MS Thesis

Generation of realistic hypothetical urban network configurations for simulated studies of future mobility options

Publication Date

January 1, 2021

Author(s)

Negin Shariat

View MS Thesis

Abstract

ABSTRACT OF THE THESISGeneration of realistic hypothetical urban network configurations for simulated studies of future mobility optionsByNegin ShariatMaster of Science in Civil and Environmental EngineeringUniversity of California, Irvine, 2021Professor R(Jay) Jayakrishnan, ChairTraditional network generators are typically used for pure network studies within idealized optimization or modeling contexts in fields such as Operations Research and Computer Science. But for rare exceptions, such schemes for generating hypothetical networks have not been used in transportation studies and research. This is despite the recognition in many studies that the results in each study were not generalizable or transferable due the study being on limited networks that are often idealized forms of real networks. Newer mobility paradigms envisaged in the near future also make it important to now develop generators of data on hypothetical future network geometries and layouts, as well as the associated supply and demand. The reason for not using network generators in transportation studies is the myriad complexities that need to be addressed in the urban network context. This study describes a network generation framework that focuses on several such complexities (i.e. parameters and their interrelationships) with respect to network form, node density, link connections, freeway link generation, ramp generation, etc. The proposed framework generates not only different sizes and topologies but also more detailed data usable in agent-based models like activity locations. This framework also highlights the demand-side information needed in these models and generates randomly distributed agent trips with defined activities so that they are also usable in activity-based models. Illustrative results are provided for a few candidate networks generated by the proposed network generation methodology and the study discusses several associated details of conceptual and practical significance. Finally, a simple method is suggested for generating transit network (nodes and links) within the base network, and a method for improving it is also discussed.

Suggested Citation

Negin Shariat (2021) Generation of realistic hypothetical urban network configurations for simulated studies of future mobility options. MS Thesis. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/u4evf/cdi_cdl_escholarship_oai_escholarship_org_ark_13030_qt4068821p.

MS Thesis

Calibration and Validation of Generalized Bathtub Model with Boston’s Bluebikes Data

Publication Date

January 1, 2021

Author(s)

Joseph Lo

View MS Thesis

Abstract

Most existing traffic flow models rely on data collection methods that require a detailed layout of networks with compilations of recorded individual trip data. Although these procedures have been reliable, they also possess disadvantages such as high computation costs and a lack of privacy protection. Thus, in search of a lower cost alternative that can also effectively protect consumer privacy, we analyzed the Bathtub traffic flow model as a potentially viable data collection protocol.To test whether concepts can be proven, conservation equations can be consistent, and outputs can be obtained with accuracy through the Bathtub model, I performed model calibration and validation on data provided by Bluebikes, Metro Boston’s public bike share program. The following components were tested: unified relative space paradigm, conservation equations, and Bathtub model. These components were tested through the following steps: data organization, definition of steps, Bathtub model selection, Bathtub variables, Bathtub relative variables, average speed, conservation equation validation, and model solution. The unified relative space paradigm unified the network trips using remaining trip distances. Bluebikes trip distance distribution showed a log-normal distribution, which failed to meet the negative exponential and time-independent trip distance distribution assumption. The conservation in total trips equation was validated with perfect accuracy, while the conservation in trip-miles-traveled equation was validated with good accuracy. The generalized Bathtub model solution also produced accurate results, where space-mean speed yielded the best results. Given the model’s novelty and potential for privacy-preservation and application, there are many possibilities for future study, such as: data collection protocols with the Bathtub model, compatibility with other transportation modes, and comparisons with reality. This study establishes the preliminary step in putting theory to practice, as we aim towards application.

Suggested Citation

Joseph Hiu-Fung Lo (2021) Calibration and Validation of Generalized Bathtub Model with Boston’s Bluebikes Data. MS Thesis. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/u4evf/cdi_cdl_escholarship_oai_escholarship_org_ark_13030_qt4m07g364.

published journal article

Rail transit ridership changes in COVID-19: Lessons for station area planning in California

Journal of Urban Mobility

Publication Date

December 1, 2025

Associated Project

Rail Transit Ridership in California: Lessons Learned from Station Area Assessments

Author(s)

Jing Li, Daniel A. Rodriguez, Susie Pike, Michael McNally

Areas of Expertise

Public Transit, Shared Mobility, & Active Transportation Travel Behavior, Land Use, & the Built Environment

