published journal article
Continuous kinematic wave models of merging traffic flow
Transportation Research Part B: Methodological
Publication Date
September 1, 2010
Area of Expertise: Unspecified
working paper
Estimating Operating Costs of Fixed Guideway System Proposals
Publication Date
December 1, 1978
Author(s)
James Ortner
Working Paper
UCI-ITS-WP-78-13
Abstract
Scenario writing is presented in this paper as a technique which can assist in the evaluation of proposed system operating costs. This technique makes it possible to examine the impacts of alternative trends on operating cost escalation. Two projects proposed for Los Angeles, the Wilshire subway and the Downtown People Mover are used as case studies. The analysis of the data generated from the scenarios illustrates that the problems of operating cost escalation will continue despite incorporation of advances in transit technology. The discussion is presented as follows: First, the application of advanced technology to two recently constructed rail transit systems is reviewed. This subject is presented to demonstrate that large-scale automation does not prevent operating deficits. Second, the three major categories of people mover systems are described. Based on the experience of automated rail transit systems and people mover systems, UMTA has chosen to use the simplest people mover technology for testing in downtown environments. Third, the issue of whether planners can forecast operating cost of high capital cost transit system proposals is analyzed. The two case studies with the scenarios are then presented.
Suggested Citation
James Ortner (1978) Estimating Operating Costs of Fixed Guideway System Proposals. Working Paper UCI-ITS-WP-78-13. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/2c53k863. published journal article
A Systematic Framework to Identify Violations of Scenario-dependent Driving Rules in Autonomous Vehicle Software
Proceedings of the ACM on Measurement and Analysis of Computing Systems
Publication Date
June 4, 2021
Author(s)
Qingzhao Zhang, David Ke Hong, Ze Zhang, Qi Alfred Chen, Scott Mahlke, Z. Morley Mao
Abstract
Safety compliance is paramount to the safe deployment of autonomous vehicle (AV) technologies in real-world transportation systems. As AVs will share road infrastructures with human drivers and pedestrians, it is an important requirement for AVs to obey standard driving rules. Existing AV software testing methods, including simulation and road testing, only check fundamental safety rules such as collision avoidance and safety distance. Scenario-dependent driving rules, including crosswalk and intersection rules, are more complicated because the expected driving behavior heavily depends on the surrounding circumstances. However, a testing framework is missing for checking scenario-dependent driving rules on various AV software. In this paper, we design and implement a systematic framework AVChecker for identifying violations of scenario-dependent driving rules in AV software using formal methods. AVChecker represents both the code logic of AV software and driving rules in proposed formal specifications and leverages satisfiability modulo theory (SMT) solvers to identify driving rule violations. To improve the automation of systematic rule-based checking, AVChecker provides a powerful user interface for writing driving rule specifications and applies static code analysis to extract rule-related code logic from the AV software codebase. Evaluations on two open-source AV software platforms, Baidu Apollo and Autoware, uncover 19 true violations out of 28 real-world driving rules covering crosswalks, traffic lights, stop signs, and intersections. Seven of the violations can lead to severe risks of a collision with pedestrians or blocking traffic.
Suggested Citation
Qingzhao Zhang, David Ke Hong, Ze Zhang, Qi Alfred Chen, Scott Mahlke and Z. Morley Mao (2021) “A Systematic Framework to Identify Violations of Scenario-dependent Driving Rules in Autonomous Vehicle Software”, Proceedings of the ACM on Measurement and Analysis of Computing Systems, 5(2), pp. 15:1–15:25. Available at: 10.1145/3460082. conference paper
Real-time estimation of freeway emissions based on an inductive-loop-based surveillance system
Proceedings of the 94th annual meeting of the transportation research board
Publication Date
January 1, 2015
Author(s)
Abstract
To mitigate roadway congestion, traffic management centers monitor freeway networks and provide traffic information. Not only traffic conditions but also vehicle emissions are used to measure and evaluate air quality, its impact and operational strategies. Using reidentification (REID) information, which is an inductive-loop-detector-based advanced traffic surveillance system, this study introduces real-time speed profile estimation (SPE) methodology for estimating microscopic freeway emissions. The methodology generates individual vehicular speed profiles using a parabolic function and genetically optimized 5th-order Fourier series. Also, Next Generation SIMulation (NGSIM) US101 data were used for model calibration. Results indicate that emissions can be estimated using the proposed method with less than 4 % error. The SPE, which is real-time, cost-efficient and accurate, is a very promising freeway emissions monitoring methodology.
