book/book chapter
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research report
Near-Source Modeling of Transportation Emissions in Built Environments Surrounding Major Arterials
Publication Date
Associated Project
Author(s)
Research Report
Areas of Expertise
Abstract
Project included three major parts: 1) field measurements of particulate matter in five urban areas, 2) laboratory modeling of flow and dispersion within model urban areas, and 3) numerical modeling. Project website and database are located at http://emissions.engr.ucr.edu/.
Suggested Citation
Marlon Boarnet, RUFUS D EDWARDS, Jun Wu, GAVIN FERGUSON, Anahita Fazl and RAUL PEREZ LEJANO (2009) Near-Source Modeling of Transportation Emissions in Built Environments Surrounding Major Arterials. Research Report UCTC 886. ITS-Irvine. Available at: https://escholarship.org/uc/item/5w357946.conference paper
A distributed, scalable, and synchronized framework for large-scale microscopic traffic simulation
Proceedings. 2005 IEEE intelligent transportation systems, 2005.
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Author(s)
Suggested Citation
Raymond Klefstad, Yue Zhang, Mingjie Lai, R Jayakrishnan and Riju Lavanya (2005) “A distributed, scalable, and synchronized framework for large-scale microscopic traffic simulation”, in Proceedings. 2005 IEEE intelligent transportation systems, 2005.. IEEE / IEEE, pp. 813–818. Available at: 10.1109/itsc.2005.1520154.conference paper
Using mobile tracking technologies to characterize air pollution exposure in major goods movement corridors
Proceedings of the annual meeting of the association of collegiate schools of planning (ACSP), cincinnati, OH
Publication Date
Author(s)
Suggested Citation
D. Houston, G. Jaimes, J. Wu and D. Yang (2012) “Using mobile tracking technologies to characterize air pollution exposure in major goods movement corridors”, in Proceedings of the annual meeting of the association of collegiate schools of planning (ACSP), cincinnati, OH.working paper
Short Term Freeway Traffic Flow Prediction Using Genetically-Optimized Time-Delay-Based Neural Networks
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Associated Project
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Abstract
Proper prediction of traffic flow parameters is an essential component of any proactive traffic control system and one of the pillars of advanced management of dynamic traffic networks. In this paper, we present a new short term traffic flow prediction system based on an advanced Time Delay Neural Network (TDNN) model, the structure of which is optimized using a Genetic Algorithm (GA). After presentation of the model’s development, its performance is validated using both simulated and real traffic flow data obtained from the California Testbed in Orange County, California. The model predicts flow and occupancy values at a given freeway site based on contributions from their recent temporal profile as well the spatial contribution from neighboring sites. Both temporal and spatial effects were found essential for proper prediction. An in-depth investigation of the variables pertinent to traffic flow prediction was conducted examining the extent of the “look-back” interval, the extent of prediction in the future, the extent of spatial contribution, the resolution of the input data, and their effects on prediction accuracy. Results obtained indicate that the prediction errors vary inversely with the extent of the spatial contribution, and that the inclusion of three loop stations in both directions of the subject station is sufficient for practical purposes. Also, the longer the extent of prediction, the more the predicted values tend toward the mean of the actual, for which case the optimal look-back interval also shortens. Interestingly, it was found that coarser data resolution is better for longer extents of prediction. The implication is that the level of data aggregation/resolution should be comparable to the prediction horizon for best accuracy. The model performed acceptably using both simulated and real data. The model also showed potential to be superior to such other well-known neural network models as the Multi layer Feed-forward (MLF) when applied to the same problem. Keywords: Traffic Flow Prediction, Neural Networks, Genetic Algorithms, Traffic Management.
working paper
Structural Models of the Effects of the Commute Trip on Travel and Activity Participation
Working Paper
Areas of Expertise
Abstract
Travel demand is viewed as being derived from the demand for out-of-home activities. The journey to work can have a significant impact on the travel and activity patterns of workers and other household members. The objective of this research is to model the relationships between travel and activity participation and examine how these relationships are influenced by the time a worker spends commuting between home and his or her worksite. Causal hypotheses are tested using data from approximately 140 workers who responded to two waves of a panel survey collected as part of the State of California Telecommuting Pilot Project. These data contain detailed descriptions of all travel by the survey respondents over three working days in each of two years, 1988 and 1989. A structural equations model is specified in which the durations of four exhaustive categories of out-of-home activities – work, personal business, shopping and social/recreation -generate needs for time spent traveling, and durations and travel times are interrelated in a complex causal structure. The effects of the reduction in travel times for work by telecommuters in the second wave of the panel are captured in terms of additional structural parameters. Results indicate that telecommuting leads directly to increases in shopping activities and decreases in travel for social/recreational activities, and leads indirectly to changes in travel for all purposes. A general modeling framework in which activities and travel relationships can be studied is also discussed.
