published journal article

Projecting use of electric vehicles from household vehicle trials

Transportation Research Part B: Methodological

Publication Date

September 1, 1998

Abstract

Vehicle trials are an important source of information about how households would use battery electric vehicles. However, trial data are potentially biased because the novelty of the trial can introduce short-term changes in driving patterns and a positive effect for the technology can result from giving respondents special attention. In this study we examine these methodological issues using data collected from travel diaries and pre-trial and post-trial surveys as part of an extensive trial of prototype electric vehicles conducted by a major vehicle manufacturer. Households demonstrated that they can use the electric vehicle to make most of the everyday trips that were previously made on a conventional-fuel vehicle, but some trips will be shifted to other vehicles in the household’s fleet. However, experience with electric vehicles does not change perceptions of desired vehicle range. Keeping a travel diary gave users direct feedback that they were usually travelling less than 50 miles per day, but there remained an expectation that vehicles should have a range of 100 miles or more. (C) 1998 Elsevier Science Ltd. All rights reserved.

Suggested Citation
Thomas F. Golob and Jane Gould (1998) “Projecting use of electric vehicles from household vehicle trials”, Transportation Research Part B: Methodological, 32(7), pp. 441–454. Available at: 10.1016/s0191-2615(98)00001-0.

conference paper

Online classification using a voted RDA method

Proceedings of the twenty-eighth aaai conference on artificial intelligence

Publication Date

January 1, 2014

Author(s)

Tianbing Xu, Jianfeng Gao, Lin Xiao, Amelia Regan

Abstract

We propose a voted dual averaging method for online classification problems with explicit regularization. This method employs the update rule of the regularized dual averaging (RDA) method proposed by Xiao, but only on the subsequence of training examples where a classification error is made. We derive a bound on the number of mistakes made by this method on the training set, as well as its generalization error rate. We also introduce the concept of relative strength of regularization, and show how it affects the mistake bound and generalization performance. We examine the method using l(1)-regularization on a large-scale natural language processing task, and obtained state-of-the-art classification performance with fairly sparse models.

Suggested Citation
Tianbing Xu, Jianfeng Gao, Lin Xiao and Amelia C. Regan (2014) “Online classification using a voted RDA method”, in Proceedings of the twenty-eighth aaai conference on artificial intelligence. ASSOC ADVANCEMENT ARTIFICIAL INTELLIGENCE, pp. 2170–2176.

Phd Dissertation

Driver Response to Variable Message Signs in a 2D Multiplayer Real-time Driving Simulator

Abstract

This research seeks to understand how information displayed by variable message signs (VMS) can affect driver route-choice and be better used for active traffic incident management. I study the effect of various VMS messaging strategies using a money incentivized behavioral experiment with a novel 2D real-time driving simulator that supports dozens of subjects driving on a shared virtual roadway where traffic incidents unpredictably occur. Drivers are shown a VMS display before choosing between two congestible routes. I conducted this experiment with students at the UCI Experimental Social Science Laboratory (ESSL) and with a more diverse sample of online subjects crowdsourced from the Amazon Mechanical Turk (MTurk) marketplace. Chapter 1 will present the research motivation and methodology, the design and implementation of the experiment platform, and the results with student subjects. I find that subjects learned to efficiently operate the driving simulator, all tested VMS messaging strategies improved aggregate outcomes compared to the No VMS baseline, displaying messages didn’t cause highly volatile diversion rates, and subject gender exhibited consistent correlations with route choice. Chapter 2 will discuss the reasons for replicating on MTurk, the methodological modifications necessary to conduct the experiment online, and how the MTurk results compare to the student results. I find that it’s viable but challenging to conduct real-time multiplayer experiments on MTurk, there are significant differences in individual characteristics between the MTurk and student subjects, and there are limited behavioral differences between the two groups. Chapter 3 will introduce a framework using long short-term memory (LSTM) neural networks to predict driver route choice using real-time contextual data. I use varyingly limited vectors of data from my driving simulator experiments as the neural network’s input to predict driver route choice at the decision point between the two available routes. I find that the best performing model configuration can predict individual route choice with 74.0% average accuracy with in-sample cross validation and 72.2% average accuracy with out-of-sample validation.