Suggested Citation
Jinheoun Choi, Stephen G. Ritchie and Cheol Oh (2015) “Real-time estimation of freeway emissions based on an inductive-loop-based surveillance system”, in Proceedings of the 94th annual meeting of the transportation research board, p. 15p. research report
Evaluating California’s accessory dwelling unit reforms: Preliminary evidence and lessons for state governments
Publication Date
January 1, 2023
Author(s)
Nicholas Marantz, Christopher S. Elmendorf, Youjin Kim
Suggested Citation
Nicholas J. Marantz, Christopher S. Elmendorf and Youjin B. Kim (2023) Evaluating California’s accessory dwelling unit reforms: Preliminary evidence and lessons for state governments. NYU Furman Center. Available at: https://furmancenter.org/files/Evaluating_California%E2%80%99s_Accessory_Dwelling_Unit_Reforms_508.pdf (Accessed: August 21, 2025). published journal article
Car2work: Shared mobility concept to connect commuters with workplaces
Transportation Research Record
Publication Date
January 1, 2016
Author(s)
Suggested Citation
Robert Regue, Neda Masoud and Will Recker (2016) “Car2work: Shared mobility concept to connect commuters with workplaces”, Transportation Research Record, 2542(1), pp. 102–110. Available at: 10.3141/2542-12. published journal article
Development of a dynamic cathode ejector model for solid oxide fuel cell-gas turbine hybrid systems
Journal of Fuel Cell Science and Technology
Publication Date
June 1, 2011
Author(s)
James D. Maclay, Jack Brouwer, Scott Samuelsen
Suggested Citation
James D. Maclay, Jacob Brouwer and G. Scott Samuelsen (2011) “Development of a dynamic cathode ejector model for solid oxide fuel cell-gas turbine hybrid systems”, Journal of Fuel Cell Science and Technology, 8(5). Available at: 10.1115/1.4003774. published journal article
Handbook of logistics and supply-chain management.
TRANSPORTATION RESEARCH PART A-POLICY AND PRACTICE
Publication Date
January 1, 2003
Author(s)
Suggested Citation
AC Regan (2003) “Handbook of logistics and supply-chain management.”, TRANSPORTATION RESEARCH PART A-POLICY AND PRACTICE, 37(2), pp. 189–190. Available at: 10.1016/S0965-8564(02)00040-X. conference paper
Evaluating the potential to predict activity types from GPS and GIS data
Proceedings of the 86th annual meeting of the transportation research board
Publication Date
January 1, 2007
Author(s)
Abstract
Current travel forecasting models have had limited sensitivity to policy decisions. One of the primary challenges is limitations in the primary data source, the daily travel diary (e.g., accuracy and sample size). The daily travel diary has known problems with underreporting, time inaccuracies, respondent fatigue, and other human errors. The Global Positioning System (GPS) has been recently used to supplement the daily travel diary. As GPS becomes more accurate, reliable, and cost effective, could it entirely replace the daily travel diary? GPS devices can be used to record times and locations of each activity and the trips in between. To use GPS data to replace the daily travel diary one needs to predict the activity types. The goal of this research is to test the feasibility of a model that predicts activity types based solely on: (1) GPS data from devices placed on the individualâ??s vehicle or person, (2) Land use data, such as location type, expressed as GIS data, and (3) Individual and household demographic data. This report summarizes models developed with surrogate geo-coded data using discriminant analysis and classification/ regression trees. The models predicted in which of 26 different activity types the individual participated. Accuracy for the best model was: (1) 63% for out of home activities (2) 79% when including the â??at homeâ?? activity (3) 72% considering that GPS data may miss as much as 10% of trips Since travel diaries have known underreporting problems as high as 30%, GPS data with the model developed seems competitive.
Suggested Citation
Patrick Tracy McGowen and Michael G. McNally (2007) “Evaluating the potential to predict activity types from GPS and GIS data”, in Proceedings of the 86th annual meeting of the transportation research board, p. 22p. conference paper
System performance and controller design of the PI-ALINEA ramp metering scheme
Proceedings of the 95th annual meeting of the transportation research board
Publication Date
January 1, 2016
Author(s)
Abstract
Ramp metering (RM) has been deployed for decades and it is considered an efficient technique to control lane-drop bottlenecks by limiting ramp demand and avoiding the so-called capacity-drop phenomena, drop in the downstream flux that occurs when queues form up- stream of bottleneck. In this study, the authors use a simple link queue model to describe traffic dynamics inside a merge zone with an ordinary differential equation, which combines a capacity drop model and a proportional-integral feedback control algorithm (PI-ALINEA). This enables us to analytically study the system performance and controller design for the ramp metering problem. First they analyze the systemâ??s equilibrium states, their stability, and transition subject to varying demand levels. They consider impacts of both fixed and dynamical metering rates on the equilibrium states of the system and examine the reachability of the system. They further analyze the closed-loop systems and design parameters of PI-ALINEA such that the system can be stabilized at the optimal state at a high demand level. With numerical examples they verify the analytical results with respect to the systemâ??s stability and robustness.