conference paper
Development of a prototype real-time expert system for managing non-recurring freeway congestion
Proceedings of the VTT symposium (valtion teknillinen tutkimuskeskus)
Publication Date
January 1, 1990
Archives: Research Products
working paper
Performance Evaluation for Fixed Route Transit: The Key to Quick, Efficient and Inexpensive Analysis
Publication Date
December 1, 1983
Author(s)
Gordon (Pete) Fielding, Timlynn L. Babitsky, Mary E. Brenner
Working Paper
UCI-ITS-WP-83-7
Areas of Expertise
Abstract
This research uses FY 1980 Section 15 data to identify and test a set of seven key performance indicators that are useful for nationwide, fixed route, motor bus transit performance evaluation. These indicators can be used together or individually to assess transit performance, for a single system or for cross-system comparison. The second year of Section 15 data is also used to evaluate the validity of an earlier analysis based on the first year data. Rigorous cleaning, verifying and grooming procedures carried out before analysis insured that the current input data was as complete as possible. Careful decisions regarding which variables to keep and/or drop from the analysis provided the best possible set of performance indicators available in the FY 1980 Section 15 data. Use of four parallel data sets and several exploratory factor analyses detected the simple underlying structure of the data. Rigorous testing verified the structure as the most salient performance dimensions. The small subset of seven key performance indicators was identified and tested as representative of these dimensions. Results here are compared to the earlier analysis. The strength of the current research lies in both the quality of the data used and the rigor with which it was tested throughout. A strong case is made for using the seven identified performance indicators for motor bus transit performance evaluation.
Suggested Citation
Gordon J. Fielding, Timlynn L. Babitsky and Mary E. Brenner (1983) Performance Evaluation for Fixed Route Transit: The Key to Quick, Efficient and Inexpensive Analysis. Working Paper UCI-ITS-WP-83-7. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/3tr1g0n9. conference paper
Advances in modelling network dynamics incorporating behavioural considerations
Travel Behaviour research in an Evolving World, selected papers from the 12th International Conference on Travel behavior Research
Publication Date
January 1, 2012
Author(s)
Andre de Palma, R. (Jay) Jayakrishnan, Karthik C Konduri
Suggested Citation
Andre de Palma, R Jayakrishnan and Karthik C Konduri (2012) “Advances in modelling network dynamics incorporating behavioural considerations”, in R.M. Pendyala and C.R. Bhat (eds.) Travel Behaviour research in an Evolving World, selected papers from the 12th International Conference on Travel behavior Research. Lulu. com, pp. 367–372. book/book chapter
Multiple imputation methodology for missing data, non-random response, and panel attrition
Publication Date
January 1, 1998
Author(s)
Suggested Citation
David Brownstone (1998) “Multiple imputation methodology for missing data, non-random response, and panel attrition”, in Theoretical foundations of travel choice modeling. Elsevier, pp. 421–449. Available at: https://doi.org/10.1016/b978-008043062-1/50019-1. working paper
Discrete Choice Modeling for Transportation
Publication Date
January 23, 2001
Author(s)
Areas of Expertise
Abstract
This paper discusses important developments in discrete choice modeling for transportation applications. Since there have been a number of excellent recent surveys of the discrete choice literature aimed at transportation applications (see Bhat, 1997 and 2000a), this paper will concentrate on new developments and areas given less weight in recent surveys. Small and Winston (1999) give an excellent review of the transportation demand literature that includes many examples of how discrete choice models have been used in demand analysis.
