published journal article

Development and performance evaluation of an ITS-Ready microscopic traffic model for irvine, California

Intelligent Transportation Systems Journal

Publication Date

January 1, 2002

Abstract

The research in this paper presents the detailed development and on-line evaluation of a microscopic traffic flow model for the city of Irvine in Southern California. This effort is the first stage of evaluating micro-simulators in terms of their ability to model and analyze Intelligent Transportation Systems (ITS) under faster-than-real-time conditions. We utilize “Paramics,” a particularly promising ITS-capable advanced traffic flow simulator and visualization tool, as one of an array of newly emerging ITS-capable simulation tools and we apply it to the Irvine network as part of a staged effort to model the much larger Southern California network. The driver and vehicle models and parameters were developed to reflect U.K. driver and vehicle characteristics. In this effort we explain our procedure used the calibrate these parameters to reproduce local U.S. traffic behavior. We built a model of a conventional U.S. freeway/arterial network in Southern California and calibrated its parameters using on-line field data. The calibrated models are validated, both at the section and network levels, and evaluated relative to their potential application in Advanced Traffic Management and Information Systems (ATMIS). Based on obtained results, the calibrated model performed well during validation on a freeway link. On the full network, the vehicle release mechanism showed some time-lag in releasing demand onto the network. This is potentially due to stacking of vehicles in memory before adequate headways are found on the road to release the vehicles. Although the problem itself is simple, its effects on the results were notable.

Suggested Citation
B. Abdulhai, J.-B. Sheu and W.W. Recker (2002) “Development and performance evaluation of an ITS-Ready microscopic traffic model for irvine, California”, Intelligent Transportation Systems Journal, 7(1), pp. 79–102. Available at: 10.1080/10248070212013.

conference paper

Understanding commercial vehicle travel through new high-fidelity inductive sensors

Proceedings of the 86th annual meeting of the transportation research board

Publication Date

January 1, 2007

Abstract

Despite their impacts on traffic performance, infrastructure, environment and safety, the travel behavior of commercial vehicles is not well understood. This is largely due to limited data available to distinguish between various types of commercial vehicles and their travel patterns. This study presents a new vehicle inductance sensor technology that obtains both the undercarriage profile and axle configuration of each vehicle, the fusion of which provides the potential for distinguishing between commercial vehicles at a more detailed level. The commercial vehicle classification model developed in this study yielded encouraging results of 96.7% and 89.6% classification accuracy for the calibration dataset and test dataset respectively, and has the potential to serve as the basis for developing a more powerful commercial vehicle classification model which is able to provide further insight into the travel behavior and characteristics of commercial vehicles on roadways today.

Suggested Citation
Yeow Chern Andre Tok, Stephen G. Ritchie and Shin-Ting Jeng (2007) “Understanding commercial vehicle travel through new high-fidelity inductive sensors”, in Proceedings of the 86th annual meeting of the transportation research board, p. 22p.

published journal article

Long haul freight network design using shipper–carrier freight flow prediction: A California network improvement case study

Transportation Research Part E: Logistics and Transportation Review

Publication Date

July 1, 2010
Suggested Citation
Pruttipong Apivatanagul and Amelia C. Regan (2010) “Long haul freight network design using shipper–carrier freight flow prediction: A California network improvement case study”, Transportation Research Part E: Logistics and Transportation Review, 46(4), pp. 507–519. Available at: 10.1016/j.tre.2009.04.004.

published journal article

LTE receiver design and multipath analysis for navigation in urban environments

NAVIGATION

Publication Date

December 1, 2018

Author(s)

Kimia Shamaei, Zaher Kassas
Suggested Citation
Kimia Shamaei and Zaher M. Kassas (2018) “LTE receiver design and multipath analysis for navigation in urban environments”, NAVIGATION, 65(4), pp. 655–675. Available at: 10.1002/navi.272.

working paper

Can HOT Lanes Encourage Carpooling? A Case Study of Carpooling Behavior on the 91 Express Lanes

Publication Date

August 1, 1998

Author(s)

Abstract

This paper is a case study of carpooling behavior on the 91 Express Lanes. The 91 Express Lanes are the nation’s first implementation of High Occupancy/Toll (HOT) lanes where carpools with three or more passengers could use the lanes for free (at the time the data for this study was collected) and others pay a toll that varies by time of day to use the premium Express Lane. One concern over such a policy is that people won’t carpool if they can just pay for the travel time savings that they would normally obtain by carpooling and using a High Occupancy Vehicle (HOV) lane. Our survey data show that the rate of carpooling did not change much between the opening of the Express Lanes and now, there is a lot of changing between modes (increases and decreases in the number of passengers), there are a large number of people that carpool a few times a week, and that HOV-2s use both the regular lanes and the Express Lanes. We further investigate whether HOT lanes encourage carpooling by modeling carpool formation with discrete choice models. The results show that mode choice behavior in the corridor is similar to carpooling behavior in other locations and carpooling in the corridor is not discouraged.

