Icon for peer review journal article preprint

published journal article

Co-designing a Bicycle Lending Library for Lower-income Communities in California

Abstract

Commercial bikeshare systems have expanded urban mobility but continue to present structural barriers for low-income and minority communities. This study examines how design attributes, sociodemographic characteristics, and perceived community strength shapes residents’ likelihood of adopting a Bike Lending Library (BLL) in lower-income neighborhoods across California. One such community at the heart of this study is Santa Ana, a densely populated and culturally vibrant urban center with majority Latino/Hispanic community located in Orange County. The study found lock provision, bike weight, and cost are strong determinants of BLL rental choice among low-income Californians. The ICLV model reveals that ‘perceived community strength’, operationalized through five indicators of civic engagement and organizational capacity, has a statistically significant positive effect on BLL adoption. Male respondents showed significantly higher rental likelihood while low-income households showed significantly lower likelihood. Thematic analysis identified cross-cutting themes of safety and infrastructure, program design, affordability, community motivation, and program enthusiasm that converged across all data sources. This study provides one of the first applications of the ICLV framework to a community-based bike lending program, revealing that social and psychological dimensions of community life may be meaningful predictors of shared mobility adoption in disadvantaged urban contexts. Findings produce actionable recommendations for BLL program design, siting, pricing, and outreach, and offer a replicable mixed-methods framework for community-centered active transportation planning.

Icon for peer review journal article preprint

published journal article

California Transportation Planning Tool for Statewide Data-Driven Optimization

Abstract

Estimating travel behavior parameters is essential for understanding current travel patterns and for forecasting how travelers may respond to future changes in transportation systems. However, reliable estimation remains difficult when behavior must be inferred from sparse and aggregate observations, especially when jointly recovering several behavioral components. In this paper, the research team developed a bi-level estimation program for a combined destination, mode and route choice model with congestion. The inner level is a convex program at given scale parameters, and returns the taste coefficients as its dual variables together with the equilibrium travel pattern. The outer level selects the scale parameters by out-of-sample prediction, measured by how well the modeled travel pattern predicts observations withheld from estimation. To solve the bi-level problem at scale, the research team proposed a matrix-free Hierarchical Lagrangian Dual algorithm as the inner solver and an outer search by implicit differentiation, which uses the sensitivities of the inner solution to enable efficient search over the scale parameters and reaches the calibrated scales in a handful of iterations. The research team validated the approach on Los Angeles County using public origin-destination, mode-share and traffic-count data. The approach scales to a county-level problem with 2.7 million variables and substantially improves computational efficiency over a general-purpose conic solver. Compared with the fixed-scale benchmark, the calibrated model improves predictive performance at the destination and mode levels, with consistent gains across complementary goodness-of-fit measures.

Icon of report

research report

GHG Emissions Reductions from CRP Projects

Publication Date

September 1, 2026

Author(s)

Qiao Yu, Junmei Cheng, Taylor DeRouen, Jiaqi Ma, Yifang Zhu

Abstract

The Carbon Reduction Program (CRP) requires transportation projects to demonstrate measurable reductions in transportation-related greenhouse gas (GHG) emissions, but the impact of priced managed lanes and related roadway pricing projects on emissions can vary. Thus, there is a need for a transparent framework that can place evidence within a common statewide emissions metric. This report develops a screening framework to translate project-level GHG impact data from CRP-relevant projects in California into a wider statewide framework for emissions accounting. The preliminary framework separates the direct effects of a priced managed lane project on roadway travel demand from its indirect effects. In a case study analysis, the I-580 managed project lane is predicted to directly increase VMT and CO2 emissions through induced travel demand. However, reinvestment of the lane’s revenue in regional transit is projected to reduce VMT and CO2e
emissions. In conclusion, a CRP GHG accounting should evaluate direct roadway effects and reinvestment effects separately before integrating them within a common statewide emissions accounting framework.

