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Open Access Publications from the University of California
Cover page of Smart Algorithms to Increase Rail Capacity in Congested Areas

Smart Algorithms to Increase Rail Capacity in Congested Areas

(2019)

Railway has always been an effective mode to transport both people and goods. Freight trains are about four times more fuel efficient than trucks and passenger trains and are popular because of their blend of efficiency, speed and low emissions. Increasing rail network capacity, however, can be difficult and expensive. Finding more efficient ways to utilize existing rail network capacity can mitigate the impacts of growing freight demand. 

New communication technologies, such as Positive Train Control (PTC), have the potential to improve efficiency and minimize delays in freight and passenger railway operations. PTC enables trains to communicate and share critical information such as speed and location with each other in real time. This research brief highlights findings from the project, "Integrated Management of Truck and Rail Systems in Los Angeles," which simulated the complex, busy freight and passenger rail corridor between downtown Los Angeles and Pomona to evaluate the effectiveness of proposed new scheduling and dispatching algorithms using PTC.

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Cover page of Estimating Fuel-Saving Impact of Low Rolling Resistance Tires on Heavy-Duty Vehicle Fleet Operations

Estimating Fuel-Saving Impact of Low Rolling Resistance Tires on Heavy-Duty Vehicle Fleet Operations

(2019)

The U.S. Environmental Protection Agency identified the use of low rolling resistance (LRR) tires as an effective method of reducing vehicle fuel consumption, especially from heavyduty vehicles (HDV). LRR tires are important to HDV operations because fuel accounts for about 25% of operating costs, and improving fuel economy also reduces emissions of both greenhouse gases and oxides of nitrogen, a precursor to the formation of ozone, which is harmful to humans, plants, and animals. However, their adoption rate has been slow primarily due to performance uncertainties under real-world operating conditions. Previous mathematical models developed to help fleet operators estimate the impact of LRR tires on their operations have suffered from poor accuracy because they do not account for variable speed profiles in realworld HDV operations. Georgia Tech researchers have developed a new tool for fleet managers that better predicts the benefits of LRR tires under real-world conditions.

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Cover page of The State of Electric Vehicle Markets, 2017: Growth Faces an Attention Gap

The State of Electric Vehicle Markets, 2017: Growth Faces an Attention Gap

(2019)

Ambitious global goals to improve energy efficiency and reduce greenhouse gas emissions are motivating a shift to electric vehicles (EVs), which include battery-electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles. In 2018, the governor of California called for five million EVs to be on California’s roads by 2030. The International Energy Agency projects a global increase in EVs from 2 million today to 280 million by 2040. Creating sustained market growth to meet such goals presents numerous challenges to all EV stakeholders, including governments, the automobile industry, electricity suppliers, non-governmental organizations, and consumers.

This policy brief summarizes the latest in a series of recurring surveys of consumers regarding their awareness and consideration of EVs. Two surveys of the population of car-owning households in California were conducted in February and June of 2017; sample sizes were 1,681 and 1,706, respectively. Several survey questions have been repeated over multiple years in similar samples, allowing comparison to earlier results.

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Cover page of Average Impact and Key Features of Onboard Eco-driving Feedback

Average Impact and Key Features of Onboard Eco-driving Feedback

(2019)

Driver behavior has a significant impact on vehicle fuel economy and emissions. Eco-driving refers to anything a driver can do to improve on-road fuel economy. The most common strategy used to promote eco-driving is an in-vehicle display that provides the driver with feedback about their fuel efficiency, typically in real-time.

This policy brief summarizes findings from an extensive review and analysis of many studies of eco-driving feedback conducted to determine the average impact of feedback on fuel economy and improve understanding of what types of feedback are most effective. The study provides the most accurate estimate to-date of the average impact of in-vehicle feedback on fuel economy and summarizes the current state of knowledge regarding characteristics of eco-driving feedback interventions that determine effectiveness.

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Cover page of The Effects of Ride-Hailing Services on Greenhouse Gas Emissions

The Effects of Ride-Hailing Services on Greenhouse Gas Emissions

(2019)

Ride-hailing services, which allow consumers to order and pay for rides through smart phone applications, have grown to a substantial proportion of the transportation market. Today, an estimated 15% of adults across the U.S. and 21% living in major U.S. cities have used ride-hailing services. The growth of ride-hailing services has raised questions about their overall effects on the transportation system. While they clearly offer a new form of mobility, there is concern they may increase congestion and air pollutant emissions. A limited number of studies have attempted to quanitfy changes associated with the increased use of ride hailing services.

UC Davis researchers examined how ride-hailing affects the total amount of driving (measured in vehicle miles traveled, VMT) as well as greenhouse gas (GHG) emissions. The researchers developed a framework of categories for analyzing the multiple aspects of transportation that may be affected by ride-hailing. These categories are: automobile ownership; number of vehicle trips generated; choice of mode of travel; empty (passenger-less) travel between drop-off and pick-up points, known as “network travel”; and destination choice and land use. Thirteen (13) studies were analyzed using this new framework: 8 used surveys of riders or recorded data on rider and driver activity; and 5 used simulated (“modeled”) travel in and around cities by automated taxis. By compiling multiple studies in the framework, stronger and more certain conclusions could be reached.

