research report

Synergies of Combining Demand- and Supply-Side Measures to Manage Congested Streets

Abstract

An agent-based, multichannel simulation of a downtown area reveals the impacts of both redistributing traffic demand with time-dependent congestion pricing, and supplying extra capacity by banning left turns. The downtown street network was idealized and loosely resembles central Los Angeles. On the demand side, prices were set based on the time of day and distance traveled. On the supply side, left-turn maneuvers were prohibited at all intersections on the network. Although both traffic management measures reduced travel costs when used alone, the left-turn ban was much less effective than pricing. When combined with pricing under congested conditions, however, the left-turn ban’s effectiveness increased considerably—it more than doubled in some cases. Furthermore, the two measures combined reduced travel costs in synergistic fashion. In some cases, this synergistic effect was responsible for 30% of the cost reduction. This strong synergy suggests that turning bans should be considered as an added option when contemplating congestion pricing.

dataset

Open-source Code for Street Network Geometry Projects – Global and California

Abstract

Open-source code to allow other researchers to extend the analysis: https://github.com/amillb/streetwidths

Please reach out to the project Principal Investigator for more information.

website

streetwidths.its.ucla.edu

Abstract

The width of street rights-of-way is normally determined by traffic engineering and urban design conventions, without considering the immense value of the underlying land. This storyboard discusses the regulations around street width.

Please reach out to the Principal Investigator for more information on this website.

policy brief

A Mobile and Cost-Effective Computational Technology to Analyze Brake and Tire Wear Emissions

Abstract

Researchers developed a portable computational imaging and deep-learning enhanced aerosol analysis device (c-Air) to identify and measure particulate emissions directly from traffic sources. Researchers found that significantly higher numbers of particles were collected per second when the car was in motion compared to the background particle levels measured when the vehicle was stationary. In addition, even more particles were generated during acceleration and braking. This mobile and cost-effective device is able to distinguish non-volatile as well as volatile and evaporating particles caused by brake and tire wear generated by a moving vehicle from background road dust, with a high degree of accuracy in the field. In addition to counting and sizing particles, this system can also classify particles based upon physical features, shape, color and volatility using computational imaging and deep learning.

policy brief

Smart Charging of Electric Vehicles Will Reduce Emissions and Costs in a 100% Renewable Energy Future in California

Abstract

California has goals of achieving 100% renewable energy by 2045 and 100% zero-emission vehicle sales by 2035. Electric vehicles will introduce significant new demand for electricity at the same time the state’s electricity grid is incorporating more intermittent energy sources, raising concerns about grid reliability. However, the flexibility of electric vehicle charging provides a potentially powerful asset in mitigating the challenges of a renewable energybased electricity grid. Smart charging—adapting electric vehicle charging based on the conditions of the power system and the needs of the vehicle user—can take advantage of this flexibility by charging vehicles when renewable energy is readily available. Researchers at UC Davis simulated 100% electric vehicle adoption and a 100% renewable energy-powered electricity grid by 2045 in California. They then compared a scenario of regular electric vehicle charging behavior with a scenario of advanced, flexible, smart charging under which charging is aligned with renewable energy availability, to understand how smart vehicle charging could benefit the electricity grid.

research report

Spatial Modeling of Future Light- and Heavy-Duty Vehicle Travel and Refueling Patterns in California

Abstract

A spatial optimization model was developed for deploying, over the next two decades, hydrogen refueling stations for heavy-duty zero-emission hydrogen vehicles. The model assigns trips to vehicles by applying a routing algorithm to travel demand data derived from another model—the California Statewide Travel Demand Model (developed by the California Department of Transportation). Across a range of adoption levels of hydrogen fuel-cell truck technology, from 2020 through 2030, the results suggest that heterogeneity of travel demand may necessitate an extensive distribution of refueling stations, which may lead to low utilization of stations in the short term. To efficiently employ the capacity of stations, a certain volume of vehicle adoption must be met, and/or truck routes must be planned and committed to specific roadways. Once the number of stations reaches a threshold to meet the principal demand in affected transportation area zones, a small set of smaller “top-off” stations can be built to meet marginal excess demand. The best location of a hydrogen refueling station within a transportation area zone also depends on criteria such as land cover, slope, and distance from gas stations, truck hubs, and the truck network.