View published journal article

Abstract

Emerging evidence suggests that the recovery of transit ridership post-COVID has been uneven, especially for rail transit. This study aims to understand the station area land use, built form, and transit network characteristics that explain station-level changes in transit ridership pre- and post-COVID, and explores the degree to which those changes are rail transit-specific or the result of overall changes in visits to station areas. Specifically, the study examines ridership changes between 2019 and 2021 for 242 rail stations belonging to the Bay Area Rapid Transit (BART), San Diego Metropolitan Transit System (MTS), Sacramento Regional Transit (SACRT), and LA Metro and associate those changes with the built environment, socio-demographics, and rail network characteristics around each station using regression analysis. The study also compares these changes in ridership to overall changes in activity aggregated by station area type. The study found there was an overall decrease in station-level ridership of 72 %, but changes were not uniform, with 92 stations decreasing more and 152 stations decreasing less. The study also found that ridership declined more drastically than overall station area activity across all four rail systems, which implies that rail transit riders were more sensitive to pandemic-related changes than other commuters. The findings suggest that a rail transit ridership recovery strategy should strategize to reinvent and reinforce downtowns as destinations, and shift rail transit services to appeal to non-commute travel, as well as enhance bike and pedestrian accessibility around stations.

Suggested Citation

Li, M., Rodriguez, D.A., Pike, S. and McNally, M.. (2025), “Rail transit ridership changes in COVID-19: Lessons for station area planning in California”, Journal of Urban Mobility, Vol. 8, p. 100153.

Related Publications

research report | Sep 2024

Rail Transit Ridership Changes in COVID-19: Lessons from Station Area Characteristics

policy brief | Sep 2024

Decline of Rail Transit Requires New Strategies

MS Thesis

A Spatial Analysis of Vehicle Dismantling in California

Publication Date

January 1, 2025

Author(s)

Llorenc Miquel I Solé

View MS Thesis

Abstract

Vehicle dismantling facilities play a critical role in recycling metals from end-of-life vehicles (ELVs). However, these facilities can impose environmental burdens on nearby communities, including noise, air pollution, and groundwater contamination, especially when operations do not comply with legal standards. While the siting of hazardous facilities has been widely studied through an environmental justice (EJ) lens, vehicle dismantlers have received limited attention. This study examines these patterns in California, highlighting their unique characteristics and implications for social and environmental equity. Using a Heteroskedastic Binary Logit model to capture local differences, this thesis shows that vehicle dismantlers are more likely to be located in census tracts with higher levels of social disadvantage, although not disproportionately in low-income areas. Composite variables, such as the CalEnviroScreen score and components of the Social Vulnerability Index, are important for predicting the presence of dismantlers, linking these facilities to broader patterns of environmental and social vulnerability. While results do not explicitly find racial disparities, findings suggest that vehicle dismantlers are concentrated in highly polluted areas, which are often disproportionately inhabited by disadvantaged populations, which raises environmental injustice concerns. Conversely, population density is also a significant factor, which is inversely correlated with the presence of vehicle dismantlers. These facilities often require substantial land, which is expensive in densely populated urban areas. A better understanding of the factors influencing the siting of these facilities is useful to craft better policies to address social and environmental injustices, promote sustainability and enhance social equity.

Suggested Citation

Llorenç Miquel i Solé (2025) A Spatial Analysis of Vehicle Dismantling in California. MS Thesis. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991035687099404701.

published journal article

Arterial bus lane warrants

Australian Road Research

Publication Date

January 1, 1978

Author(s)

Stephen Ritchie

Suggested Citation

S.G. Ritchie (1978) “Arterial bus lane warrants”, Australian Road Research, 8(4), pp. 63–67.

published journal article

Just Look at the Map: Bounding Environmental Review of Housing Development in California

Environmental Law

Publication Date

January 1, 2024

Author(s)

Eric Biber, Christopher Elmendorf, Nicholas Marantz, Moira O'Neill

View published journal article

Suggested Citation

Eric Biber, Christopher Elmendorf, Nicholas Marantz and Moira O'Neill (2024) “Just Look at the Map: Bounding Environmental Review of Housing Development in California”, Environmental Law, 54, p. 221. Available at: https://heinonline.org/HOL/Page?handle=hein.journals/envlnw54&id=237&div=&collection=.