research report
Life Cycle Assessment of Environmental and Economic Impacts of Deploying Alternative Urban Bus Powertrain Technologies in the South Coast Air Basin
Publication Date
June 1, 2019
Associated Project
Author(s)
Abstract
To aid in addressing issues of air quality and greenhouse gas (GHG) emissions in the South Coast Air Basin, local transit agencies are considering a shift to battery electric buses (BEBs) and hydrogen fuel cell electric buses (FCEBs). Each of these options vary in their overall effectiveness in reducing different emission types over their life cycle, associated life cycle costs, ability to meet operational needs of transit agencies, and life cycle environmental footprint. This project carried out a life cycle-based analysis and comparison of the GHG emissions, criteria pollutant emissions, and other environmental externalities associated with BEBs and FCEBs, taking into account their ability to meet operational constraints of the Orange County Transportation Authority. From an environmental footprint perspective, this study found the following. First, both FCEBs and long-range BEBs have comparable impacts for global warming potential and particulate matter formation but when the FCEBs were fueled using renewable hydrogen. Second, using electricity from the current California grid mix to drive electrolysis to produce hydrogen for FCEBs produced only marginal benefits compared to current natural-gas fueled vehicles due to the low supply chain efficiency of this pathway. Third, the mining of precious metals is a major contributor to environmental footprint categories for both BEBs and FCEBs. Fourth, both FCEVs and long-range BEBs provide significant reductions in environmental footprint compared to conventional diesel and natural gas buses. From a cost perspective, this study found the following. First, with current-day cost inputs, FCEBs and BEBs have comparable total cost of ownership, but both have slightly higher costs than diesel and natural gas buses. Second, FCEBs have an equivalent total cost of ownership to BEBs when the electricity rate for charging is $0.24/kWh. Higher values render FCEBs as the cheaper option and lower values render BEBs as the cheaper option. Second, the total cost of ownership of these technologies is highly sensitive to electricity costs, and the rapid evolution of the electricity system has strong implications for the economic comparison between BEBs and FCEBs. Overall, this study finds that while both FCEBs and BEBs provide life-cycle environmental benefits, further cost reductions in electricity rates and initial purchase costs are needed to achieve total cost of ownership parity with conventional bus powertrains. With the rapid evolution of the electricity system and falling costs for renewable electricity resources, these cost reductions may occur in the near future.
Suggested Citation
Analy Castillo, Brian Tarroja and G. Scott Samuelsen (2019) Life Cycle Assessment of Environmental and Economic Impacts of Deploying Alternative Urban Bus Powertrain Technologies in the South Coast Air Basin. Available at: https://escholarship.org/uc/item/81f4361x (Accessed: October 11, 2023).Related Publications
book/book chapter
An application of the disequilibrium adjustment framework to small area forecasting and impact analysis
Publication Date
January 1, 2012
Author(s)
Jae Hong Kim, Geoffrey J.D. Hewings
Suggested Citation
Jae Hong Kim and Geoffrey J.D. Hewings (2012) “An application of the disequilibrium adjustment framework to small area forecasting and impact analysis”, in Defining the spatial scale in modern regional analysis. Springer Berlin Heidelberg, pp. 139–155. Available at: https://doi.org/10.1007/978-3-642-31994-5_7. working paper
A Simultaneous Model of Activity Participation and Trip Chain Generation by Households
Working Paper
UCI-ITS-WP-97-11, UCI-ITS-AS-WP-97-4, UCTC 439
Areas of Expertise
Abstract
A trip generation model has been developed using a time-use perspective, in which trips are generated in conjunction with out-of-home activities, and time spent traveling is another component of overall time use. The model jointly forecasts three sets of endogenous variables – (1) activity participation and (2) travel time (together making up total out-of home time use), and (3) trip generation — as a function of household characteristics and accessibility indices. It is estimated with data from the Portland, Oregon 1994 Activity and Travel Survey. Results show that the basic model, which has ten endogenous time use and trip generation variables and thirteen exogenous variables, fits well, and all postulated relationships are upheld. Test show that the basic model, which divides activities into work and nonwork, can be extended to a three-way breakdown of subsistence, discretionary and obligatory activities. The model can also capture the effects of in-home work on trip chaining and activity participation. We use the model to explore the effects on time use and trip chaining of GIS-based and zone-based accessibility indices.
