Chen A.,Utah State University |
Ryu S.,Utah State University |
Chootinan P.,Transportation Engineer
Journal of Transportation Engineering | Year: 2010
Path flow estimator (PFE) is a single-level network observer proposed to estimate path flows and origin-destination flows from traffic counts in a transportation network. The PFE model handles the traffic count inconsistency problem by allowing user to specify appropriate error bounds (or confidence interval) on the traffic counts. This approach, although flexible, introduces a systematic bias in underestimating the total demand when improper error bounds are specified. This paper presents an L∞-norm PFE model that minimizes the systematic bias of the total demand estimate encountered in the PFE model by determining the least maximum absolute error needed to accommodate measurement errors and traffic count inconsistencies within the estimation process. A solution algorithm based on the dual formulation combined with a column generation procedure is developed for solving the proposed L∞-norm PFE model. Numerical results are presented to illustrate the features and applicability of the proposed L∞-norm PFE model and solution algorithm. © 2010 ASCE.
Schultz G.G.,Brigham Young University |
Black C.W.,Transportation Engineer |
Saito M.,Brigham Young University
T and DI Congress 2014: Planes, Trains, and Automobiles - Proceedings of the 2nd Transportation and Development Institute Congress | Year: 2014
A number of steps have been taken over the past several years to advance the Utah Department of Transportation safety initiative. Previous research began the development of a hierarchical Bayesian model to analyze crashes on Utah roadways. The model analyzes roadway segments and determines a posterior predictive distribution of crashes. The actual numbers of crashes for each segment are compared to the predictive distribution and a percentile is calculated. A high percentile indicates more crashes than would be expected and a low percentile indicates less. A Geographic Information System (GIS) framework was developed to facilitate the analysis. The GIS framework has the capability to format the raw data such that it can be read into the statistical model. The GIS framework also displays the numerical data output by the statistical model spatially, allowing for an easy and intuitive analysis of 'hot spots' or 'black spots.' The purpose of this paper is to outline the GIS framework for crash data analysis, the results of which can be used to further evaluate those segments classified as hot spots. © 2014 American Society of Civil Engineers.
Kattan L.,University of Calgary |
Tay R.,La Trobe University |
Acharjee S.,Transportation Engineer
Accident Analysis and Prevention | Year: 2011
Since speeding is one of the major causes of frequent and severe traffic accidents around school and playground areas, many jurisdictions have reduced the speed limits in these areas to protect children who may be at risk. This paper investigated the speed compliance, mean speed and 85th percentile speed at selected school and playground zones in the City of Calgary in Alberta. Our results showed that the mean speed was lower and the rate of compliance was higher in the school zone compared to the playground zone, 2 lane roads relative to 4 lane roads, roads with fencing, traffic control devices and the presence of speed display device or children, and zones that were longer (>200 m). Accordingly, this study provided recommendations to improve the effectiveness of school and playground zone speed limits. © 2011 Elsevier Ltd. All rights reserved.
Izadpanah P.,Transportation Engineer |
Nichol S.,Ontario Ministry of Transportation |
Hadayeghi A.,Transportation Engineering |
Institute of Transportation Engineers Annual Meeting and Exhibit 2012 | Year: 2012
Many road authorities recognize the challenges associated with a reactive approach to road safety and have adopted a proactive and systematic approach in their road safety initiatives. However, automation is a key challenge road authorities face in implementing an efficient and effective traffic safety management program. In the summer of 2009, the American Association of State Highway and Transportation Officials released the first version of SafetyAnalyst software, and in 2010 published the Highway Safety Manual. The Highway Safety Manual provides road safety knowledge and tools in a practical form to facilitate improved decision-making based on safety performance. The focus of the Highway Safety Manual is to provide quantitative information for decision-making. SafetyAnalyst software incorporates methodologies set forth in the Highway Safety Manual for road safety management in computerized analytical tools. These tools support the identification of safety improvement needs and the decisionmaking process for developing a system-wide program of safety improvement projects. The Ministry of Transportation of Ontario has initiated a project to configure SafetyAnalyst to meet their needs in managing the road safety analysis of their highway network. In this initiative, all four SafetyAnalyst analysis modules, which include the Network Screening Tool, Diagnosis Tool, Countermeasure Selection Tool, Economic Appraisal Tool, Priority Ranking Tool, and Countermeasure Evaluation Tool, are configured for the road network under the jurisdiction of the Ministry of Transportation of Ontario. As part of this initiative, the Ministry's Safety Performance Functions are being updated for road sections, interchanges, ramps, ramp terminals, and intersections. The functional forms of these safety performance functions are compatible with those of SafetyAnalyst. Moreover, the SafetyAnalyst modules are configured with Ontario's customized values. The main goal of this paper is to summarize the lessons learned in this initiative to assist other road authorities in their prospective undertakings related to SafetyAnalyst. This paper highlights challenges associated with compiling infrastructure data, traffic volume data, collision data, importing data into SafetyAnalyst while keeping the road authority's databases unchanged, Safety Performance Functions in SafetyAnalyst, and customized values for various modules in SafetyAnalyst. This paper provides solutions to address these challenges. It also recommends the necessary steps for road authorities before starting an initiative to configure SafetyAnalyst for their network.