Suggested Citation
SI-YUAN KONG (2018) Driver Response to Variable Message Signs in a 2D Multiplayer Real-time Driving Simulator. PhD Dissertation. UC Irvine. Available at: https://escholarship.org/uc/item/47j7b206.

working paper

Subsidized Shared-Ride Taxi Services

Publication Date

December 1, 1979

Author(s)

Roger Teal, James V. Marks, Richard E. Goodhue

Working Paper

UCI-ITS-WP-79-4

Areas of Expertise

Abstract

When provided by taxi firms under contract to public agencies, demand responsive transit is essentially subsidized shared-ride taxi (SRT) service. With taxi firms increasingly seek ing, and finding, opportunities to become public transit contractors for the delivery of community level transit services, subsidized SRT seems destined to become an important revenue source for taxi firms and a major form of publicly supported paratransit. In California, subsidized SRT has already become the predominant form of demand responsive transit, with 29 such systems presently operating in the State. Based on a study of California’s experiences with subsidized SRT, this paper analyzes the issues associated with this recent paratransit development. One general set of issues concern service provision, including the institutional reasons for contracting, competition for contracts, contractual arrangements and their effects, and the cost-efficiency of subsidized SRT. A second major set of issues concern the consequences for taxi firms of becoming public transit providers, including legal implications, operational changes, labor-management relations, the impact of subsidization, and the effects of contracting on the firm’s financial situation and future plans. This issue analysis provides the basis for a discussion of the policy implications of California’s SRT experiences.

Suggested Citation
Roger F. Teal, James V. Marks and Richard E. Goodhue (1979) Subsidized Shared-Ride Taxi Services. Working Paper UCI-ITS-WP-79-4. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/1js907tw.

published journal article

Understanding the effects of socioeconomic factors on housing price appreciation using explainable AI

Applied Geography

Abstract

Housing price appreciation is an important socioeconomic phenomenon that captures the complex socioeconomic dynamics of a city. Variation in housing price appreciation across neighborhoods reflects localized housing demand and supply-side factors. This study develops quality-adjusted, census tract-level housing price indices using a fine-grained big dataset containing a total of 140,289 housing transactions in the County of Los Angeles. We employ the SHapley Additive exPlanations (SHAP) technique, an explainable artificial intelligence framework, to examine the underlying demographic and socioeconomic factors that help in explaining the variance in tract-level housing price appreciation from 2012 through 2018 in the County of Los Angeles. The novelty of the methodology lies in the local interpretation of spatial patterns it provides from big data in the urban context and in assessing how the factors influencing housing price appreciation vary geographically. The modeling framework could help planners in making informed decisions about local geographic contexts that contribute to variability in housing price appreciation in cities.

Suggested Citation
Shengxiang Jin, Huixin Zheng, Nicholas Marantz and Avipsa Roy (2024) “Understanding the effects of socioeconomic factors on housing price appreciation using explainable AI”, Applied Geography, 169, p. 103339. Available at: 10.1016/j.apgeog.2024.103339.

conference paper

How does fear of sexual harassment on transit affect women's use of transit?

Proceedings of women's issues in transportation: Summary of the 4th international conference, vol. 2: Technical papers, transportation research board conference proceeding 46, washington DC

Publication Date

January 1, 2011

Author(s)

Suggested Citation
Hsin-Ping Hsu (2011) “How does fear of sexual harassment on transit affect women's use of transit?”, in Proceedings of women's issues in transportation: Summary of the 4th international conference, vol. 2: Technical papers, transportation research board conference proceeding 46, washington DC, pp. 85–94.

working paper

Highways and Intrametropolitan Employment Growth

Publication Date

April 1, 1995

Associated Project

Author(s)

Working Paper

UCI-ITS-WP-95-9, UCTC 85

Areas of Expertise

Abstract

This paper examines the link between highways and employment growth within two metropolitan areas. Most studies of the land use impacts of transportation focus on residential location. yet in decentralized urban areas, the relationship between the highway network and intrametropolitan employment location is an important one. This paper uses an econometric model of local employment growth to examine the effect of highways on employment changes within northern New Jersey and Orange County, California. Within both urban areas, highway proximity has a statistically significant and positive effect on employment growth. There is also evidence that other location specific amenities (such as agglomeration economies and surrounding population growth) are possibly more important for local employment growth than highway location.

Suggested Citation
Marlon G. Boarnet (1995) Highways and Intrametropolitan Employment Growth. Working Paper UCI-ITS-WP-95-9, UCTC 85. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/7cd0157q.

published journal article

Lane Management Strategies in a Connected Environment: Analysis of Freight Corridor Scenarios for I-710 in Southern California