research report

All Is Not LOST: Tracking California’s Local Option Sales Tax Revenues for Transportation During the Pandemic

Abstract

The COVID-19 pandemic dramatically affected transportation systems, including the ability of localities to pay for them. The research team explores the effects of the pandemic and the associated economic turbulence on local option sales taxes (LOSTs), an increasingly common revenue source for transportation in California and across the U.S. LOSTs have many advantages over alternative finance instruments, and they can raise prodigious amounts of revenue. However, LOST funding relies on consumer spending. During times of economic weakness, spending and therefore LOST revenues will lag. This is precisely the pattern the team observed in California counties during the initial months of the pandemic. Fortunately for local transportation budgets, LOST revenues recovered after the initial economic shock of COVID-19, albeit at a lower level than they likely would have otherwise. LOST revenue trends during the pandemic were affected by national and regional economic conditions and government policy as well. This public health crisis illustrates both the pitfalls and resilience of LOSTs during economic downturns and recoveries. The lessons from the pandemic’s effects on LOSTs will be useful for policymakers and analysts in preparing for inevitable future economic fluctuations.

research report

Green Charging of Electric Vehicles Under a Net-Zero Emissions Policy Transition in California

Abstract

California has many aggressive climate policies, primarily aimed at individual sectors. This study explores untapped policy opportunities for interactions between sectors, specifically between the transportation and the electricity grid. As electric vehicles become more prevalent, their impact on the electricity grid is directly related to the aggregate patterns of vehicle charging. Even without vehicle-to-grid services, shifting charging patterns can be a potentially important resource to alleviate issues such as renewable intermittency. This study compares, through modeling, projected emissions reductions from managed vs. unmanaged charging. The majority of emissions reduction in the light-duty transportation sector in California will come from electrification, with a cumulative 1 billion tons of CO2 reduction through 2045. Decarbonization of the current grid leads to an additional savings of 125 million tons of CO2 over the same time periodotential state policies to exploit synergies between transportation electrification and grid decarbonization could reduce cumulative emissions by another 10 million tons of CO2. These policies include strategic deployment of charging infrastructure, pricing mechanisms, standardizing grid interaction protocols, and supporting grid infrastructure requirements.

policy brief

Bike-Share in the Sacramento Region Primarily Substitutes for Car and Walking Trips and Reduces Vehicle Miles Traveled

Abstract

Dock-less, electric bike-share services offer cities a new transportation option with the potential to improve environmental, social, and health outcomes by increasing physical activity and reducing vehicle miles traveled (VMT) and related greenhouse gas emissions. But these benefits accrue only if bike-share use replaces car travel. If bikeshare pulls users from public transit, personal bikes, or walking, the benefits will be limited. Little is known about the factors influencing whether bike-share substitutes for driving. Understanding the degree to which and under what circumstances bike-share use reduces car travel can inform cities’ efforts to meet VMT reduction goals set under California’s Sustainable Communities and Climate Protection Act of 2008 (Senate Bill 375). Researchers at the University of California, Davis collected user surveys and system-wide trip data from a Sacramentoarea dockless e-bike-share program in 2018 and 2019 to examine factors influencing travel mode substitution and estimated system-wide VMT reductions caused by bikeshare use. They developed a model to examine factors influencing bike-share demand and estimated potential VMT reductions for hypothetical expanded service scenarios.

research report

Where Ridehail Drivers Go Between Trips: Trading off Congestion and Curb Availability?

Abstract

The research team analyzed what ride-hail drivers do when out of service between paid trips. The paper utilizes a dataset of 5.3 million trips in San Francisco and partitions each out-of-service trip into cruising, repositioning, and parking segments. We find that repositioning accounts for nearly two-thirds (63%) of the time between trips, with cruising and parking accounting for 23% and 14% respectively (these figures exclude short trips). The regression models suggest that drivers tend to make reasonable choices between repositioning and parking, heading to high-demand locations based on the time of day. However, we also find suggestive evidence of racial bias, supporting previous studies of both taxis and ride-hailing that indicate that drivers tend to avoid neighborhoods with high proportions of residents of color.