published journal article

Microsimulation of flexible transit system designs in realistic urban networks

Transportation Research Record

Publication Date

January 1, 2005

Author(s)

Cristian Cortes, Laia Pages, R. (Jay) Jayakrishnan

View published journal article

Suggested Citation

Cristián E. Cortés, Laia Pagès and R. Jayakrishnan (2005) “Microsimulation of flexible transit system designs in realistic urban networks”, Transportation Research Record, 1923(1), pp. 153–163. Available at: 10.1177/0361198105192300117.

conference paper

An approximate least-square Monte-Carlo algorithm for solving the multi-period continuous network design problem

Proceedings of the 97th annual meeting of the transportation research board

Publication Date

January 1, 2018

Author(s)

Ke Wang, Jean-Daniel Saphores

Abstract

This paper proposes a new algorithm to solve the Multi-period Continuous Network Design Problem (MPCNDP) in a real options framework. The MPCNDP aims to find the long-term optimal highway expansion plan for a road network with stochastic demand. Analytical methods, finite difference methods or Least Square Monte Carlo simulation (LSMC) are not applicable for solving the MPCNDP because of the high dimension of the stochastic demand variables and the complexity of the intrinsic complexity of the network design problem. The authors propose an algorithm, which they call â??Approximate Least Square Monte Carlo simulationâ?? (ALSMC). This algorithm applies least square regression to estimate the value of the termination payoff function without knowing the optimal capacity improvement plan. During each iteration, only a multi-period CNDP with deterministic demand needs to be solved, which dramatically reduces the computing time of each termination payoff function. The authors first test the ALSMC method on a simple example for which the exact solution is known, and show that it converges quickly to the solution. They then test the ALSMC method on a small network with 6 centroids and 16 links, which has been used as a benchmark in dozens of papers. The authors find that the ALSMC method gives quick and reasonably accurate estimates of the termination payoff function.

Suggested Citation

Ke Wang and Jean-Daniel M. Saphores (2018) “An approximate least-square Monte-Carlo algorithm for solving the multi-period continuous network design problem”, in Proceedings of the 97th annual meeting of the transportation research board, p. 18p.

published journal article

The process of information propagation in a traffic stream with a general vehicle headway: A revisit

Transportation Research Part C: Emerging Technologies

Publication Date

June 1, 2010

Author(s)

Xiubin Wang, Teresa M. Adams, Wenlong Jin, Qiang Meng

View published journal article

Suggested Citation

Bruce (Xiubin) Wang, Teresa M. Adams, Wenlong Jin and Qiang Meng (2010) “The process of information propagation in a traffic stream with a general vehicle headway: A revisit”, Transportation Research Part C: Emerging Technologies, 18(3), pp. 367–375. Available at: 10.1016/j.trc.2009.05.011.

research report

Role of Vehicle Technology on Use: Joint analysis of the choice of Plug-in Electric Vehicle ownership and miles traveled

Publication Date

September 1, 2023

Author(s)

Debapriya Chakraborty, David Bunch, David Brownstone

View research report

Abstract

The increasing diversity of vehicle type holdings and growing demand for BEVs and PHEVs have serious policy implications for travel demand and air pollution. Consequently, it is important to accurately predict or estimate the preference for vehicle holdings of households as well as the vehicle miles traveled by vehicle body- and fuel-type to project future VMT changes and mobile source emission levels. Leveraging the 2019 California Vehicle Survey data, this report presents the application of a utility-based model for multiple discreteness that combines multiple vehicle types with usage in an integrated model, specifically the MDCEV model. The model results suggest the important effects of household demographics, residence location, and built environment factors on vehicle body type and powertrain choice and usage. Further the predictions associated with changes inbuilt environment factors like population density can inform the design of land-use and transportation policies to influence household vehicle holdings and usage that can in turn impact travel demand and air quality issues in California.View the NCST Project Webpage

Suggested Citation

Debapriya Chakraborty, David S. Bunch and David Brownstone (2023) Role of Vehicle Technology on Use: Joint analysis of the choice of Plug-in Electric Vehicle ownership and miles traveled. Final Report NCST-UCD-RR-23-30. Available at: https://escholarship.org/uc/item/3jj3v7pw (Accessed: October 11, 2023).