Guo J.,Nanjing Southeast University |
Huang W.,Nanjing Southeast University |
Wei Y.,Nanjing Southeast University |
Zhang L.,Transportation Engineer
KSCE Journal of Civil Engineering | Year: 2013
Considering the importance of estimating speed from single loop detector measurements for many Intelligent Transportation System (ITS) related applications, a variety of algorithms have been developed in the literature for specific time intervals. However, the performance of these algorithms over a spectrum of time intervals has not yet received appropriate attention in the transportation research community. In this study, a Kalman filter based algorithm is selected as a typical representative and investigated over a spectrum of 30 time intervals starting from 1-minute to 30-minute with one minute increment. Empirical results using real world data show that the selected algorithm has workable performances for most of the time intervals under investigation. Specifically, the performances of the selected approach improve for intervals from 1-minute to 5-minute, stay stable for intervals between 5-minute and 15-minute, and decrease slightly for longer time intervals greater than 15-minute. The results demonstrate the ability of the selected algorithm to be readily implemented in a variety of transportation applications with specific time interval needs. Future work is recommended to develop a framework of coupling speed estimating algorithms and real world transportation applications through investigating other single loop speed estimation approaches and ITS application related time interval needs. © 2013 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg.
Selby B.,Transportation Engineer |
Kockelman K.M.,University of Texas at Austin
Journal of Transport Geography | Year: 2013
This work explores the application of two distinctive spatial methods for prediction of average daily traffic counts across the Texas network. Results based on Euclidean distances are compared to those using network distances, and both allow for strategic spatial interpolation of count values while controlling for each roadway's functional classification, lane count, speed limit, and other site attributes. Both universal kriging and geographically weighted regression (GWR) are found to reduce errors (in practically and statistically significant ways) over non-spatial regression techniques, though errors remain quite high at some sites, particularly those with low counts and/or in less measurement-dense areas. Nearly all tests indicated that the predictive capabilities of kriging exceed those of GWR by average absolute errors of 3-8%. Interestingly, the estimation of kriging parameters by network distances show no enhanced performance over Euclidean distances, which require less data and are much more easily computed. © 2012 Elsevier Ltd.
Zhang W.,Transportation Engineer |
Gkritza K.,Iowa State University |
Keren N.,Iowa State University |
Nambisan S.,Iowa State University
Journal of Safety Research | Year: 2011
Introduction: This paper investigates potential gender and age differences in conviction and crash occurrence subsequent to being directed to attend Iowa's Driver Improvement Program (DIP). Methods: Binary logit models were developed to investigate the factors that influence conviction occurrence after DIP by gender and age. Because of the low crash occurrence subsequent to DIP, association rules were applied to investigate the factors that influence crash occurrence subsequent to DIP, in lieu of econometric models. Results: There were statistical significant differences by driver gender, age, and conviction history in the likelihood of subsequent convictions. However, this paper found no association between DIP outcome, crash history, and crash occurrence. Impact on industry: Evaluating the differences in conviction and crash occurrence subsequent to DIP between female and male drivers, and among different age groups can lead to improvements of the effectiveness of DIPs and help to identify low-cost intervention measures, customized based on drivers' gender and age, for improving driving behaviors. © 2011 National Safety Council and Elsevier Ltd. All rights reserved.
News Article | November 16, 2016
International engineering consultancy Walter P Moore opened its 17th U.S. and 2nd Oklahoma office location in the state’s capital on November 1, 2016, and has appointed Senior Associate and Senior Transportation Engineer Brent Bolerjack, P.E. to lead the new office’s daily operations. The Oklahoma City office complements the previously established Tulsa location to provide expanded Transportation, Traffic, ITS, Water Resources, and Civil Engineering design services that better serve the firm’s growing list of clients statewide. Principal Hollis Allen, P.E. will serve as Managing Director for all of Walter P Moore’s Oklahoma operations. One of Oklahoma’s leading Bridge Inspection Program Managers, Brent joins Walter P Moore with 14+ years of experience as a project manager and designer on civil projects involving bridge and roadway design, mostly for state and local governments. Brent’s experience has also included overseeing the engineering and plan preparation for numerous Safe Routes to School projects scattered throughout Oklahoma. He also serves as a program manager for bridge inspection services throughout the state. For more information on Walter P Moore’s Oklahoma City office, see the firm’s website here. About Walter P Moore Walter P Moore is an international company of engineers, innovators, and creative people who solve some of the world’s most complex structural and infrastructure challenges. Providing structural, diagnostics, civil, traffic, parking, transportation, enclosure, and construction engineering services, they design solutions that are cost- and resource-efficient, forward-thinking, and help support and shape communities worldwide. Founded in 1931 and headquartered in Houston, Texas, Walter P Moore‘s 600+ professionals work across 17 U.S. offices and five international locations. Editor’s Note: There is no period after the ‘P’ in Walter P Moore.