Transportation Research Record: Journal of the Transportation Research Board

Publication Date

February 1, 2024

Abstract

Connected vehicles (CVs) and their supporting infrastructure are expected to play an important role in the management of traffic congestion. As highway expansion projects are becoming less common, deploying emerging technologies is essential to make the most of the current road infrastructure. Most published studies report that CVs improve traffic performance only marginally. Here, we propose that CVs drive cooperatively with cooperative adaptive cruise control (CACC)-enabled vehicles by designating a CACC lane for periods with high flows of slow-moving heavy-duty drayage trucks. To assess if this approach could help absorb year 2035 projected drayage traffic increases at the Ports of Los Angeles and Long Beach, which is the largest port complex in the U.S.A., we analyze three 2035 scenarios for I-710, a key freeway for freight transportation in Southern California: (1) CACC-enabled vehicles are deployed under mixed traffic conditions; (2) CACC-enabled vehicles are restricted to the first lane (left-most lane); (3) the first lane is reserved for CACC-enabled vehicles, and access is optional. Our results suggest that substantial speed improvements can be obtained, but only when the first lane is CACC reserved with optional access, because this approach creates more platooning opportunities and thus helps maximize the benefits of CACC.

Suggested Citation
Monica Ramirez-Ibarra and Jean-Daniel M. Saphores (2024) “Lane Management Strategies in a Connected Environment: Analysis of Freight Corridor Scenarios for I-710 in Southern California”, Transportation Research Record: Journal of the Transportation Research Board, 2678(2), pp. 620–634. Available at: 10.1177/03611981231175903.

conference paper

Simultaneous state and parameter estimation in newell's simplified kinematic wave model with heterogeneous data

Proceedings of the 94th annual meeting of the transportation research board

Publication Date

January 1, 2015

Abstract

Traffic state estimation provides valuable information for travelers and decision makers. To implement an estimation method, one needs to predetermine the initial state and model parameters. This paper presents a new method to estimate model parameters and initial states for Newellâ??s simplified kinematic wave model based on heterogeneous data sources. Different from existing studies, the proposed method is a simultaneous framework which estimates both parameter and traffic state at the same step. The problem is formulated in a least square optimization framework which is solved using the Gauss-Newton method. The authors verified the estimation method using Next Generation Simulation (NGSIM) (USDOT, 2008) data and analyzed the impact of market penetration rate. The estimation result is consistent with observation.

Suggested Citation
Zhe Sun, Wen-Long Jin and Stephen G. Ritchie (2015) “Simultaneous state and parameter estimation in newell's simplified kinematic wave model with heterogeneous data”, in Proceedings of the 94th annual meeting of the transportation research board, p. 22p.

published journal article

Environmental Impacts of Transportation Network Company (TNC)/Ride-Hailing Services: Evaluating Net Vehicle Miles Traveled and Greenhouse Gas Emission Impacts within San Francisco, Los Angeles, and Washington, D.C. Using Survey and Activity Data

Sustainability

Publication Date

August 28, 2024

Author(s)

Elliot Martin, Susan Shaheen, Brooke Wolfe

Abstract

Transportation Network Companies (TNCs) play a prominent role in mobility within cities across the globe. However, their activity has impacts on vehicle miles traveled (VMT) and greenhouse gas (GHG) emissions. This study quantifies the change in personal vehicle ownership and total miles driven by TNC drivers in three metropolitan areas: San Francisco, CA; Los Angeles, CA; and Washington, D.C. The data sources for this analysis comprise two surveys, one for TNC passengers (N = 8630) and one for TNC drivers (N = 5034), in addition to data provided by the TNC operators Uber and Lyft. The passenger survey was deployed within the three metropolitan areas in July and August 2016, while the driver survey was deployed from October to November 2016. The TNC operator data corresponded with these time frames and informed the distance driven by vehicles, passenger frequency of use, and fleet level fuel economies. The data from these sources were analyzed to estimate the impact of TNCs on travel behavior, personal vehicle ownership and associated VMT changes, as well as the VMT of TNCs, including app-off driving. These impacts were scaled to the population level and collectively evaluated to determine the net impacts of TNCs on VMT and GHG emissions using fuel economy factors. The results showed that the presence of TNCs led to a net increase of 234 and 242 miles per passenger per year, respectively, in Los Angeles and San Francisco, while yielding a net decrease of 83 miles per passenger per year in Washington, D.C. A sensitivity analysis evaluating net VMT change resulting from vehicle activity and key behavioral impacts revealed the conditions under which TNCs can contribute to transportation sustainability goals.

Suggested Citation
Elliot Martin, Susan Shaheen and Brooke Wolfe (2024) “Environmental Impacts of Transportation Network Company (TNC)/Ride-Hailing Services: Evaluating Net Vehicle Miles Traveled and Greenhouse Gas Emission Impacts within San Francisco, Los Angeles, and Washington, D.C. Using Survey and Activity Data”, Sustainability, 16(17), p. 7454. Available at: 10.3390/su16177454.