Suggested Citation
Emily Parkany (1998) Can HOT Lanes Encourage Carpooling? A Case Study of Carpooling Behavior on the 91 Express Lanes. Working Paper UCI-ITS-WP-98-5. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/1rj5r3z0.

published journal article

Multi-stage charging and discharging of electric vehicle fleets

Transportation Research Part D: Transport and Environment

Publication Date

May 1, 2023

Author(s)

Matthew Dean, Felipe De Souza, Krishna Murthy Gurumurthy, Kara Kockelman

Abstract

Fleets of electric vehicles will likely shift electricity demand, and the effect of upstream charging emissions will come from generation sources that are dispatched in response. This study proposes a multi-stage charging and discharging problem to translate low-cost energy transactions into vehicle dispatch decisions. A day-ahead charging optimization problem minimizes electricity purchases and marginal emissions damages, with energy transactions becoming targets in an optimization-based dispatch strategy for an on-demand shared autonomous electric vehicle (SAEV) fleet. The framework was tested for Austin, Texas, using an agent-based simulator. Fleets can schedule charging to lower daily power costs (averaging 15.5% or $0.79/day/SAEV) while reducing health damages from generation-related pollution (2.8% or $0.43/day/SAEV). Fleet managers can increase profits ($8 per SAEV per day) by adopting a multi-stage charging and discharging strategy that can serve more passengers per day than price-agnostic dispatch strategies.

Suggested Citation
Matthew D. Dean, Felipe Augusto de Souza, Krishna Murthy Gurumurthy and Kara M. Kockelman (2023) “Multi-stage charging and discharging of electric vehicle fleets”, Transportation Research Part D: Transport and Environment, 118, p. 103691. Available at: 10.1016/j.trd.2023.103691.

Phd Dissertation

Human-centered computing and the future of work : lessons from mechanical turk and turkopticon, 2008-2015

Publication Date

June 30, 2015

Areas of Expertise

Abstract

Online labor markets such as Amazon Mechanical Turk (AMT), Uber, and TaskRabbit are contributing to rapid changes in the nature of work for hundreds of thousands of workers. These markets create significant new economic opportunities, but most currently treat workers as second-class citizens. Take-home pay is often low compared to similar work in traditional employment arrangements, and workers have limited means of influencing market design or management practice. This makes it hard for workers to create reliable livelihoods from the opportunities these markets present. This dissertation uses AMT, an online labor market for small information tasks, as a case through which to examine the consequences of treating workers as second-class citizens, to argue that future platform designs and management practices should treat workers as central stakeholders, and to develop theory and method for doing so. The central argument of the dissertation is that workers’ concerns should be more substantively and systematically addressed in the design and operation of online labor markets. Five messages elaborate this argument. First, in online labor markets, some workers are casual or transient, while others are professionals, providing significant and reliable value to customers and relying on income earned in the market to meet basic needs. Second, workers who rely on income earned through online labor markets should be considered first-class stakeholders, alongside customers and shareholders. Third, workers in online labor markets are rarely the narrowly self-interested profit maximizers of classical economic theory. Workers can be better understood as “situatedly rational” actors: human beings with incomplete information and finite cognitive capabilities whose actions and preferences are shaped by many factors, including rules, norms, and expectations. Fourth, online labor markets are not monolithic, perfectly competitive markets but parts of polycentric economic systems composed of complexly interlinked action situations characterized by imperfect competition and incomplete information. Fifth, institutions supporting crowd work research should develop an interdisciplinary practice-oriented agenda to understand the consequences of current online labor market designs and practices, and to develop new designs and practices that incorporate workers who rely on market income as central stakeholders.

Suggested Citation
MICHAEL SILBERMAN (2015) Human-centered computing and the future of work : lessons from mechanical turk and turkopticon, 2008-2015. PhD Dissertation. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/17uq3m8/alma991017757829704701.

