white paper

Reduce Emissions and Improve Traffic Flow Through Collaborative Autonomy

Abstract

This report explores opportunities for employing autonomous driving technology to dampen stop-and-go waves on freeways. If successful, it could reduce fuel consumption and emissions. This technology was tested in an on-road experiment with 100 vehicles over one week. Public stakeholders were engaged to assess the planning effort and feasibility of taking the technology to the next level: a pilot involving 1000+ vehicles over several months. Considerations included the possible geographical boundaries, target fleets of vehicles, and suitable facilities such as bridges or managed lanes. Flow smoothing technology may improve the user experience and operations of managed lanes or bridges, however, it may require external incentives such as reduced tolls to entice the traveling public to use it. This must be matched with other goals such as verifying vehicle occupancy. It might be possible for some hybrid solution that addresses both challenges to provide a way forward. A concept of operations needs to be developed specifically for a target road geometry and a California partner. This concept should benefit from lessons learned from previous pilot projects and will need to be defined so as to achieve both (1) a penetration rate sufficient to achieve measurable effects; and (2) sufficient quality and quantity of data to confirm benefits.

policy brief

Connected Vehicle Technology and AI Could Help Reduce Highway Congestion through Better Utilization of Park and Ride Facilitie

Abstract

Considerable advancements have been made in traffic management strategies to address highway congestion over the past decades; however, the continuous growth of metropolitan regions has impeded such progress. In response, transportation planners have given special attention to integrated corridor management (ICM), an approach that coordinates various traffic control units (e.g., ramp metering) to optimize their operations along the entire freeway. Emerging connected vehicle (CV) technology is expected to substantially benefit ICM, where vehicles can communicate with each other and surrounding roadway infrastructure. The combined potential of ICM strategies and CVs could be even greater if combined with strategies that leverage underutilized infrastructure (specifically park-and-ride facilities) to reduce the total number of vehicles on the roadway.

research report

Reducing Congestion by Using Integrated Corridor Management Technology to Divert Vehicles to Park-and-Ride Facilities

Abstract

Connected Vehicles (CV) technology offers significant potential for managing traffic congestion and improving mobility along transportation corridors. This report presents a novel approach using integrated corridor management (ICM) technology to divert CVs to underutilized park-and-ride facilities where drivers can park their vehicle and access public transportation. Using vehicle-to-infrastructure (V2I) communication protocols, the system collects data on downstream traffic and sends messages regarding available park-and-ride options to upstream traffic. A deep reinforcement learning (DRL) program controls the messaging, with the objective of maximizing traffic throughput and minimizing CO2 emissions and travel time. The ICM strategy is simulated on a realistic model of Interstate 5 using Veins simulation software. The results show marginal improvement in throughput, freeway travel time, and CO2 emissions, but increased travel delay for drivers choosing to divert to a park-and-ride facility to take public transportation for a portion of their travel.

research report

Transport Pricing Policies and Emerging Mobility Innovations

Abstract

Transportation pricing policies aim to manage vehicular demand for parking, dense urban areas, roadways, and highway lanes. Although pricing policies take various forms, most were designed in a world before the sharing economy and ride-sourcing companies. Hence, the efficacy of existing pricing policies in a world with shared mobility services requires further consideration. Moreover, future pricing policies designed to handle private vehicles and shared ride-sourcing vehicles must consider the behavior of both sets of travelers and vehicle fleets. This study develops a conceptual framework to support systems-level analysis of pricing policies for a world with private and shared vehicle usage. It qualitatively analyzes the impact of shared vehicles on the effectiveness of various pricing policies, while also considering the role of vehicle-to-infrastructure technology. This conceptual framework will support future research that uses activity-based travel demand and dynamic network assignment models to evaluate congestion pricing policies in an era of shared mobility. Additionally, the study presents a detailed review of the literature related to transportation pricing together with a trend analysis on congestion pricing policies in Transportation Research Board annual meeting titles and abstracts.

policy brief

Transportation Network Companies Might Be Pulling Riders from Public Transit, but This Could Change

Abstract

Transportation Network Companies (TNCs, also known as ridehailing and ridesourcing) have expanded across California over the past decade and changed the way people travel. Using a smartphone, travelers can quickly summon a vehicle from almost anywhere and know what the estimated wait time, travel time, and cost will be before stepping into the vehicle. While TNCs are clearly addressing an unmet need for travelers, their growing popularity has raised a number of policy questions, including if TNCs are shifting people away from public transit and other travel modes (e.g., carshare, walking, biking).

research report

New Data and Methods for Estimating Regional Truck Movements

Publication Date

September 22, 2023

Author(s)

