research report

Evaluating Road Resilience to Wildfires: Case Studies of Camp and Carr Fires

Abstract

Between 2017 and 2018, California experienced four devastating fires, including the Camp and Carr Fires. After fires, road infrastructure is crucial for safe removal of hazardous materials and waste to landfills and recycling facilities. Despite the critical role of pavements in this process, there has been little quantitative evaluation of the potential damage to pavements fromtruck traffic for debris removal. To address this knowledge gap, data on truck trip numbers and debris tonnage following the Camp and Carr Fires were used to calculate changes in equivalent single axle loads and traffic index over the pavement’s design life(the age at which reconstruction would be considered). Simulations were conducted on existing pavement structures to assess potential additional damage based on increased traffic indices. Pavement structural design simulations showed that out of the nine studied highways, one exhibited a reduction in cracking life of about two years from debris removal operations. However, fatigue cracking was significantly accelerated for Skyway, the major road in the Town of Paradise, failing 14.3 years before its design life. A methodology similar to the one presented in this study can be adopted in debris management planning to strategically avoid vulnerable pavements and minimize damage to the highway network

published journal article

Evaluating Road Resilience to Wildfires: Case Studies of Camp and Carr Fires

Abstract

Between 2017 and 2018, California experienced four devastating fires, including the Camp and Carr Fires. After fires, road infrastructure is crucial for safe removal of hazardous materials and waste to landfills and recycling facilities. Despite the critical role of pavements in this process, there has been little quantitative evaluation of the potential damage to pavements from truck traffic for debris removal. To address this knowledge gap, data on truck trip numbers and debris tonnage following the Camp and Carr Fires were used to calculate changes in equivalent single axle loads and traffic index over the pavement’s design life (the age at which reconstruction would be considered). Simulations were conducted on existing pavement structures to assess potential additional damage based on increased traffic indices. Pavement structural design simulations showed that out of the nine studied highways, one exhibited a reduction in cracking life of about two years from debris removal operations. However, fatigue cracking was significantly accelerated for Skyway, the major road in the Town of Paradise, failing 14.3 years before its design life. A methodology similar to the one presented in this study can be adopted in debris management planning to strategically avoid vulnerable pavements and minimize damage to the highway network.

research report

Effects of Road Collisions on the Travel Behavior of Vulnerable Groups: Expert Interview Findings

Abstract

The research team interviewed eight subject-matter experts in California in 2023 to understand how travel behavior and priorities may change in response to direct experience with road collisions. Experts represented a variety of perspectives, including medical doctors, advocates for active transportation safety, and advocates for people with disabilities. Their diverse specialties enabled us to capture a variety of concerns without triggering emotionally sensitive areas for people who have directly experienced road collisions. These experts identified common themes, including mental stress from the prospect of returning to driving—especially on freeways, lesser incidence of long-term changes in travel modes after experiencing a collision, dependence on others for rides in private vehicles, and changing routes or times of day of travel when traveling independently. These experts also explained how people’s mode choices are also affected by general concerns about collisions in the news more than by specific personal experiences with near misses. Interview subjects’ spoke of more specific concerns as well. These included but were not limited to, bicyclists using sidewalks instead of bike lanes when both are present, feeling stigmatized from using public transit or paratransit after experiencing a collision, and concerns with motorists treating bicyclists badly. These initial interviews clarify areas of focus and methodology for future qualitative and quantitative studies on the intersection of transportation safety and travel behavior change, particularly as they involve people who have directly experienced road collisions.

published journal article

Emissions of Electric Vehicles in California’s Transition to Carbon Neutrality

Abstract

California has many activities targeting specific sectors to mitigate climate change. This study models several scenarios of future electric vehicle emissions in the state and explores untapped policy opportunities for interactions between sectors, specifically between the transportation and 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 of charging patterns can be a potentially important resource to alleviate issues such as renewable intermittency. This study involved the creation of a model to predict the potential emissions benefits of managed vs. unmanaged charging. The study finds that the lion’s share of emissions reduction in the light-duty transportation sector in California comes from electrification, with a cumulative 1 billion tons of CO2 reduction through 2045. This figure represents a decrease of about 4 tons CO2/capita/year from the average operation of Californian passenger vehicles in 2020 to about 40 kg CO2/capita/year in 2045. Decarbonization of the current grid leads to an additional savings of 125 million tons of CO2 over the same time period. As the state moves towards these objectives through existing (and potential future) policies, additional policies to exploit synergies between transportation electrification and grid decarbonization could reduce cumulative emissions by another 10 million tons of CO2.

research report

An Integrated Corridor Management for Connected Vehicles and Park and Ride Structures using Deep Reinforcement Learning

Abstract

The upcoming Connected Vehicles (CV) technology shows great promise in effectively managing traffic congestion and enhancing mobility for users along transportation corridors. Data analysis powered by sensors in Connected Vehicles allows us to implement optimized traffic management strategies optimizing the efficiency of transportation infrastructure resources. In this study, the research team introduces a novel Integrated Corridor Management (ICM) methodology, which integrates underutilized Park-And-Ride (PAR) facilities into the global optimization strategy. To achieve this, the team uses vehicle-to-infrastructure (V2I) communication protocols, namely basic safety messages (BSM) and traveler information messages (TIM) to help gather downstream traffic information and share park and ride advisories with upstream traffic, respectively. Next, the team develops a model that assesses potential delays experienced by vehicles in the corridor. Based on this model, the research team employs a novel centralized deep reinforcement learning (DRL) solution to control the timing and content of these messages. The ultimate goal is to maximize throughput, minimize carbon emissions, and reduce travel time effectively. To evaluate the Integrated Corridor Management strategy, the paper includes simulations on a realistic model of Interstate 5 using the Veins simulation software. The deep reinforcement learning agent converges to a strategy that marginally improves throughput, travel speed, and freeway travel time, at the cost of a slightly higher carbon footprint.

