published journal article
Tour-based truck demand modeling with entropy maximization using GPS data
Journal of Advanced Transportation
Publication Date
December 1, 2019
Archives: Research Products
conference paper
The importance of HEV fuel economy and two research gaps preventing real world implementation of optimal energy management
SAE technical paper series
Publication Date
January 10, 2017
Author(s)
Zachary D. Asher, Van Wifvat, Anthony Navarro, Scott Samuelsen, Thomas Bradley
Abstract
Optimal energy management of hybrid electric vehicles has previously been shown to increase fuel economy (FE) by approximately 20% thus reducing dependence on foreign oil, reducing greenhouse gas (GHG) emissions, and reducing Carbon Monoxide (CO) and Mono Nitrogen Oxide (NOx) emissions. This demonstrated FE increase is a critical technology to be implemented in the real world as Hybrid Electric Vehicles (HEVs) rise in production and consumer popularity. This review identifies two research gaps preventing optimal energy management of hybrid electric vehicles from being implemented in the real world: sensor and signal technology and prediction scope and error impacts. Sensor and signal technology is required for the vehicle to understand and respond to its environment; information such as chosen route, speed limit, stop light locations, traffic, and weather needs to be communicated to the vehicle. Since optimal control requires accurate prediction of the vehicle environment and drive cycle, prediction scope and error impact analysis is needed to understand the required accuracy of sensor and signal information received by the vehicle as well as the accuracy of the optimal control computed. This review presents the current state of research and solutions in development for each of these research gaps. Once these research gaps have been filled, HEVs may have the potential to substantially increase the FE standard and remove ICE vehicles as the leading consumer of petroleum and leading contributor of GHG, CO, and NOx emissions.
Suggested Citation
Zachary D. Asher, Van Wifvat, Anthony Navarro, G. Scott Samuelsen and Thomas Bradley (2017) “The importance of HEV fuel economy and two research gaps preventing real world implementation of optimal energy management”, in SAE technical paper series. SAE International. Available at: 10.4271/2017-26-0106. Phd Dissertation
The Perception-Intention-Adaptation (PIA) Model: A theoretical framework for examining the effect of behavioral intention and neighborhood perception on travel behavior
Publication Date
January 1, 2013
Author(s)
Areas of Expertise
Abstract
Recent research has indicated convincing evidence of a link between characteristics of the built environment and travel behavior. However, few land use—travel behavior studies include cognitive factors (such as attitudes, perceptions, and environmental norms) that have been found to affect travel mode choice in the social psychology literature. This dissertation develops and empirically tests a theoretical framework called the Perception-Intention-Adaptation (PIA) model that brings land use and attitude-behavior theory together in order to address gaps in the travel behavior literature. Following a detailed description of the PIA model, the dissertation is comprised of three empirical essays. The analyses in these essays are based on cross-sectional and panel data collected during the Expo Line Study, the first experimental-control, before-and-after evaluation of a rail transit investment in California. The first essay evaluates the predictive power of the core socio-psychological constructs of the PIA (attitudes, norms, and control beliefs) in combination with a comprehensive set of built environment and socio-economic measures. Regression models of transit use are used to analyze cross-sectional data obtained before the opening of the Exposition light rail line in Los Angeles. The analysis indicates that two PIA constructs, attitudes toward public transportation and concerns about personal safety, significantly improve the model fit and were robust predictors of transit use, independent of built environment factors. The second essay uses panel data collected before and after the opening of the Exposition light rail line to examine changes in travel behavior. A quasi-experimental approach with experimental (within ½ mile of an Expo station) and control (beyond ½ mile) households is used to evaluate the travel effects of the opening of the Expo line at the household level. The results show a statistically significant reduction in vehicle miles traveled (VMT) in the experimental group, though overall transit ridership and travel-related physical activity did not change significantly. The final essay uses the before and after opening panel data to examine socio-psychological aspects of travel behavior change in response to the Expo Line opening. Random effects models of transit use, car driver trips, and active travel trips all show that the socio-psychological constructs hypothesized in the PIA model do have a significant impact on travel behavior. In addition, cross-lagged models designed to examine the attitude-behavior relationship show an apparent causal pathway from attitudes to behavior for all three travel outcomes.
