published journal article
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published journal article
An exploratory analysis of alternative travel behaviors of ride-hailing users
Transportation
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Associated Project
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Areas of Expertise
Abstract
The emergence of ride-hailing, technology-enabled on-demand services such as Uber and Lyft, has arguably impacted the daily travel behavior of users. This study analyzes the travel behavior of ride-hailing users first from conventional person- and trip-based perspectives and then from an activity-based approach that uses tours and activity patterns as basic units of analysis. While tours by definition are more easily identified and classified, daily patterns theoretically better represent overall travel behavior but are simultaneously more difficult to explain. We thus consider basic descriptive analyses for tours and a more elaborate approach, Latent Class Analysis, to describe pattern behavior. The empirical results for tours using data from the 2017 National Household Travel Survey show that 76% of ride-hailing tours can be represented by five dominant tour types with non-work tours being the most frequent. The Latent Class model suggests that the ride-hailing users can be divided into four distinct classes, each with a representative activity-travel pattern defining ride-hailing usage. Class 1 was composed of younger, employed people who used ride-hailing to commute to work. Single, older individuals comprised Class 2 and used ride-hailing for midday maintenance activities. Class 3 represented younger, employed individuals who used ride-hailing for discretionary purposes in the evening. Last, Class 4 members used ride-hailing for mode change purposes. Since each identified class has different activity-travel patterns, they will show different responses to policy directives. The results can assist ride-hailing operators in addressing evolving travel needs as users respond to various policy constraints.
Suggested Citation
Rezwana Rafiq and Michael G. McNally (2023) “An exploratory analysis of alternative travel behaviors of ride-hailing users”, Transportation, 50(2), pp. 571–605. Available at: 10.1007/s11116-021-10254-9.working paper
Clean or a Day: Troubles with California's Smog Check
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Associated Project
Author(s)
Working Paper
Areas of Expertise
Abstract
We have carefully reviewed “Evaluation of the California Smog Check Program and Recommendations for Program Improvements: Fourth Report to the Legislature.” Overall, we find it a thorough and competent presentation of the basic facts, though we disagree with the conclusions. Our major concern is one of perspective. It appears that the authors of the report are simply too close to the issue, too enmeshed in the details of implementation. We think it worthwhile to step back from the technical issues to take an overall view of the inspection and maintenance (I/M) program for reducing auto emissions.
Suggested Citation
Amihai Glazer, Daniel Klein and Charles Lave (1993) Clean or a Day: Troubles with California's Smog Check. Working Paper UCI-ITS-WP-93-6, UCTC 163. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/8vm1s03r.research report
Prototype design and evaluation of hybrid solid oxide fuel cell gas turbine systems for use in locomotives
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Author(s)
Abstract
Hybrid solid oxide fuel cell-gas turbine (SOFC-GT) systems are among the most efficient and lowest emitting power generation systems conceived for use in locomotives. Their superiority was proven in stationary power applications with near-zero (natural gas operation) to zero (hydrogen operation) pollutant emissions. However, the feasibility and dynamic operation of these systems for use in locomotives has not been extensively investigated. In this report, a new system based on existing National Fuel Cell Research Center (NFCRC) control methods was developed by NFCRC at the University of California, Irvine (UCI) for these types of systems. These control strategies enable the hybrid SOFC-GT system for locomotive engines to follow dynamic power demands while keeping all of the components and system operating variables within acceptable limits of performance under fuel utilizations between 75 and 80 percent. A detailed economic analysis of potential SOFC-GT locomotive production and operation costs in comparison to other low pollutant emitting alternatives (e.g., diesel-electric, battery electric, catenary-electric) was accomplished. The economic analyses show that SOFC-GT systems are likely to cost more and lead to higher costs for delivering goods per ton-mile than the diesel-electric alternative which has higher emissions. SOFC-GT locomotives are likely to produce lower operating costs compared to the catenary-electric alternative, and significantly lower operating costs compared to the battery-electric alternative.
