published journal article

Parsing density changes: An outcome-oriented growth management policy analysis

J Hous and the Built Environ

Publication Date

November 1, 2012

Author(s)

Jae Hong Kim, Brian Deal, Arnab Chakraborty

Abstract

Although a considerable number of studies have examined the effectiveness of growth management programs in curbing sprawl and increasing aggregate densities, less attention has been paid to understanding how these noted density improvements are realized. In this paper, we assess the mechanisms that underlie changes in aggregate population densities and empirically examine detailed density changes under various growth management regimes in the US. Our county-level statistical analysis using recent US Census products and land use change data sets, finds that: (a) states with proactive growth management programs do tend to experience relative density gains, but not in jurisdictions with restrictive local land use regulations and (b) the marginal density gains appear to be attributable in large part to smaller housing vacancy rates and housing price escalations. Not surprisingly, our findings suggest that local structures are critical for achieving desired outcomes. Given the critical role of local action, the realization of compact development requires a tightly woven and integrated policy that not only makes logical sense at state levels, but can be followed and implemented at the local level.

Suggested Citation
Jae Hong Kim, Brian Deal and Arnab Chakraborty (2012) “Parsing density changes: An outcome-oriented growth management policy analysis”, J Hous and the Built Environ, 28(3), pp. 529–546. Available at: 10.1007/s10901-012-9327-0.

published journal article

Bayesian mixture model for estimating freeway travel time distributions from small probe samples from multiple days

Transportation Research Record

Abstract

This study formulates a hierarchical Bayesian mixture model for estimating travel time distributions along freeway sections by using small data samples from vehicle probes, which have been collected over multiple days. Two normal components are used to capture the heterogeneity in the experienced travel times and to model various distributional shapes generally known to be skewed or multimodal. Travel time data collected during different intervals under similar traffic conditions are used to construct the prior for model parameters via a hierarchical Bayesian formulation. The posterior distributions can be continuously updated as new data from probes become available, and are used for prediction under different levels of data availability. A simulation study shows that true travel time distribution for each section during each interval can be well-approximated with the use of this proposed model.

Suggested Citation
Klayut Jintanakul, Lianyu Chu and R. Jayakrishnan (2009) “Bayesian mixture model for estimating freeway travel time distributions from small probe samples from multiple days”, Transportation Research Record, 2136(1), pp. 37–44. Available at: 10.3141/2136-05.

conference paper

Private Autonomous Vehicles and Their Impacts on Last-mile Travel: Integrated Mode Choice and Parking Assignment Model

101st Annual Meeting of the Transportation Research Board

Publication Date

January 1, 2022
Suggested Citation
Younghun Bahk, Michael Hyland and Sunghi An (2022) “Private Autonomous Vehicles and Their Impacts on Last-mile Travel: Integrated Mode Choice and Parking Assignment Model”. 101st Annual Meeting of the Transportation Research Board.

conference paper

Evaluating the impacts of start-up and clearance behaviors in a signalized network: A network fundamental diagram approach

Proceedings of the 98th annual meeting of the transportation research board

Publication Date

January 1, 2019

Abstract

Numerical simulations have shown that the network fundamental diagram (NFD) of a signalized network is significantly affected by the green ratio, and an analytical approximation of the NFD has been derived from the link transmission model.However, the consistency between these approaches has not been established, and the impacts of other factors are still unrevealed. In this paper, the authors evaluate the impacts of start-up and clearance behaviors in a signalized network from a network fundamental diagram approach. Microscopic simulations based on Newellâ??s car-following model are used for testing the bounded acceleration (start-up) and aggressiveness (clearance) effects on the shape of the NFD in a signalized ring road.This new approach is shown to be consistent with theoretical results from the link transmission model, when the acceleration is unbounded and vehicles have the most aggressive clearance behaviors. This consistency validates both approaches; but the link transmission model cannot be easily extended to incorporate more realistic start-up or clearance behaviors. With the new approach, the authors demonstrate that both bounded acceleration and different aggressiveness lead to distinct network capacities and fundamental diagrams. In particular, they lead to start-up and clearance lost times of several seconds; and these lost times are additive. Therefore, the important role that these behaviors play in the NFD shape is studied to reach a better understanding of how the NFD responds to changes. This will help the authors to design better start-up and clearance behaviors for connected and autonomous vehicles

Suggested Citation
Adria Morales Fresquet and Wenlong Jin (2019) “Evaluating the impacts of start-up and clearance behaviors in a signalized network: A network fundamental diagram approach”, in Proceedings of the 98th annual meeting of the transportation research board, p. 20p.

published journal article

Editorial objectives - decision-analysis

MANAGEMENT SCIENCE

Publication Date

January 1, 1995

Author(s)

Rt Clemen, Lr Keller
Suggested Citation
Rt Clemen and Lr Keller (1995) “Editorial objectives - decision-analysis”, MANAGEMENT SCIENCE, 41(5), p. U3.

research report

Energy commission models for analyzing and projecting household transportation energy demand: Evaluation, model improvement options, and recommendations

Publication Date

January 1, 2016

Author(s)

David Bunch, David Brownstone
Suggested Citation
David S. Bunch and David Brownstone (2016) Energy commission models for analyzing and projecting household transportation energy demand: Evaluation, model improvement options, and recommendations. University of California, Davis and University of California, Irvine.

research report

Microsimulation Modeling of High Occupancy Toll (HOT) Concept in HOV Lanes

Abstract

This project developed a new HOV driver behavioral model that incorporates an access preference/choice model for examining travel time savings and a traffic model for calculating the acceptable gap to get in/out of buffer-separated HOV lane facilities. The model is incorporated into the Paramics simulator as a plug-in developed through API (Application Programming Interface) programming. In order to extend its capability for calibration and implementation, several user-specified parameters were incorporated during the model development process, including ingress and egress points selection control, and provision traffic information updates. The parameters of the model were tested and evaluated using both a sample, idealized, segment of freeway as well as a simulation network of the SR-57 freeway in Orange County, California. Sensitivity analyses were performed to evaluate the reasonableness of the model; the freeway network was further investigated for model validation purposes. The results demonstrate the reasonableness of the proposed model under various traffic conditions. The proposed model also was demonstrated to better capture the weaving maneuvers observed on the SR-57 freeway.

