published journal article

Telecommuting and Travel during COVID-19: An Exploratory Analysis across Different Population Geographies in the U.S.A.

Transportation Research Record: Journal of the Transportation Research Board

Abstract

This study explores the impact of the COVID-19 pandemic on telecommuting (working from home) and travel during the first year of the pandemic in the U.S.A. (from March 2020 to March 2021), with a particular focus on examining the variation in impact across different U.S. geographies. We divided 50 U.S. states into several clusters based on their geographic and telecommuting characteristics. Using K-means clustering, we identified four clusters comprising 6 small urban states, 8 large urban states, 18 urban–rural mixed states, and 17 rural states. Combining data from multiple sources, we observed that nearly one-third of the U.S. workforce worked from home during the pandemic, which was six times higher than the pre-pandemic period, and that these fractions varied across the clusters. More people worked from home in urban states compared with rural states. As well as telecommuting, we examined several activity travel trends across these clusters: reduction in the number of activity visits; changes in the number of trips and vehicle-miles traveled; and mode usage. Our analysis showed there was a greater reduction in the number of workplace and nonworkplace visits in urban states compared with rural states. The number of trips in all distance categories decreased except for long-distance trips, which increased during the summer and fall of 2020. The changes in overall mode usage frequency were similar across urban and rural states with a large drop in ride-hailing and transit use. This comprehensive study can provide a better understanding of the regional variation in the impact of the pandemic on telecommuting and travel, which can facilitate informed decision-making.

Suggested Citation
Rezwana Rafiq, Michael G. McNally and Md Yusuf Sarwar Uddin (2023) “Telecommuting and Travel during COVID-19: An Exploratory Analysis across Different Population Geographies in the U.S.A.”, Transportation Research Record: Journal of the Transportation Research Board, 2677(4), pp. 562–582. Available at: 10.1177/03611981221109182.

book/book chapter

Urban and industrial environments

Publication Date

December 1, 2012

Author(s)

Joseph Dimento, Cliff Ellis

Abstract

This book presents a history of the United States freeway system especially as it relates to cities and urban planning. The roles played by transportation professionals and others, such as government officials, are explored. The impacts of changes in legislation, funding, and environmental policy are outlined. Three case studies of freeway development are included: Syracuse, New York; Los Angeles, California; and Memphis, Tennessee. Chapter topics include: America’s changing cities; The 1930s; National policy, 1939-1945; Postwar urban freeways; and Changing visions and regulations.

Suggested Citation
Joseph F.C. DiMento and Cliff Ellis (2012) Urban and industrial environments. MIT Press.

working paper

Structural Equation Modeling for Travel Behavior Research

Publication Date

November 11, 2001

Author(s)

Working Paper

UCI-ITS-WP-01-7

Areas of Expertise

Abstract

Structural equation modeling (SEM) is an extremely flexible linear-in-parameters multivariate statistical modeling technique. It has been used in modeling travel behavior and values since about 1980, and its use is rapidly accelerating, partially due to the availability of improved software. The number of published studies, now known to be more than fifty, has approximately doubled in the past three years. This review of SEM is intended to provide an introduction to the field for those who have not used the method, and a compendium of applications for those who wish to compare experiences and avoid the pitfall of reinventing previous research.

Suggested Citation
Thomas F. Golob (2001) Structural Equation Modeling for Travel Behavior Research. Working Paper UCI-ITS-WP-01-7. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/8392r1qv.

published journal article

Discrete choice with an oddball alternative

Transportation Research Part B: Methodological

Publication Date

June 1, 1995

Author(s)

Abstract

A discrete choice model is presented that explicitly recognizes differences in the error structure associated with a single `’oddball” alternative within the choice set that has properties not common to the other alternatives. The model purportedly resolves questions related to the use of alternative-specific variables in transportation choice models to capture the effects of attributes unique to a single travel alternative, such as `’schedule frequency” in the case of modal choice between personal auto and public transit. The model, which shares the general error structure of multinomial legit, is shown to be a modification of a multinomial legit subchoice by terms involving the exponential integral. The model is shown to yield different results from those produced by an equivalent multinomial legit specification. Comparisons to multinomial probit and nested legit formulations are also made.