preprint journal article

Patterns in Bike Theft and Recovery

Publication Date

September 1, 2023

Author(s)

Dillon Fitch-Polse, David Nelson, Achituv Cohen, Trisalyn Nelson, Lizzy Schattle

Abstract

Our goal is to reduce the negative impacts of bicycle theft by better understanding patterns in bicycle theft and recovery. The research team analyzed data from 1823 responses to a North American survey on bicycle theft conditions, recovery circumstances, and demographics. Survey recruitment was done in partnership with BikeIndex, a non-profit bicycling registration service. Most bikes were stolen from inside a shed or garage (28%) or from outdoor bicycle racks (18%) and most thefts occur overnight (41%). 15% of stolen bicycles were recovered. Key factors in recovery include police involvement, bike registration, and reporting the theft through multiple channels.

published journal article

Who Lives in Transit-friendly Neighborhoods?: An Analysis of California Neighborhoods over Time

Publication Date

June 1, 2021

Author(s)

Julene Paul, Brian D. Taylor

Abstract

In this paper, we examine social and economic trends in California’s transit-friendly neighborhoods since 2000. In particular, we explore the relationship between high-propensity transit users – who we define here as members of households classified as poor, immigrant, African-American, and without private vehicles – and high-transit-propensity places – which are neighborhoods that regularly host high levels of transit service or use. As housing costs have increased dramatically in California and neighborhoods change, many planners and transit advocates reasonably worry that in transit-friendly neighborhoods, lower-propensity transit users may replace residents who tend to ride transit frequently. Such changes in residential patterns could help to explain sharp transit ridership declines in California in the 2010s ahead of much sharper pandemic-related ridership losses in 2020. Indeed, we find that California’s most transit-friendly neighborhoods have changed in ways that do not bode well for transit use. The state’s shares of poor, immigrant, African American, and zero-vehicle households have all declined modestly to substantially since 2000. Collectively, these trends point to changes in California’s most transit-friendly neighborhoods that are not very, well, transit-friendly.

published journal article

Jobs-housing Balance Re-re-visited

Publication Date

May 19, 2021

Author(s)

Evelyn Blumenberg, Hannah King

Abstract

Problem, research strategy, and findings:
In many U.S. metropolitan areas, housing costs have skyrocketed in recent years relative to average incomes. A worsening shortage of affordable housing in these metros may push households away from job-rich cities and expensive neighborhoods into outlying areas, where housing is cheaper but jobs are more distant. To examine this issue, we revisit the jobs-housing balance, a popular topic of research in the 1990s, with a focus on the relationship between housing and the spatial location of workers relative to jobs. Our analysis draws on data from the Longitudinal Employer-Household Dynamics Origin-Destination Employment Statistics (LODES) for cities in California in 2002 and 2015. In contrast to earlier jobs-housing balance research, we find that California cities are becoming less self-contained over time, defined as a decline in the number of workers who both live and work within a jurisdiction relative to the number of commuters who travel either into or out of a city for work. Statistical models show that self-containment was higher in cities with lower housing costs and, in 2015, in cities with a greater balance between jobs and employed residents.

Takeaway for practice:
The deepening housing affordability crisis in many metropolitan areas like those found in California is pushing workers and jobs farther apart, increasing the economic, social, and environmental costs of commuting. Policies to increase the supply of housing in job-rich and high–housing cost areas could help reverse this troubling trend, though they are likely to meet with considerable resistance. Our findings also underscore the importance of efforts that include but extend beyond housing production, such as policies to better match job skills and housing prices to the characteristics of workers.

published journal article

"It Is Our Problem!": Strategies for Responding to Homelessness on Transit

Abstract

Buses, bus stops, trains, and train platforms represent sites of shelter for many of the over 500,000 Americans who are unhoused every night. This study seeks to understand how transit agencies are responding to them. Based on interviews with staff members and partners at 10 different transit agencies and on program performance data, where available, we provide detailed case studies of four sets of strategies taken in response to homelessness in transit systems: a hub of services, mobile outreach, discounted fares, and transportation to shelters. We analyze each strategy’s scope, implementation, impact, challenges, and lessons learned. Reviewing these strategies, we note that they may differ depending on the context, need, and available resources. We find value in transit agencies fostering external partnerships with social service organizations and other municipal departments and keeping law enforcement distinct from routine homeless outreach. We also underline the key need for funding from other levels of government to allow transit operators to adopt, expand, and refine homelessness response programs.

book/book chapter

LOST and Found: The Fall and Rise of Local Option Sales Taxes for Transportation in California amidst the Pandemic

Abstract

The COVID-19 pandemic dramatically affected the ability of localities to pay for their transportation systems. We explore the effects of the pandemic 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, including that they can raise prodigious amounts of revenue. However, LOSTs rely on consumer spending, which lags during times of economic weakness. This is precisely what we observed in California counties during the initial months of the pandemic. LOST revenues did recover after the initial economic shock of COVID-19, albeit to a lower level than they would likely 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 crises and associated economic turbulence.