Suggested Citation
Will Recker, Lianyu Chu and Shin-Ting Jeng (2009) Microsimulation Modeling of High Occupancy Toll (HOT) Concept in HOV Lanes. Research Report CA10-1043. ITS-Irvine. Available at: https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/f0017237-final-report-task-1043.pdf.

Phd Dissertation

Novel Vulnerability Discoveries, Measurements, and Attack Designs for Safety-Critical Autonomous Systems from Practicality Perspectives

Publication Date

January 1, 2024

Author(s)

Abstract

Autonomous systems, such as autonomous driving (AD), rely heavily on real-time perception systems to detect and interpret their surroundings, such as traffic cones, pedestrians, traffic signs, vehicles, etc. These perception systems predominantly employ Deep Neural Networks (DNNs) for tasks such as real-time object detection due to their superior performance. However, DNNs are inherently vulnerable to adversarial attacks—maliciously crafted inputs designed to cause the DNNs to malfunction. Given the safety- and mission-critical nature of autonomous systems, it is crucial to systematically investigate the potential security vulnerabilities of these systems in real-world settings. So far, one of the most general yet crucial limitations for prior research works in this area is their limited practicality in real-world autonomous system setups, either due to their sole focus on the AI component alone, which makes it non-trivial to transfer their component-only attack effects to the system level, or due to their research scopes limited to academic prototypes instead of real-world systems. For example, almost all prior adversarial attacks on Traffic Sign Recognition (TSR) systems have only assessed the effects on academic TSR models, leaving the impacts on real-world commercial TSR systems largely unexplored. While a few recent works have attempted to evaluate the impact on commercial TSR systems, these efforts are typically confined to a single vehicle model, sometimes even an unidentified one, raising questions about both the generalizability and representativeness of their findings. In this dissertation, I present a suite of research efforts toward novel vulnerability discoveries, measurements, and attack designs for safety-critical autonomous systems from practicality perspectives. By systematically discovering and understanding the security vulnerabilities at both the DNN model level and autonomous system level, these research efforts aim to provide new and useful insights that can inspire further exploration of this largely under-explored aspect in this research area.

Suggested Citation
Ningfei Wang (2024) Novel Vulnerability Discoveries, Measurements, and Attack Designs for Safety-Critical Autonomous Systems from Practicality Perspectives. PhD Dissertation. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991035677822804701.

Preprint Journal Article

Beyond Infrastructure: Patterns of Environmental Justice and Multi-Level Governance in Greater Los Angeles Transportation and Hazard Planning

Abstract

This study evaluates how environmental justice principles are integrated into transportation and hazard plans across multiple levels of jurisdictions in Greater Los Angeles, revealing how the multi-level governance framework shapes planning practices for environmental justice integration across levels and over time. A content analysis was conducted on 16 transportation, hazard preparedness, climate action, and racial equity plans to develop a scoring methodology. Through comparison the study identified patterns and factors contributing to effective environmental justice integration in transportation and hazard planning. Findings show that although infrastructure (transportation and hazard) plans achieve higher environmental justice integration on average than other plans after 2019, some subdimensions – like recognition justice – remain less integrated. Curiously, the positive trend between environmental justice and multi-level governance observed for climate action and racial equity plans is not observed for infrastructure plans, suggesting greater nuance among the strategies that lead to its successful integration in infrastructure planning.

conference paper

A Choice Experiment Survey of Drayage Fleet Operator Preferences for Zero-Emission Trucks

Proceedings, 104th Annual Meeting of the Transportation Research Board

Abstract

Many U.S. states are supporting the transition of the heavy-duty vehicle (HDV) sector to zero-emission vehicles (ZEVs), with California leading the way through its policy and regulatory initiatives. Within various HDV fleet segments, California’s drayage fleets face stringent targets, requiring all vehicles newly registered in the Truck Regulation Upload, Compliance, and Reporting System to be ZEVs starting January 2024, and all drayage trucks in operation to be zero-emission by 2035. Understanding fleet operator behavior and perspectives is crucial for achieving these goals; however, it remains a critical knowledge gap. This study investigates the preferences and influencing factors for ZEVs among drayage fleet operators in California. We conducted a stated preference choice experiment survey, developed based on previous qualitative studies and literature reviews. With participation from 71 fleets of various sizes and alternative fuel adoption status, we collected 648 choice observations in a dual response design, consisting of a forced choice between ZEVs and a free choice between ZEVs and status quo alternatives. Multinomial logit model analyses revealed driving range and purchase costs as significant factors for ZEV adoption, with charging facility construction costs also critical in hypothetical choices between ZEVs and status quo alternatives. Fleet or organization size also influenced ZEV choices, with large fleets more sensitive to operating costs and small organizations more sensitive to off-site stations. These findings enhance our understanding in this area and provide valuable insights for policymakers dedicated to facilitating the transition of the HDV sector to zero-emission.

Suggested Citation
Youngeun Bae, Stephen Ritchie and Craig R Rindt (2025) “A Choice Experiment Survey of Drayage Fleet Operator Preferences for Zero-Emission Trucks”, in Proceedings, 104th Annual Meeting of the Transportation Research Board. Washington, D.C..