Icon for peer review journal article preprint

published journal article

Decarbonizing Medium- and Heavy-Duty Freight Networks: ALNS-VRP-Driven Charging Infrastructure Deployment for Zero-Emission Trucks in California

Abstract

California freight electrification depends as much on charging access and corridor planning as on vehicle adoption. Public agencies and fleets need evidence on whether depot and public charging networks can support truckload operations without increasing empty repositioning, modeled
charging-stop requirements, and route infeasibility. This study develops an operations-based freight charging assessment for mixed diesel and battery-electric truck operations and applies it to controlled California truckload scenarios. Rather than optimizing final station sites, the framework evaluates predefined depot-adjacent and public fast-charging sites through route feasibility, total and deadhead VMT, modeled charging stop rows, active charging locations, and cost-accounting indicators. The results are scenario-level route-record comparisons and do not reflect observed daily truck operations or session-level charging dwell measurements.

Icon of report

book/book chapter

Responses to Transit Homelessness

Abstract

Punitive responses restrict activities associated with homelessness through policing and can involve “hostile architecture,” such as seat dividers on bus benches. Outreach responses engage with unhoused transit riders to offer them referrals to services, shelter, and housing, often through collaboration with social service providers. These include centralised hubs of services, mobile outreach teams, transportation to shelters, and discounted fares. Proactive interventions include building shelters or housing on transit land and service planning with unhoused travellers in mind. While there are only a few evaluations of these strategies, the literature does indicate a growing awareness that removing unhoused riders from transit systems through punitive strategies addresses the challenge only momentarily, while external partnerships with social service agencies may offer more humane, effective, and sustainable solutions.

Icon of report

book/book chapter

Homelessness in Transit Settings

Abstract

Many in homelessness seek shelter on transit vehicles, at transit stations, and in transit facilities. Surveys find that homelessness is prevalent on public transport, with especially high concentrations on larger systems and at central nodes. In regions with detailed counts, cold-climate cities and those with 24/7 service have reported over 60% of their unsheltered population found on transit vehicles or stops some years. However, data on homelessness on transit is patchwork at best. Almost all US transit agencies find homelessness a challenge, exacerbated by the COVID-19 pandemic. Those who shelter on transit are more likely to be homeless for at least a year and more structurally disadvantaged than their unhoused peers elsewhere. People experiencing homelessness do not just use transit for shelter: transit is the mode most commonly reported among studies of how unhoused people travel. Transit operators are increasingly recognizing that serving the unhoused population is part of their responsibility.

Icon of report

book/book chapter

Transit Ambassadors

Abstract

A number of U.S. (public transport agencies (particularly rail systems) launched transit ambassador programmes in the 2010s and 2020s. Unarmed transit ambassadors serve as “eyes and ears” on transit vehicles and at stations. They help riders with customer service tasks, report incidents to other, more specialised staff, and broadly serve as figures of authority and vigilance where needed. Ambassadors orient riders; offer ticketing help; greet passengers and answer questions; and report crime, uncleanliness, and broken equipment. In emergency circumstances, ambassadors may render medical aid and respond to overdoses. They de-escalate altercations and serve as a first point of contact to people in homelessness. In the U.S., the nationwide racial reckoning after the 2020 murder of George Floyd by police prompted transit agencies to start or expand their civilian ambassador programmes. Very little research has studied transit ambassador programmes or evaluated their effectiveness.

Icon for misc.

website

StoryMap: Hiding Prejudice behind Parking

Publication Date

September 28, 2026

Author(s)