Abstract

This report describes how current methods of estimating truck traffic volumes from existing fixed roadway sensors could be improved by using tracking data collected from commercial truck fleets and other connected technology sources (e.g., onboard GPS-enabled navigation systems and smartphones supplied by third-party vendors). Using Caltrans District 1 in Northern California as an example, the study first reviews existing fixed-location data collection capabilities and highlights gaps in the ability to monitor truck movements. It then reviews emerging data sources and analyzes the analytical capabilities of StreetLight 2021, a commercial software package. The study then looks at the Sample Trip Count and uncalibrated Index values obtained from three weigh-in-motion (WIM) and twelve Traffic Census stations operated by Caltrans in District 1. The study suggests improvements to StreetLight’s “single-factor” calibration process which limits its ability to convert raw truck count data into accurate traffic volume estimates across an area, and suggests how improved truck-related calibration data can be extracted from the truck classification counts obtained from Caltrans’ weigh-in-motion and Traffic Census stations. The report compares uncalibrated StreetLight Index values to observed truck counts to assess data quality and evaluates the impacts of considering alternate calibration data sets and analysis periods. Two test cases are presented to highlight issues with the single-factor calibration process. The report concludes that probe data analytical platforms such as StreetLight can be used to obtain rough estimates of truck volumes on roadway segments or to analyze routing patterns. The results further indicate that the accuracy of volume estimates depends heavily on the availability of sufficiently large samples of tracking data and stable and representative month-by-month calibration data across multiple reference locations.

policy brief

How Are Transit Agencies in California Addressing the Travel Needs of People Experiencing Homelessness?

Abstract

Increasing numbers of people experiencing homelessness in California cities have prompted some transit agencies to address the needs of unhoused people and riders more comprehensively in their service plans. Some of these efforts respond to the presence of transit riders who are visibly homeless and seek shelter on transit vehicles, at transit stops, and on other agency property. Many people experiencing homelessness, however, are also active users of public transit, relying on buses and trains to access services, get to work, visit family, and more. Public transit is especially critical for those working to exit homelessness who do not have access to a personal vehicle.

research report

How Regional Transit Agencies Can Serve the Daily Mobility Needs of the Unhoused Population

Abstract

With more people experiencing homelessness in California cities, some transit agencies have begun to comprehensively address the needs of people experiencing homelessness, a population that historically may not have been included in their planning. Research suggests that people experiencing homelessness rely on public transit for the same variety of reasons that all riders do, and that, like other riders, they find it difficult to reach those destinations due to prohibitive costs and transit schedules that do not meet their needs. California transit agencies vary in terms of whether, and how well, they engage with the issue of homelessness. Interviews and a review of policy and programming documents show that most major transit agencies in California made some reference to people experiencing homelessness, but just ten of fifteen addressed their transit needs, and only three addressed those needs through dedicated programs. The research team uses this research synthesis to draw greater attention to the ways that transit agencies can serve the mobility needs of people experiencing homelessness. The team presents findings from a case study on transit accessibility in San Diego County to supplement the statewide review. This includes a geospatial analysis of transit accessibility from locations where people experiencing homelessness have been known to congregate in San Diego County, as well as interviews with three people who have experienced homelessness in the region and three advocates for the unhoused population. The team identifies the ways that transit accessibility is a complex issue, requiring consideration of proximity, ease of physical access, and programmatic support. Based on the research, the researchers recommend that transit and service organizations consider the following: (1) establish coordinated outreach in transit environments, (2) offer shuttles to services and employment to help one resolve their homelessness, (3) improve the reliability and connectivity of public transit, (4) support fare assistance programs, and (5) incorporate expertise from people with lived experience of homelessness.

policy brief

Low-Income Suburban Residents in the San Francisco Bay Area Face Significant Housing and Transportation Issues

Abstract

Growing poverty in America’s suburbs challenges their image as single-family residential communities for middle class, predominantly white families. Research shows that suburban areas now have the largest share of households under the poverty line. Since these areas have lower density development and lower levels of public transit service compared to urban areas, living in the suburbs may pose accessibility challenges for low-income households, particularly those without a personal vehicle. To explore housing and transportation issues associated with the suburbanization of poverty, we combined U.S. Census data from Contra Costa County, which has the highest rates of suburban poverty in the San Francisco Bay Area, and online and in-person surveys with individuals who earn less than 80% of the Area Median Income (AMI), around $75,000. This research identifies demographic and external factors that lead low- and moderate-income households to move to suburban areas, accessibility barriers faced by low- and moderate-income suburban households, and how transportation use and transportation and housing costs differ between urban and suburban low-income residents in the Bay Area.

research report

Struggling to Connect: Housing and Transportation Challenges of Low-Income Suburban Residents in the San Francisco Bay Area

Abstract

Suburban areas have lower density development than urban areas, which may make them less accessible for the growing population of low- and moderate-income suburban residents, particularly those without a personal vehicle. This research examines factors that lead these households to move to suburban areas and identifies accessibility barriers they face. We use a mixed-methods approach with Public Use Microdata Sample data from the U.S. Census, online/in-person surveys (n=208), and interviews conducted in English and Spanish (n=25) with households in Contra Costa County with an income of less than $75,000. To understand key differences in housing and transportation choices between urban and suburban residents, these data were compared to survey and interview data from low-income Oakland residents from 2020-2021. We found that low- and moderate-income households choose to live in the suburbs due to rising rents and other requirements (e.g., credit score, rental history) in urban areas, and a desire for home ownership and a safer environment for children. Yet, the lack of tenant protections is leaving them vulnerable to rising rents in suburban areas. Transportation costs are higher in suburbs due to longer commutes and higher reliance on personal vehicles. Despite higher levels of car-ownership in the suburbs, households often go without a car due to maintenance issues or inability to make car payments. When faced with the lack of an automobile, suburban households have few quality transportation alternatives.