Suggested Citation
Thomas F. Golob (1997) A Simultaneous Model of Activity Participation and Trip Chain Generation by Households. Working Paper UCI-ITS-WP-97-11, UCI-ITS-AS-WP-97-4, UCTC 439. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/3ts6s6bp.Related Publications
working paper |
Jan 1999
The Determinants of Growth of Employment Subcenters
book/book chapter |
Oct 1998
Project Evaluation
working paper |
Sep 1994
Population and Employment Densities: Structure and Change
working paper |
Dec 1994
Hazard Models of Changing Household Demographics
Preprint Journal Article
Fleet Sizing for Robo-taxi Services: Comparing Novel and State-of-the-Art Scalable Modeling Approaches
Publication Date
July 19, 2022
Author(s)
Abstract
Fleet sizing is one of the most important tactical planning problems facing transportation service providers; it directly and significantly impacts costs and customer service quality. This paper proposes a network flow-based formulation to model the robo-taxi, or automated mobility-on-demand (AMOD), service fleet sizing problem. The formulation is similar to the minimum cost flow problem formulation in a time-expanded network, except it includes a set of external flows as variables to model the fleet size decision, alongside empty repositioning vehicle movements. The study compares the network flow-based approach to the state-of-the-art deterministic AMOD fleet sizing modeling approach, which formulates the problem as a path covering problem that relies on constructing shareability graphs. Both approaches make several simplifying assumptions but they both admit exact solutions to large-scale problem instances. Using New York City taxi data, this paper compares the two approaches in terms of minimum fleet size (lower bound) estimates, empty vehicle miles traveled estimates, and computational complexity and performance. We conclude that the TDTP formulation has several advantages over the path cover approach including scalability, computational efficiency, conservation of vehicles during the analysis period, and empty vehicle miles/kilometers traveled forecasts.
Suggested Citation
Arash Ghaffar, Negin Shariat and Michael Hyland (2022) “Fleet Sizing for Robo-taxi Services: Comparing Novel and State-of-the-Art Scalable Modeling Approaches”. Rochester, NY: SSRN. Available at: 10.2139/ssrn.4168352. research report
Dynamic Path-Based Equilibrium Assignment With Microscopic Traffic Simulation
Publication Date
April 1, 2005
Author(s)
Final Report
UCB-ITS-PRR-2005-13
Areas of Expertise
Abstract
This report summarizes research work conducted under TO4158 at the California ATMS Testbed of the Institute of Transportation Studies at the University of California, Irvine. Under this task order, the California ATMS testbed hosted two full-time PATH research postdocs (Henry Liu and Lianyu Chu) whose general responsibilities are focused on applications of ATMS in the Testbed environment. They are generally responsible for ensuring that the functional capabilities of the Testbed are designed, developed and maintained in a manner that complements and enhances the ATMS research objectives of the PATH program. Under the direction of PATH faculty researchers at UCI and the Testbed management team, they are generally responsible for software enhancements to the Laboratory “bench-top” system for modeling and evaluating ATMS, particularly with the microscopic simulation model Paramics. They also provided Caltrans the on-call support and technical guidance on various Caltrans micro-simulation projects related to the Paramics plugin modules developed at UCI. In addition to the general responsibilities outlined above, the PATH Researchers have specific research projects. The specific research project conducted under this task order is to develop a path-based equilibrium assignment model with micro-simulator Paramics. Since off-the-shlef Paramics can only do the link-based assignment, no path information during the traffic assignment process is stored nor provided. This will bring difficulties in the ATMS evaluation particularly related to the route diversion because partial or full path information is needed to conduct this type of evaluation with Paramics. To overcome this difficulty, a path-based assignment model is developed using Paramics Application Programming Interfaces (API) functions. The model comprises the advantages of the analytical traffic assignment model and the good properties of the simulation tools, which can represented the real world more properly. Some key techniques, route choice plug-in, turn penalty consideration and methods of successive average, and etc., were applied in the model. The Paramics V4 was selected as the demonstration simulation tool. A real grid network in Tucson, Arizona, was designed to test the performance of the model, and the results showed that the model converged to the user equilibrium as expected.