engineering and Professor of Electrical Engineering and Computer Science, is its director.

Cover page of How Might Adjustments to Public Transit Operations Affect COVID-19 Transmission?

How Might Adjustments to Public Transit Operations Affect COVID-19 Transmission?

(2022)

During the COVID-19 pandemic, public transportation systems worldwide faced many challenges, including significant loss of ridership. Public agencies implemented various COVID-19-related policies to reduce transmission, such as reducing service frequency and network coverage of public transportation. Recent studies have examined the effectiveness of these policies but reach different conclusions due to varying assumptions about how passengers may react to service changes.

Cover page of Automated Vehicle Technology Has the Potential to Smooth Traffic Flow and Reduce Greenhouse Gas Emissions

Automated Vehicle Technology Has the Potential to Smooth Traffic Flow and Reduce Greenhouse Gas Emissions

(2022)

In an ideal world, all cars along a congested roadway would travel at the same constant average speed; however, this is hardly the case. As soon as one driver brakes, trailing cars must also brake to compensate, leading to “stop and go” traffic waves. This unnecessary braking and accelerating increases fuel consumption (and greenhouse gas emissions) by as much as 67 percent.1 Fortunately, automated vehicles (AVs) — even Level 2 AVs2 which are commercially available today — have the potential to mitigate this problem. By accelerating less than a human would, an AV with flow smoothing technology is able to smooth out a traffic wave, eventually leading to free-flowing traffic (See Figure 1). To demonstrate the potential of flow smoothing on reducing greenhouse gas emissions, researchers at UC Berkeley used a calibrated model of the I-210 freeway in Los Angeles to simulate and measure the effect of deploying different percentages (10%, 20%, 30%) of flow-smoothing AVs on the average miles per gallon (MPG) of non-AVs in the traffic system.

Cover page of Where are Private “Smart City” Transportation Technologies Concentrated in California?

Where are Private “Smart City” Transportation Technologies Concentrated in California?

(2022)

In recent years, “smart city” information and communication technologies have proliferated. For local government agencies, procuring and introducing these technologies offers the possibility to manage infrastructure assets more effectively, plan for preventive maintenance, and disseminate schedules and information about transit and other services. Many of these technologies are deployed by private firms in the context of local regulations and government-sponsored incentives. In the transportation sector, examples of “smart city” technology services provided by private firms include: electric vehicle (EV) chargers, micro-mobility (e.g., scooter and bike rentals), and transportation network company (TNC) services, such as Uber and Lyft. To understand variation in how private sector smart city transportation technologies are deployed across California, researchers at UC Berkeley webscraped and cross verified data on EV chargers, Uber services, and micro-mobility. EV charger data was obtained from the Department of Energy, and Uber and micromobility access data came from vendor websites.

Cover page of Real-World Simulations of Life with an Autonomous Vehicle Suggest Increased Mobility and Vehicle Travel

Real-World Simulations of Life with an Autonomous Vehicle Suggest Increased Mobility and Vehicle Travel

(2021)

Fully autonomous vehicles are expected to have a profound effect on travel behavior. The technology will provide convenience and better mobility for many, allowing owners to perform other tasks while traveling, summon their vehicles from a distance, and send vehicles off to complete tasks without them. These travel behaviors could lead to increases in vehicle miles traveled that will have major implications for traffic congestion and pollution. To estimate the extent to which travel behavior will change, researchers and planners have typically relied on adjustments to existing travel simulations or on surveys asking people how they would change their behavior in a hypothetical autonomous vehicle future. Researchers at UC Berkeley and UC Davis used a new approach to understand the potential influence of autonomous vehicles on travel behavior by conducting the first naturalistic experiment mimicking the effect of autonomous vehicle ownership. Private chauffeurs were provided to 43 households in the Sacramento, California region for one or two weeks. By taking over driving duties for the household, the private chauffeurs served the household as an autonomous vehicle would. Researchers tracked household travel prior to, during, and after the week(s) with access to the chauffeur service.

Cover page of Wildfire Evacuation Planning Can Be Greatly Enhanced by Considering Fire Progression, Communication Systems, and Other Dynamic Factors

Wildfire Evacuation Planning Can Be Greatly Enhanced by Considering Fire Progression, Communication Systems, and Other Dynamic Factors

(2021)

Wildfires have become a perpetual crisis for communities across California. For life-threatening wildfires, mass evacuation often becomes the only viable option to protect lives. Yet, looking back at recent events, including the devastating 2018 Camp Fire in Northern California, there are significant challenges associated with the evacuation process, such as multi-agency coordination, agency-resident communication, and management of extraordinarily high amounts of traffic within a short period of time. Currently, emergency planners use evacuation models that are typically based on existing traffic simulation models; however, it is increasingly clear that other factors need to be considered, such as fire progression and communication systems. To address this gap, UC Berkeley researchers constructed a framework and set of models that include the combined impacts of three dynamic processes on evacuations – fire progression, communication systems, and traffic flow. The framework and models were applied to two case studies in California: the town of Paradise and the unincorporated community of Bolinas. In the Paradise case, the scenarios were based on the 2018 Camp Fire event. For the Bolinas case, the scenarios were based on hypothetical wildfire events.

Cover page of How is the COVID-19 Pandemic Shifting Retail Purchases and Related Travel in the Sacramento Region?

How is the COVID-19 Pandemic Shifting Retail Purchases and Related Travel in the Sacramento Region?