Suggested Citation
Steven Paul Spears (2013) The Perception-Intention-Adaptation (PIA) Model: A theoretical framework for examining the effect of behavioral intention and neighborhood perception on travel behavior. Ph.D.. University of California, Irvine. Available at: https://uci.primo.exlibrisgroup.com/permalink/01CDL_IRV_INST/1gpb62p/alma991034268399704701 (Accessed: October 13, 2023). published journal article
Outdoor ambient air pollution and breast cancer survival among California participants of the Multiethnic Cohort Study
Environment International
Publication Date
March 1, 2022
Author(s)
Iona Cheng, Johnny Yang, Chiuchen Tseng, Jun Wu, Shannon M. Conroy, Salma Shariff-Marco, Scarlett Lin Gomez, Alice S. Whittemore, Daniel O. Stram, Loïc Le Marchand, Lynne R. Wilkens, Beate Ritz, Anna H. Wu
Abstract
Background Within the Multiethnic Cohort (MEC), we examined the association between air pollution and mortality among African American, European American, Japanese American, and Latina American women diagnosed with breast cancer. Methods We used a land use regression (LUR) model and kriging interpolation to estimate nitrogen oxides (NOx , NO2) and particulate matter (PM2.5, PM10) exposures for 3,089 breast cancer cases in the MEC, who were diagnosed from 1993 through 2013 and resided largely in Los Angeles County, California. Cox proportional hazards models were used to examine the association of time-varying air pollutants with all-cause, breast cancer, cardiovascular disease (CVD), and non-breast cancer/non-CVD mortality, accounting for key covariates. Results We identified 1,125 deaths from all causes (474 breast cancer, 272 CVD, 379 non-breast cancer/non-CVD deaths) among the 3,089 breast cancer cases with 8.1 years of average follow-up. LUR and kriged NOX (per 50 ppb) and NO2 (per 20 ppb), PM2.5 (per 10 µg/m3), and PM10 (per 10 µg/m3) were positively associated with risks of all-cause (Hazard Ratio (HR) range = 1.13–1.25), breast cancer (HR range = 1.19–1.45), and CVD mortality (HR range = 1.37–1.60). Associations were statistically significant for LUR NOX and CVD mortality (HR = 1.60; 95% CI: 1.08–2.37) and kriged NO2 and breast cancer mortality (HR = 1.45; 95% CI 1.02–2.07). Gaseous and PM pollutants were positively associated with breast cancer mortality across racial/ethnic group. Conclusion In this study, air pollutants have a harmful impact on breast cancer survival. Additional studies should evaluate potential confounding by socioeconomic factors. These data support maintaining clean air laws to improve survival for women with breast cancer.
Suggested Citation
Iona Cheng, Juan Yang, Chiuchen Tseng, Jun Wu, Shannon M. Conroy, Salma Shariff-Marco, Scarlett Lin Gomez, Alice S. Whittemore, Daniel O. Stram, Loïc Le Marchand, Lynne R. Wilkens, Beate Ritz and Anna H. Wu (2022) “Outdoor ambient air pollution and breast cancer survival among California participants of the Multiethnic Cohort Study”, Environment International, 161, p. 107088. Available at: 10.1016/j.envint.2022.107088. conference paper
What is the Optimal Fleet Size for Online Food Delivery Companies?– An Application to San Francisco
Transportation Research Board 100th Annual Meeting
Publication Date
January 1, 2021
Author(s)
Suggested Citation
Bumsub Park and Jean-Daniel M. Saphores (2021) “What is the Optimal Fleet Size for Online Food Delivery Companies?– An Application to San Francisco”. Transportation Research Board 100th Annual Meeting. Available at: https://trid.trb.org/view/1759433 (Accessed: October 11, 2023). published journal article
On the Costs of Air Pollution from Motor Vehicles
Journal of Transport Economics and Policy
Publication Date
January 1, 1995
Author(s)
Suggested Citation
Kenneth A. Small and Camilla Kazimi (1995) “On the Costs of Air Pollution from Motor Vehicles”, Journal of Transport Economics and Policy, 29(1), pp. 7–32. Available at: https://www.jstor.org/stable/20053058. research report
A vehicle ownership and utilization choice model with endogenous residential density
Publication Date
September 1, 2014
Associated Project
Author(s)
Suggested Citation
David Brownstone and Hao (Audrey) Fang (2014) A vehicle ownership and utilization choice model with endogenous residential density. Final Report UCTC-FR-2010-04, p. 135. Available at: https://escholarship.org/uc/item/2hc4h6h5.Related Publications
published journal article |
Sep 2014
A vehicle ownership and utilization choice model with endogenous residential density
Journal of Transport and Land Use
conference paper
San Diego's interstate 15 congestion pricing project - Traffic-related issues
TRANSPORTATION AND PUBLIC POLICY 2002: PLANNING AND ADMINISTRATION
Publication Date
January 1, 2002
Author(s)
J Supernak, Jacqueline Golob, Thomas Golob, C Kaschade, Camilla Kazimi, E Schreffler, D Steffey
Abstract
Traffic-related findings from the evaluation of the Interstate 15 (I-15) congestion pricing project are summarized. The project was a 3-year demonstration that allowed single-occupant vehicles (SOVs) to use the existing I-15 high-occupancy-vehicle (HOV) lanes, known as the I-15 express lanes, for a fee. San Diego State University conducted an independent, multielement evaluation of the I-15 pricing project to assess its impacts for both the ExpressPass and FasTrak phases of this demonstration. The primary project goals were (a) to maximize use of the existing I-15 express lanes, (b) to test whether allowing solo drivers to use the express lanes’ excess capacity could help relieve congestion on the I-15 main lanes, (c) to fund new transit and HOV improvements in the I-15 corridor, and (d) to use a market-based approach to set tolls. At the end of 1999, the I-15 pricing project was meeting its primary objectives. There was substantially better utilization of the express lanes. Both ExpressPass and FasTrak were feasible solutions for generating sufficient revenue to fund the new express bus service, called Inland Breeze. Neither ExpressPass nor FasTrak negatively affected carpool volumes on the express lanes; FasTrak was able to redistribute volumes from the middle of the peak to the peak shoulders. Free-flow conditions were maintained at virtually all times. The project’s primary benefit was the reliability of ontime arrival for users. The project was also able to slightly alleviate congestion on the I-15 main lanes. SOV violation rates in the I-15 express lanes remained substantially below the preproject level. Also discussed are the air quality, delay, and park-and-ride impacts of the project.