Suggested Citation
W.W. Recker (1995) “Discrete choice with an oddball alternative”, Transportation Research Part B: Methodological, 29(3), pp. 201–211. Available at: 10.1016/0191-2615(95)00002-u.

conference paper

Evaluation and modification of constant volume sampler based procedure for plug-in hybrid electric vehicle testing

Proceedings of the SAE international powertrains, fuels and lubricants meeting, lKyoto, japan

Publication Date

January 1, 2012

Abstract

Plug-in hybrid electric vehicles (PHVs) consume both fossil fuel and grid electricity, which imposes emission testing challenges on the current constant volume sampler (CVS) test method. One reason is that in the charge-depleting cycle, PHVs having all-electric range operate the engine for a small portion of the traction energy need, causing the CVS to overdilute the exhaust gas. The other reason is that the dilution factor (DF) in the EPA calculation has an error caused by ignoring the COâ?? concentration in ambient air. This paper evaluates these challenges by testing a Toyota PHV on the industry standard CVS system combined with additional continuous sampling methodology for continuous diluents, smooth approach orifice (SAO) measurement for ambient air flow, and fuel flow meter (FFM) measurement for fuel consumption. The current EPA DF can produce an error resulting in higher mass calculation. For the test car, the error for THC is in the range 0-20% on the urban dynamometer driving schedule (UDDS), and 0-75% on the highway fuel economy test (HWFET), though it is estimated that this error amounts to less than 4.7% error for non-methane organic gas (NMOG) compared to the current SULEV emission standard. For the test car, the error for CO, NOx, and COâ?? is in the range of 0-8%, 0-3.6%, and 0-0.5%, respectively, which are negligible compared to the current SULEV emission standard. An alternative procedure is proposed for the charge depleting cycle using the continuous sampling method to ignore the time period before the engine first starts, thereby eliminating overdilution. This technique can reduce the impact of potential gas analyzer and DF error to one third compared to the current CVS method. The FFM and CVS showed matching measurements during most portions of testing and only demonstrated discrepancy of fuel consumption measurement during the first engine start cycle. The detailed reason why the FFM measured 13 grams more COâ?? than the CVS on average is likely associated with exhaust left in the vehicle tailpipe and CVS sampling line, though more investigation is needed with future testing.

Suggested Citation
Li Zhang, Tim Brown and G. Scott Samuelsen (2012) “Evaluation and modification of constant volume sampler based procedure for plug-in hybrid electric vehicle testing”, in Proceedings of the SAE international powertrains, fuels and lubricants meeting, lKyoto, japan. SAE International, pp. pp 542–559.

working paper

Economies of Scale and Self-Financing Rules with Noncompetitive Factor Markets

Publication Date

November 1, 1996

Author(s)

Working Paper

UCI-ITS-WP-96-10

Abstract

When a firm or public authority prices output at marginal cost, its profits are related to the degree of local economies of scale in its cost function. As is well known, this result extends to the case where some congestion-prone inputs are supplied by users. I show that contrary to common belief, the result holds even when scale economies are affected by a rising factor supply curve. In that case, constant returns to scale in production produces diseconomies of scale in the cost function, making marginal-cost pricing profitable. Examples are provided for a monopsonist both with and without price discrimination. In the latter case, second-best pricing is also considered: profits then are not governed in the usual way either by returns to scale in production or by scale economies in the cost function, but some useful bounds are provided.