(2021)

A significant portion of the population stayed, and continue to stay, at home due to the COVID-19 pandemic. With more people staying home, online shopping increased along with trips related to pickups and deliveries. To gain a better understanding of the change in retail purchases and related travel, UC Berkeley researchers compared pre-pandemic shopping to pandemic-related shifts in consumer purchases in the greater Sacramento area for nine types of essential and non-essential commodities (e.g., groceries, meals, clothing, paper products, cleaning supplies). In May 2020, the research team resampled 327 respondents that participated in the 2018 Sacramento Area Council of Governments (SACOG) household travel survey. The 2018 SACOG survey collected responses over a rolling six-week period from April to May 2018 and asked residents about their motivations for, attitudes toward, and ease of use of online shopping. They were also were asked about the number of e-commerce purchases made, and the number of deliveries and pickups made from those e-commerce purchases for each commodity type. In addition, respondents also reported changes (less or more) in their behavior from a typical week in January or February 2020 (prior to the COVID-19 pandemic) for: 1) tripmaking, e-commerce purchases, and delivery and pick up frequencies; 2) purchase sizes; 3) distances traveled; and 4) modes used for in-person trips. This brief highlights findings from an analysis on changes in frequency of purchases, deliveries and pickups, and order sizes.

Cover page of Public Transit and Shared Mobility COVID-19 Recovery: Policy Options and Research Needs

Public Transit and Shared Mobility COVID-19 Recovery: Policy Options and Research Needs

(2020)

While the COVID-19 crisis has devastated many public transit and shared mobility services, it has also exposed underlying issues in how these services are provided to society. As ridership drops and revenues decline, many public and private providers may respond by cutting service or reducing vehicle maintenance to save costs. As a result, those who depend on public transit and shared mobility services, particularly those without access to private automobiles, will experience further loss of their mobility. These transportation shifts will be further influenced by changing work-from-home policies (e.g., telework). While uncertainty remains, work-from-home will likely alter public transit and shared mobility needs and patterns, necessitating different services, operation plans, and business structures.

Cover page of COVID-19 has Significantly Impacted the Mobility and Activities of the Senior Population in Contra Costa County

COVID-19 has Significantly Impacted the Mobility and Activities of the Senior Population in Contra Costa County

(2020)

Meeting the mobility needs of an aging population is one of the most substantial challenges facing California in the coming decades. The number of residents age 60 and above will grow to 13.9 million by 2050, representing over 25% of the state population. Meanwhile, the number of residents age 85 and above is expected to increase by over 70% between 2010 and 2030. In 2018, the Safe Transportation Research and Education Center (SafeTREC) at UC Berkeley conducted a survey on transportation mobility issues among older adults in Contra Costa County in California. Results indicated, among other findings, that a majority of seniors are car dependent, that some older adults miss important activities due to mobility limitations, and that most older adults want to “age in place.” A follow-up survey of 302 Contra Costa County seniors ages 60 and above was conducted in June 2020, just as the COVID-19 pandemic changed life for all residents. The follow-up survey assessed the mobility needs and changes during the Shelter-in-Place order as well as how COVID-19 was impacting other areas of their lives, such as their economic situation, views of government regulatory efforts, feelings of social isolation, and work/employment status. This brief presents findings from the follow-up survey.

Cover page of UC Berkeley Develops New User-Friendly Tool to Expedite the Evaluation of Connected Automated Vehicle Technologies

UC Berkeley Develops New User-Friendly Tool to Expedite the Evaluation of Connected Automated Vehicle Technologies

(2020)

Connected Automated Vehicles (CAVs) are similar to other automated vehicles with the distinguishing difference being that CAVs obtain information about road conditionsdirectly from other vehicles and infrastructure (e.g., traffic signals, road sensors) rather than relying solely on onboard sensors. Different CAV technologies are currently being tested and evaluated to assess the prospects for future implementation. These tests involve moving CAV-equipped vehicles on a physical test track and recording how the vehicles operate under different traffic conditions (Figure 1). Since it is difficult and expensive to recreate multiple real-world driving conditions on a single test track, virtual environments are typically used to simulate different traffic conditions, such as traffic signal operation, actions by other vehicles on the road, and other scenarios. These virtual hardware-in-the-loop (HIL) tests can expedite CAV performance evaluation and inform future system implementation; however, existing HIL test systems often lack the ability to manage large amounts of test data, which limits the value and use of these tests.

Cover page of The Benefits and Challenges of Incorporating Uber and Lyft in Subsidized Ride Programs that Serve Vulnerable Populations

The Benefits and Challenges of Incorporating Uber and Lyft in Subsidized Ride Programs that Serve Vulnerable Populations

(2020)

Cities, transit agencies, and social service providers across the U.S. have implemented programs that provide taxi subsidies for people who have difficulty driving a car or using the regular transit system. These programs usually serve older residents and people with disabilities, though a few also serve low income users. Taxi subsidy programs provide curb-to-curb or door-to-door transportation at a fraction of the cost of paratransit.1 However, as Transportation Network Companies (TNCs), such as Uber and Lyft, have entered markets around the country, taxi availability has declined, resulting in lower levels of service. In response, many public agencies are considering the addition of TNCs to subsidized ride programs; however, the inclusion of TNCs in these programs is not straightforward. For example, agencies must evaluate the extent to which their clients need wheelchair accessible vehicles or other personal assistance. In addition, TNC platforms require users to request rides through a smartphone and use debit or credit cards for payment, which is problematic for unbanked customers and those who do not own or have access to a smartphone.