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Cover page of Changing Workforce Development Needs for Regional Transportation Planning Agencies in California

Changing Workforce Development Needs for Regional Transportation Planning Agencies in California

(2019)

In California, Senate Bill 375 (SB 375, 2008) required each Metropolitan Planning Organization (MPO) to develop a Sustainable Communities Strategy (SCS). This mandate required MPOs to set targets and develop strategies to reduce transportation-related greenhouse gas emissions within their region. To deliver effectively on this policy, there has been an amplified need for a workforce with both technical and functional skills.

In the context of MPOs, technical (or technological) skills include the use of intelligent transportation systems, new engineering practices, and modeling (using mathematical formulas to represent and predict the impact of multiple actions by many people on transportation or air quality, etc.). Functional skills include public outreach, communications, stakeholder engagement, and leadership.

This policy transition was made more difficult by rising retirement rates within the public sector and the growth of intelligent technologies being used in the workplace. By 2020, 16.5% to 20% of the entire workforce in the United States will be 65 or older and, in the transportation sector, this percentage is even higher. Many of the important technical and functional skills for the modern planning workforce require a facility with information technology, modeling software, social media, and outreach that were not typically developed in the past.

In this research, MPOs were approached through surveys and in-depth interviews, with questions on changes in their processes and workforce needs due to various factors, including the requirements of SB 375.

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Cover page of Electrifying Ride-Sharing: Transitioning to a Cleaner Future

Electrifying Ride-Sharing: Transitioning to a Cleaner Future

(2019)

Incentives for plug-in electric vehicles (PEVs) are typically designed to encourage broad consumer adoption of the new technology. However, maximizing the emissions benefits from electrifying the transportation sector also requires incentives targeted at stakeholders with high travel intensity, i.e., those with particularly high passenger occupancy and/or vehicle-miles traveled (VMT). This policy brief focuses on one such class of stakeholders: transportation network companies (TNCs) such as Uber and Lyft. It examines empirical data of electric vehicle use in TNCs and discusses research findings on the potential impacts of electrifying TNCs. It also raises important considerations for the development of future policy.

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Cover page of Vermont Agency of Transportation Employee Retention and Knowledge Management Study

Vermont Agency of Transportation Employee Retention and Knowledge Management Study

(2019)

Employee retention is a critical issue for organizations of all types. Public sector groups such as the Vermont Agency of Transportation (VTrans) are no exception. Not only can the costs of recruitment, training, and orientation approach 100% of the annual salary for the position being filled, but work disruption and loss of organizational memory can impact organization performance. Vermont is not alone in facing a transportation workforce challenge. A recent publication from the National Cooperative Highway Research Program for state departments of transportation stresses the importance of knowledge management (KM) in these organizations and provides guidelines for enhancing retention and talent management, two key issues to an effective workforce. As the report acknowledges, the constraints of retirements, departing mid-career employees, and the changing workplace expectations of the millennial generation all play into an organization that may face a steady decline in resilience, unless a clear plan is in place to address retention and implement KM practices. Recognizing these critical issues, VTrans leaders embraced an applied research project intended to assess the state of both retention and KM at the agency and develop pilot projects to address both areas. This policy brief summarizes the findings of that study.

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Cover page of Travel Effects and Associated Greenhouse Gas Emissions of Automated Vehicles

Travel Effects and Associated Greenhouse Gas Emissions of Automated Vehicles

(2018)

Automated vehicles (AVs) may significantly disrupt our transportation system, with potentially profound environmental effects. This policy brief outlines the mechanisms by which AVs may affect the environment through influencing travel demand, as well as the magnitude of these effects on vehicle miles travelled (VMT) and greenhouse gas (GHG) emissions. Personal AVs and AV taxis (or ride-hailing services) are likely to increase VMT and GHG, exacerbate traffic congestion in city centers, and potentially lead to suburban sprawl. Electrification and vehicle sharing may reduce some of these environmental effects, but targeted policies must be put in place to ensure that these solutions are effective.

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Cover page of Advancing Understanding of Long-Distance and Intercity Travel with Diverse Data Sources

Advancing Understanding of Long-Distance and Intercity Travel with Diverse Data Sources

(2018)

The relative share of passenger miles of travel undertaken during non-routine out-of-town longer-distance trips is large (potentially 30% or higher) and growing. Research on long-distance travel, whether by surface or air modes, has been limited in the United States by lack of data, in part because household travel survey data focuses on daily routine travel. Planners will need to take long-distance travel and its associated impacts into consideration if they hope to address policy questions related to transportation system sustainability. These impacts include environmental degradation from greenhouse gasses and other emissions, and raise challenging questions about who “owns” or is associated with these emissions. Equity impacts include the relationship between travel and quality of life. Intercity travel provides access to employment, education, and experiential opportunities. It also provides access to increasingly large and geographically dispersed social networks and the important face-to-face interactions with family, friends, and colleagues.

This policy brief summarizes findings from the project, which had two main research questions. First, what is the best way to measure individuals’ long-distance travel in order to inform planning and policy? Second, what factors are associated with long-distance travel and do they suggest inequitable access to intercity and more distant destinations? This project relied on several innovative existing datasets, original interviews, and a unique survey of travel and social network geography.

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