Suggested Citation
Kenneth A. Small (1996) Economies of Scale and Self-Financing Rules with Noncompetitive Factor Markets. Working Paper UCI-ITS-WP-96-10. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/9qp0s911.

conference paper

Continuous kinematic wave models of merging traffic flow

Proceedings of 88th annual meeting of the transportation research board, washington, DC

Publication Date

January 1, 2009

Author(s)

Suggested Citation
W.-L. Jin (2009) “Continuous kinematic wave models of merging traffic flow”, in Proceedings of 88th annual meeting of the transportation research board, washington, DC.

published journal article

Estimating the electricity system benefits of scaling up E-bike usage in California

Journal of Cleaner Production

Abstract

The replacement of short-distance, low-occupancy automobile trips with electric bicycles (e-bikes) can reduce energy consumption and emissions related to transportation activities. Due to the low electricity consumption per mile of e-bikes compared to battery electric vehicles, e-bikes can also reduce the peak and total electric loads that battery electric vehicles impose on local and regional electricity systems, potentially translating into benefits for electricity system operation and distribution infrastructure lifetimes. This study leverages synthetic travel pattern data for the San Diego, California, region, along with National Household Travel Survey data for bike trip characteristics to estimate the battery electric vehicle trips that e-bikes can displace. Moreover, we use electricity system modeling to estimate the electricity system cost savings in the years 2030 and 2045 from replacing battery electric vehicle trips with e-bikes. We find that using e-bikes to displace battery electric vehicle trips where feasible can reduce California wholesale electricity system costs by up to 3.0% in 2030 and 3.8% in 2045, translating to annual savings of $770 million and $1360 million, respectively. Additional potential savings can also occur in the distribution system through extending the lifetime of distribution transformers, depending on the current loading of distribution transformers on a residential circuit.

Suggested Citation
Brian Tarroja, Kate Forrest, Kotaro Yamada, Ritun Saha and Michael Hyland (2025) “Estimating the electricity system benefits of scaling up E-bike usage in California”, Journal of Cleaner Production, 492, p. 144840. Available at: 10.1016/j.jclepro.2025.144840.

working paper

A Dynamic Forecasting System for Vehicle Markets with Clean-Fuel Vehicles

Abstract

This research deals with demand for automobiles and light-duty and medium-duty trucks. Planners concerned with energy consumption, air quality and the provision of transportation facilities must have dependable forecasts of vehicle ownership and use from both the residential (personal-use vehicle) sectors and the fleet (commercial and governmental sectors). As long as vehicles evolved slowly, it was possible to base such forecasts on extrapolations of observed demand. However, in an era of increasing environmental awareness, mandated in part by the US Clean Air Act Amendments (US EPA, 1990), government agencies are now concerned with promoting clean-fuel vehicles; vehicle manufacturers are faced with designing and marketing clean-fuel vehicles; and suppliers of fuels other than gasoline must plan infrastructure and pricing policies.

published journal article

Tracking daily travel; Assessing discrepancies between GPS-derived and self-reported travel patterns

Transportation Research Part C: Emerging Technologies

Abstract

Global Positioning Systems (GPS) technologies have been used in conjunction with traditional one- or two-day travel diaries to audit respondent reporting patterns, but we used GPS-based monitoring to conduct the first assessment to our knowledge of travel reporting patterns using a seven-day travel log instrument, which could reduce response burden and provide multiple-day, policy-relevant information for evaluation studies. We found substantial agreement between participant-reported daily travel patterns and GPS-derived patterns among 116 adult residents of a largely low-income and non-white transportation corridor in urbanized Los Angeles in 2011-2013. For all modes, the average difference between daily GPS- and log-derived trip counts was only about 0.39 trips and the average difference between daily GPS- and log-derived walking duration was about -11.8 min. We found that the probability that a day would be associated with agreement or discrepancies between these measurement tools varied by travel mode and participant socio-demographic characteristics. Future research is needed to investigate the potential and limitations of this and other self-report instruments for a larger sample and a wider range of population groups and travel patterns. (C) 2014 Elsevier Ltd. All rights reserved.

Suggested Citation
Douglas Houston, Thuy T. Luong and Marlon G. Boarnet (2014) “Tracking daily travel; Assessing discrepancies between GPS-derived and self-reported travel patterns”, Transportation Research Part C: Emerging Technologies, 48, pp. 97–108. Available at: 10.1016/j.trc.2014.08.013.