Phd Dissertation

Network surveillance supported object-based and task-based time-bounded fault tolerance schemes and their incorporation into a timeliness-guaranteed kernel

Abstract

Real-time fault tolerance (RTFT) is a core technology for increasing the reliability of computer-based safety-critical applications such as space applications, factory automation systems, etc. In recent years, the real-time computing market has started showing explosive growth. In order to realize highly robust real-time fault tolerant computing stations, several component techniques are necessary. Among the most significant include (a) a scaleable RTFT scheme, (b) a network surveillance (NS) scheme, (c) a timeliness-guaranteed kernel that supports both the RTFT and the NS schemes. This dissertation attempts to make a significant step forward towards the goal of realizing ultra-reliable computer-based safety-critical systems. As a first step in this direction, the following new technologies have been devised: (i) the primary-shadow time-triggered message-triggered object (TMO) replication (PSTR) scheme which provides time-bounded recovery from faults in TMO structured systems, (ii) the supervisor-based network surveillance (SNS) scheme which is effective in a variety of point-to-point networks and is amenable to fault detection latency bound analysis. Second, it was observed that even though a few promising component technologies that addressed certain specific requirements of real-time fault tolerant computing stations have been established, little efforts were made to integrate these technologies. Only such integrated technologies can meet the diverse demands that are imposed by safety-critical applications. This dissertation attempts to establish guidelines for such integration. The following integrated schemes have been devised: (i) the PSTR scheme and the SNS scheme, (ii) the distributed recovery block (DRB) scheme established earlier and the SNS scheme, (iii) the adaptable DRB scheme established earlier and the SNS scheme. Third, convincing demonstrations of the validity and potential utility of the devised schemes would facilitate their use in real-world applications. A timeliness-guaranteed kernel developed earlier was extended to support all the devised schemes. A TMO-structured defense application supported by the newly extended kernel was also made fault-tolerant. Finally, the performance analyses of the RTFT and NS schemes, even though of great importance, have been scarcely practiced. We have analyzed the performance of the devised schemes and obtained some tight time bounds. The modeling and analysis techniques presented would serve as useful guides to system engineers.

Suggested Citation
Chittur Subbaraman (1997) Network surveillance supported object-based and task-based time-bounded fault tolerance schemes and their incorporation into a timeliness-guaranteed kernel. PhD Dissertation. UC Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/1go3t9q/alma991035092938504701.

policy brief

Understanding the Causes and Consequences of Local Growth Control

Abstract

In California, there has been a growing concern about rising housing cost burdens. Declining housing affordability, particularly in job-rich areas, can lead to lengthy commutes and pose significant challenges to achieving sustainable transportation and development patterns. It may also cause disproportionate impacts on vulnerable population groups by pushing members of these group to areas where jobs and other amenities are limited. Although no single factor can fully explain the rise of this critical issue, local growth control measures (e.g., growth moratoriums, density restrictions, and public facilities requirements) and other strict land use regulations have been criticized for constraining the housing supply and adding to jobs-housing imbalances. It is important to understand what motivates local growth control actions, as well as how these controls may affect land use, housing, and transportation.

Suggested Citation
Jae Hong Kim, Nene Osutei and Nicholas Marantz (2020) Understanding the Causes and Consequences of Local Growth Control. Policy Brief. UC ITS. Available at: https://doi.org/10.7922/g2ht2mmh.

working paper

Real-time Vehicle Reidentification System for Freeway Performance Measurements

Abstract

Computational resources in the traffic operation field as well as the bandwidth of field communication links, are often quite limited. Accordingly, for real-time implementation of Advanced Transportation Management and Information Systems (ATMIS) strategies, such as vehicle reidentification, there is strong interest in development of field-based techniques and models that can perform satisfactorily while minimizing computational and communication requirements in the field. The ILD (Inductive Loop Detector)-based Vehicle ReIDentification system (ILD-VReID) is an example of a currently applied approach. Although ILDs are not without limitations as a traffic sensor, they are widely used for historical reasons and the sunken investment in the large installed base makes their use in this research highly cost-effective. Therefore, this dissertation develops a new vehicle reidentification algorithm, RTREID-2, for real-time implementation by adopting a PSR (Piecewise Slope Rate) approach that extracts features from raw vehicle signature data. The results of cases studies indicate that RTREID-2 is capable of accurately providing individual vehicle tracking information and performance measurements such as travel time and speed. The potential contributions of RTREID-2 are: application to square and round single loop configurations, and reduced computational requirements because re-estimation or transferability of the speed models used in the previously developed approach is not necessary. As a consequence, RTREID-2 is free of site-specific calibration and transferability issues. A freeway corridor study also demonstrates that RTREID-2 has the potential to be implemented successfully in a congested freeway corridor, utilizing data obtained from both homogenous and heterogeneous loop detection systems. A real-time vehicle classification model, which is based on the PSR approach, was also developed on the part of RTREID-2. The classification model can successfully classify vehicles into 15 classes using single loop detector data without any explicit axle information. The initial results also suggest the potential for transferability of the vehicle classification approach and are very encouraging. To investigate real-time freeway performance measurement in a realworld setting, the design of a RTPMS (Real-time Traffic Performance Measurement System) that is based on RTREID-2 is also presented in this dissertation. A simulation of RTPMS is conducted to evaluate its feasibility. The simulation results demonstrate the potential of implementing RTPMS in real world applications.