Suggested Citation
J Supernak, J Golob, TF Golob, C Kaschade, C Kazimi, E Schreffler and D Steffey (2002) “San Diego's interstate 15 congestion pricing project - Traffic-related issues”, in TRANSPORTATION AND PUBLIC POLICY 2002: PLANNING AND ADMINISTRATION. TRANSPORTATION RESEARCH BOARD NATL RESEARCH COUNCIL (Transportation research record), pp. 43–52. published journal article
Fuel reduction and electricity consumption impact of different charging scenarios for plug-in hybrid electric vehicles
Journal of Power Sources
Publication Date
August 1, 2011
Author(s)
Abstract
Plug-in hybrid electric vehicles (PHEVs) consume both gasoline and grid electricity. The corresponding temporal energy consumption and emission trends are valuable to investigate in order to fully understand the environmental benefits. The 24-h energy consumption and emission profile depends on different vehicle designs, driving, and charging scenarios. This study assesses the potential energy impact of PHEVs by considering different charging scenarios defined by different charging power levels, locations, and charging time. The region selected for the study is the South Coast Air Basin of California. Driving behaviors are derived from the National Household Travel Survey 2009 (NHTS 2009) and vehicle parameters are based on realistic assumptions consistent with projected vehicle deployments. Results show that the reduction in petroleum consumption is significant compared to standard gasoline vehicles and the ability to operate on electricity alone is crucial to cold start emission reduction. The benefit of higher power charging on petroleum consumption is small. Delayed and average charging are better than immediate charging for home, and non-home charging increases peak grid loads. (C) 2011 Elsevier B.V. All rights reserved.
Suggested Citation
Li Zhang, Tim Brown and G. Scott Samuelsen (2011) “Fuel reduction and electricity consumption impact of different charging scenarios for plug-in hybrid electric vehicles”, Journal of Power Sources, 196(15), pp. 6559–6566. Available at: 10.1016/j.jpowsour.2011.03.003. published journal article
Traffic-related air pollution and Parkinson's disease in central California
Environmental Research
Publication Date
January 1, 2024
Abstract
Background Prior studies suggested that air pollution exposure may increase the risk of Parkinson’s Disease (PD). We investigated the long-term impacts of traffic-related and multiple sources of particulate air pollution on PD in central California. Methods Our case-control analysis included 761 PD patients and 910 population controls. We assessed exposure at residential and occupational locations from 1981 to 2016, estimating annual average carbon monoxide (CO) concentrations – a traffic pollution marker – based on the California Line Source Dispersion Model, version 4. Additionally, particulate matter (PM2.5) concentrations were based on a nationwide geospatial chemical transport model. Exposures were assessed as 10-year averages with a 5-year lag time prior to a PD diagnosis for cases and an interview date for controls, subsequently categorized into tertiles. Logistic regression models were used, adjusting for various factors. Results Traffic-related CO was associated with an increased odds ratio for PD at residences (OR for T3 vs. T1: 1.58; 95% CI: 1.20, 2.10; p-trend = 0.02) and workplaces (OR for T3 vs. T1: 1.91; 95% CI: 1.22, 3.00; p-trend <0.01). PM2.5 was also positively associated with PD at residences (OR for T3 vs. T1: 1.62; 95% CI: 1.22, 2.15; p-trend <0.01) and workplaces (OR for T3 vs. T1: 1.85; 95% CI: 1.21, 2.85; p-trend <0.01). Associations remained robust after additional adjustments for smoking status and pesticide exposure and were consistent across different exposure periods. Conclusion We found that long-term modeled exposure to local traffic-related air pollution (CO) and fine particulates from multiple sources (PM2.5) at homes and workplaces in central California was associated with an increased risk of PD.