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Cambridge, United Kingdom

Zhang L.,Cambridge Systematics Inc. | Prevedouros P.D.,University of Hawaii at Manoa

Delay has been selected as the only measure for determining signalized intersection level-of-service (LOS). Previous studies reported that road users consider multiple factors in their evaluation of LOS, including traffic-related and non-traffic factors. The findings from more than 1300 responses to a web-based stated-preference survey suggest that road users consider multiple factors for the evaluation of signalised intersections. A methodology based on fuzzy logic is presented in this article to determine the signalised intersection LOS that explicitly accounts for user perceptions. To reflect the fuzziness of user perceptions, rigid LOS thresholds were replaced with fuzzy numbers. Fuzzy inferences were applied to combine important factors at signalised intersections for deriving a composite LOS measure. A case study with different improvement scenarios was conducted to illustrate the proposed method. Overall, the fuzzy logic method simulates the human reasoning process and provides a feasible alternative to quantify the user perceptions of signalised intersection LOS. © 2011 Hong Kong Society for Transportation Studies Limited. Source

Paleti R.,University of Texas at Austin | Copperman R.B.,Cambridge Systematics Inc. | Bhat C.R.,University of Texas at Austin

Children are an often overlooked and understudied population group, whose travel needs are responsible for a significant number of trips made by a household. In addition, children's travel and activity participation during the post-school period have direct implication for adults' activity-travel patterns. A better understanding of children's after school activity-travel patterns and the linkages between parents and children's activity-travel needs is necessary for accurate prediction and forecasting of activity-based travel demand modeling systems. In this paper, data from the 2002 Child Development Supplement of the Panel Study of Income Dynamics is used to undertake a comprehensive assessment of the post-school out-of-home activity-location engagement patterns of children aged 5-17 years. Specifically, this research effort utilizes a multinomial logit model to analyze children's post-school location patterns, and employs a multiple discrete-continuous extreme value model to study the propensity of children to participate in, and allocate time to, multiple activity episode purpose-location types during the after-school period. The results show that a wide variety of demographic, attitudinal, environmental, and others' activity-travel pattern characteristics impact children's after school activity engagement patterns. © 2010 Springer Science+Business Media, LLC. Source

El-Geneidy A.M.,McGill University | Horning J.,Cambridge Systematics Inc. | Krizek K.J.,University of Colorado at Denver
Journal of Advanced Transportation

The widespread adoption of automated vehicle location (AVL) systems and automatic passenger counters (APCs) in the transit industry has opened new venues in operations and system monitoring. In 2005, Metro Transit, Minnesota, implemented AVL system and partially implemented APC technologies. To date there has been little effort to employ the collected data in evaluating transit performance. This research uses such data to assess performance issues along a cross-town route in the Metro Transit system. We generate a series of visual and analytical analyses to predict run time, schedule adherence and reliability of the transit route at two scales: the time point segment and the route level to demonstrate ways of identifying causes of decline in reliability levels. The analytical models show that while headways are maintained, schedule revisions are needed to improve run time and schedule adherence. Finally, the analysis suggests that many scheduled stops along this route are underutilized and recommends stop consolidation as a tool to decrease variability of service through concentrating passenger demand along a fewer number of stops. © 2010 John Wiley and Sons, Ltd. Source

Weinblatt H.,Cambridge Systematics Inc.
Transportation Research Record

Recent increases in motorcycle fatalities, in the rate of motorcycle fatalities per vehicle mile of travel (VMT), and in the ratio of estimated motorcycle VMT to motorcycle registrations have resulted in greater attention to motorcycle safety and to related motorcycle statistics. Technologies that are currently used for collecting counts of vehicles by vehicle class or that have been proposed for use in counting motorcycles are reviewed. Available information about the quality of motorcycle counts produced by these technologies is discussed. Several recommendations for improving the quality of motorcycle counts and count-based VMT estimates for Class 1 vehicles are included. Also discussed are some factors that are likely to have contributed to the observed divergence between the growth rates of motorcycle registrations and those of motorcycle VMT estimates. The use of registration or insurance company data, or both, for estimating VMT of these vehicles without the use of count data is briefly discussed. Source

Destro L.,Cambridge Systematics Inc. | Holguin-Veras J.,Rensselaer Polytechnic Institute
Transportation Research Record

Volunteers, emergency respondents, the press, and material donations converge at an area affected by an extreme event. The convergence of materials is a highly heterogeneous flow of goods, ranging from critical supplies to large influxes of low-priority goods. These low-priority goods can hamper the flow of critical supplies because of the allocation of resources required to manage them and because these resources distract from other, more critical tasks. This problem is a major issue: not knowing the volume of material convergence that might be expected after a disaster makes it difficult for relief agencies to prepare. This paper contributes to the study of this subject through the econometric estimation of models that attempt to explain the convergence as a function of the socioeconomic characteristics of the donors. The models are estimated with the use of a database of donations made after Hurricane Katrina; the database was created by postprocessing of articles in the media. The models show that donations have a systematic relation with the donors' socioeconomic characteristics. In general, donations have a positive relation with income, education, number of married individuals, total population, and household density and a negative relation with unemployment, number of unmarried individuals, and family size. The models indicate that monetary donations increase with the distance from the donor to the affected site, whereas the value of in-kind donations decreases with distance. This finding reflects the role played by transportation costs in deterring donors located further away from sending large volumes of physical goods. Source

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