Suggested Citation
Thomas F. Golob and Ram M. Pendyala (1991) Structural Models of the Effects of the Commute Trip on Travel and Activity Participation. Working Paper UCI-ITS-WP-91-15, UCI-ITS-AS-WP-91-1. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/3hq9m5hp.published journal article
Comments
Brookings-Wharton Papers on Urban Affairs
Publication Date
Author(s)
Suggested Citation
Jan K. Brueckner and Douglas Holtz-Eakin (2000) “Comments”, Brookings-Wharton Papers on Urban Affairs, 2000(1), pp. 267–273. Available at: 10.1353/urb.2000.0014.published journal article
Intersectionality of individual and neighborhood-level adverse social determinants of health in early pregnancy
Pregnancy
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Author(s)
Abstract
Introduction Individual- and neighborhood-level social determinants of health (SDOH) have been assessed separately in pregnancy, but their relationship to one another remains uncertain. We investigated the intersectionality of three neighborhood-level SDOH measures with three individual-level SDOH measures. This was done to examine the concomitant experiences of multiple SDOH in pregnancy. Methods A secondary analysis of data from the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-To-Be. We assessed three neighborhood-level SDOH measures using geocoded participant home addresses in the first trimester at the census-tract level: (1) high socioeconomic disadvantage (in tertiles) by the 2015 Area Deprivation Index, (2) inadequate food access by the USDA Food Access Research Atlas, and (3) low walkability by the EPA National Walkability Score. We assessed three individual-level SDOH measures: low household income, lower educational attainment, and Medicaid insurance. We examined the combinations of these three neighborhood SDOH and three individual SDOH measures by graphical visualization and using statistical tests to assess overall differences in the distribution of these measures. Results Of 9588 nulliparous individuals, adverse neighborhood-level SDOH [high socioeconomic disadvantage (28%), inadequate food access (24%), and low walkability (66%)] and adverse individual-level SDOH [low household income (19%), lower educational attainment (23%), and Medicaid insurance (33%)] were common in early pregnancy. Six percent of individuals lived in a community with all three adverse neighborhood-level SDOH measures. Of those living in a community with at least two neighborhood-level SDOH measures, 23% lived in areas with inadequate food access and low walkability, 19% with high socioeconomic disadvantage and low walkability, and 1% with high socioeconomic disadvantage and inadequate food access. Overall, 23% lived in a community with no adverse neighborhood-level SDOH, and among this group, 88% had no adverse individual-level SDOH. There were significant differences in adverse individual-level SDOH based on whether individuals lived in a community with all three adverse neighborhood-level measures [low household income (39%), lower educational attainment (44%), Medicaid (55%)], any two measures [low household income (22%), lower educational attainment (27%), Medicaid (37%)], or only one measure [low household income (14%), lower educational attainment (17%), Medicaid (27%)] (p < 0.001 for all). Conclusion Among nulliparous individuals in early pregnancy, the frequency of adverse individual-level SDOH was generally higher when they lived in communities with more adverse neighborhood-level SDOH. Future approaches that identify and classify the multifaceted and multilevel nature of structural determinants as they relate to pregnancy outcomes are needed.
Suggested Citation
Jameaka L. Hamilton, William A. Grobman, Jiqiang Wu, Lynn M. Yee, David Haas, Becky Mcneil, Brian Mercer, Hyagriv Simhan, Uma Reddy, Robert M. Silver, Samuel Parry, George Saade, Jun Wu, Courtney D. Lynch and Kartik K. Venkatesh (2025) “Intersectionality of individual and neighborhood-level adverse social determinants of health in early pregnancy”, Pregnancy, 1(2), p. e70002. Available at: 10.1002/pmf2.70002.working paper
Population and Employment Densities: Structure and Change
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Associated Project
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Working Paper
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Abstract
We examine spatial patterns and their changes during the 1970s for the Los Angeles region, by estimating monocentric and polycentric density functions for employment and population. Downtown Los Angeles is clearly identified as the statistical monocentric center of the region, and it is the most consistently strong center in the polycentric patterns. Polycentric models fit statistically better than monocentric models, and there was some shift in employment distribution toward a more polycentric pattern. These findings verify the existence of polycentricity in Los Angeles and demonstrate for the first time that employment and especially population follow a polycentric pattern based on exogenously defined employment centers. The results confirm that both employment and population became more dispersed during the 1970s.
Suggested Citation
Kenneth A. Small and Shunfeng Song (1994) Population and Employment Densities: Structure and Change. Working Paper UCI-ITS-WP-93-5, UCTC 161. Institute of Transportation Studies, Irvine. Available at: https://escholarship.org/uc/item/6nk5v6b4.working paper
Home Environment Consequences of Commute Travel Impedance
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Abstract
The physical and perceptual dimensions of commuting travel impedance were again found to have stressful consequences in a study of 99 employees of two companies. This quasi-experimental replication study, which focuses here on home environment consequences, investigated the effects of physical impedance and subjective impedance on multivariate measures of residential satisfaction and personal affect in the home. Both sets of residential outcome measures were found to be significantly related to the two impedance dimensions. As predicted, gender was a significant moderator of physical impedance effects. Females commuting on high physical impedance routes were most negatively affected. Previously found subjective impedance effects on negative home mood, regardless of gender, were strongly replicated with several methods and were buttressed by convergent results with objective indices. The theoretical conjecture that subjective impedance mediates the stress effects of physical impedance was supported for the personal affect cluster but only for one variable in the residential satisfaction cluster. Traffic congestion has increased in metropolitan areas nationwide, and commuters, families, and organizations are absorbing associated hidden costs. The results are reviewed in terms of our ecological model, and the moderating effects of gender are discussed in terms of choice and role constraints.