Suggested Citation
Ali Azizi, Philipp Ahrend, G. Scott Samuelsen and Jack Brouwer (2019) Prototype design and evaluation of hybrid solid oxide fuel cell gas turbine systems for use in locomotives, p. 124p.published journal article
A Numerical Solution of Three-Dimensional Problems in Dynamic Elasticity
Journal of Applied Mechanics
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Author(s)
Abstract
The equations governing the dynamic deformation of an elastic solid are considered as a symmetric hyperbolic system of linear first-order partial-differential equations. The characteristic properties of the system are determined and a numerical method for obtaining the solution of mixed initial and boundary-value problems in elastodynamics is presented. The method, based on approximate integral relations along bicharacteristics, is an extension of the method proposed by Clifton for plane problems in dynamic elasticity and provides a system of difference equations, with second-order accuracy, for the explicit determination of the solution. Application of the method to a problem which has a known solution provides numerical evidence of the convergence and stability of the method.
Suggested Citation
W. W. Recker (1970) “A Numerical Solution of Three-Dimensional Problems in Dynamic Elasticity”, Journal of Applied Mechanics, 37(1), pp. 116–122. Available at: 10.1115/1.3408418.working paper
Objective and Subjective Dimensions of Travel Impedance as Determinants of Commuting Stress
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Author(s)
Abstract
The stressful characteristics of commuting constraints are conceptualized in terms of both physical and perceptual conditions of travel impedance. This study develops and operationalizes the concept of subjective impedance, as a complement to our previously developed concept of impedance as a physically defined condition of commuting stress. The stress impacts of high impedance commuting were examined in a study of 79 employees of two companies in the follow-up testing of a longitudinal study. Subjective impedance was found to be overlapping but not isomorphic with physical impedance, and these two dimensions were found to have differential relationships with health and well being outcomes. The physical impedance construct received further confirmation in validational analyses and in predicted effects on various illness measures and job satisfaction. The newly constructed subjective impedance index was significantly related to evening home mood, residential satisfaction, and chest pain. Job change also was found to be influenced primarily by commuting satisfaction. The results are discussed within an ecological framework emphasizing inter-domain transfer effects and situational moderators of commuting stress.
Suggested Citation
Raymond W. Novaco, Daniel Stokols and Louis Milanesi (1989) Objective and Subjective Dimensions of Travel Impedance as Determinants of Commuting Stress. Working Paper UCI-ITS-WP-89-4. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/8xr9q9gt.conference paper
Cvo perspectives on the usefulness of various sources of traffic information
Proceedings of the 80th annual meeting of the transportation research board
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Author(s)
Abstract
The objective of this research is to understand how trucking companies perceive the benefits of traditional and advanced traveler information sources. There is considerable interest in identifying the appropriate public sector role for investments in real-time traveler information sources. Managers in charge of the California operations of more than 1,100 private and for-hire trucking companies were asked to evaluate the usefulness of various sources of traffic information. These evaluations were collected on ordinal scales, and nonlinear canonical correlations analysis models were computed to simultaneously link company characteristics and perceptions of the value of information sources for dispatchers and for drivers. In addition, perceptions of the benefits of a set of improved sources of accurate, up-to-the- minute traffic information were examined. The results show how segments of the trucking industry value different sources of traffic information
Suggested Citation
Thomas F. Golob and Amelia C. Regan (2001) “Cvo perspectives on the usefulness of various sources of traffic information”, in Proceedings of the 80th annual meeting of the transportation research board, p. 30 p..book/book chapter
Using social science to reduce violent offending
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Author(s)
Suggested Citation
J.A. Dvoskin, J.L. Skeem, R.W. Novaco and K.S. Douglas (2011) Using social science to reduce violent offending. Oxford University Press. Available at: https://doi.org/10.1093/acprof:oso/9780195384642.001.0001.policy brief
Leveraging Robotaxis to Support Transit Riders in Emergencies
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Suggested Citation
Arash Ghaffar, Jiangbo (Gabe) Yu and Michael F. Hyland (2025) Leveraging Robotaxis to Support Transit Riders in Emergencies. Policy Brief. Available at: https://escholarship.org/uc/item/7fc5750v (Accessed: September 16, 2025).research report