Abstract

Building a mosque requires careful planning to comply with zoning laws and manage community sentiment. Consider the Islamic Society of Santa Barbara (ISSB), the first mosque in this coastal California region. It took ISSB nearly 19 years to open after they purchased property in a rural part of the county. Why 19 years? A combination of city planning obstacles created the delay. First, the establishment of the town of Goleta in 2002 required ISSB to pull its original permit from Santa Barbara County and transfer it to Goleta, which, as a newly incorporated city, still lacked a functioning planning commission. Later, Goleta lost key staff members, delaying the project by three years. Most significantly, ISSB faced overwhelming opposition across 16 public hearings spanning nearly seven more years. Opponents at these hearings raised concerns about many issues, including the mosque’s design, the building’s potential impact on bird flight, and, most notably, where people who come to pray will park their cars. ISSB is not alone. According to the Institute for Social Policy and Understanding (ISPU), opposition to mosques is at an all-time high. In this context, it can be easy to focus on overt discrimination and zoning disputes. But it is just as important to show how benign and overlooked technical requirements – like parking – can become a cudgel to stop Muslim Americans from building places to gather and pray.

Icon for peer review journal article preprint

published journal article

Transportation Labor Challenges for Gig Drivers

Abstract

Given the dynamic landscape surrounding the classification of workers in California, it is important to consider how the existing legal and regulatory environment may impact app-based gig drivers, including transportation network companies (TNCs, also known as ridehailing) and courier network services (CNS). Using a multi-method approach, we conducted a literature review (n = 41 sources), expert interviews (n = 8), and case study analysis (n = 7) between October 2022 to May 2024 to better understand how California’s gig drivers are impacted by state legislation and regulation (i.e., Assembly Bill 5, Proposition 22, and Senate Bill 1014). The expert interviews found that gig drivers are concerned with fair pay, benefits, labor classification, and transparency from the app-based platforms on issues related to punitive actions (i.e., deactivations). Drivers also raised concerns about California’s Clean Miles Standard (also known as SB 1014), which requires 90 % of vehicle miles traveled be electric by 2030, due to the financial costs associated with acquiring and operating electric vehicles (EVs) and limited public charging availability. The seven case studies examine gig labor policies from other states and countries (e.g., policies that may help enhance driver working conditions, platform regulation, and facilitate the EV transition). Together, these methods explore the tension between sustaining an app-based gig driving platform and providing fair compensation and working conditions for gig drivers. The study finds that state and/or local policies establishing minimum pay for drivers and policies enhancing transparency and appeal processes for driver deactivations could help improve working conditions for gig drivers. Various state agencies, such as the California Public Utilities Commission, could support gig drivers through incentives for the purchase of EVs and installation of EV charging near their homes and driving locations.

Icon for peer review journal article preprint

published journal article

The Religion of Parking: How Land Use Planning Enables Anti-Muslim Prejudice

Publication Date

September 18, 2026

Author(s)

Abstract

In this article the research team considers a neglected injustice of parking policy: religious intolerance. Through qualitative interviews and a review of public hearing transcripts and official records, the research shows how residents and officials across the country use parking concerns to mask anti-Muslim prejudice and fight the construction of mosques. The team has isolated the role of religious discrimination quantitatively through a paired comparison of mosques and churches, finding newly proposed mosques are 16% to 18% more likely to experience opposition than newly proposed churches nearby. Further, in contrast to the mosques, parking concerns with the churches never made local news. By comparing parking ratios, the research team also demonstrates both mosques and churches typically provided more parking than codes required. These findings from the team’s mixed-methods study expand the transportation equity agenda to include religion and create space for planners to rethink how intolerance enters planning practice. Takeaway for practice: Planners should consider how zoning provisions that allow for regulatory discretion, such as parking requirements, open up avenues for prejudice. Although planners can shut down or disregard openly discriminatory comments at public hearings, it is hard for them to assess whether concerns over parking—and, by extension, other technical issues such as traffic and water—are genuine or are masks for underlying animus. Although federal laws like the Religious Land Use and Institutionalized Persons Act (RLUIPA) protect religious institutions from discrimination, mosque proponents and their attorneys are often reluctant to file lawsuits, particularly against agencies with discretionary authority, due to fear of costs and delays, or simply a desire to be friendly neighbors. Countering prejudice in land use planning therefore calls for removing procedural obstacles to development, giving city staff the authority to handle more permitting decisions ministerially, and eliminating parking requirements altogether.