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Author: Nicholas J. Garber Publisher: ISBN: Category : Traffic accidents Languages : en Pages : 38
Book Description
Although considerable progress has been made over the past several years in making highway travel safer, the frequency and severity of speed-related crashes on the nation's highways continue to be of concern. Understanding the factors associated with these crashes enables engineers to identify and implement effective countermeasures to reduce the probability of crashes. A number of studies have been conducted to determine the variation of crash rates as they relate to hourly traffic volumes, geometric characteristics, average speed, and speed variance. However, these studies have not established mathematical relationships that can be used to estimate changes in the crash characteristics as a result of the combined changes in speed, flow, and geometric characteristics. The establishment of direct mathematical models that describe the influence of these factors on crash characteristics would significantly enhance the efforts of traffic engineers to determine suitable countermeasures to reduce the occurrence and severity of crashes. This project develops mathematical relationships that describe the combined influence that traffic and geometric characteristics have on crash occurrences. This study was limited to roadways in the state of Virginia with speed limits of 89 or 105 km/h (55 or 65 mph). The data were obtained from speed monitoring stations established by the Virginia Department of Transportation (VDOT) and from police accident reports from January 1993 to September 1995. Using the variables of mean speed, standard deviation of speed, flow per lane, lane width, and shoulder width to predict crash rates, different types of deterministic models, such as multiple linear regression, robust regression, and multivariate ratio of polynomials were fitted to the data. The multivariate ratio of polynomials was found to be the only mathematical model type that was successful in describing any relationship between the combined effects of changes in the speed, flow, and geometric characteristics of the road on crash rates. Based on this study, all of the models show that under most traffic conditions, the crash rate tends to increase as the standard deviation of speed increases. The effect of the flow per lane and mean speed on the crash rate varied with respect to the type of highway.
Author: Nicholas J. Garber Publisher: ISBN: Category : Traffic accidents Languages : en Pages : 38
Book Description
Although considerable progress has been made over the past several years in making highway travel safer, the frequency and severity of speed-related crashes on the nation's highways continue to be of concern. Understanding the factors associated with these crashes enables engineers to identify and implement effective countermeasures to reduce the probability of crashes. A number of studies have been conducted to determine the variation of crash rates as they relate to hourly traffic volumes, geometric characteristics, average speed, and speed variance. However, these studies have not established mathematical relationships that can be used to estimate changes in the crash characteristics as a result of the combined changes in speed, flow, and geometric characteristics. The establishment of direct mathematical models that describe the influence of these factors on crash characteristics would significantly enhance the efforts of traffic engineers to determine suitable countermeasures to reduce the occurrence and severity of crashes. This project develops mathematical relationships that describe the combined influence that traffic and geometric characteristics have on crash occurrences. This study was limited to roadways in the state of Virginia with speed limits of 89 or 105 km/h (55 or 65 mph). The data were obtained from speed monitoring stations established by the Virginia Department of Transportation (VDOT) and from police accident reports from January 1993 to September 1995. Using the variables of mean speed, standard deviation of speed, flow per lane, lane width, and shoulder width to predict crash rates, different types of deterministic models, such as multiple linear regression, robust regression, and multivariate ratio of polynomials were fitted to the data. The multivariate ratio of polynomials was found to be the only mathematical model type that was successful in describing any relationship between the combined effects of changes in the speed, flow, and geometric characteristics of the road on crash rates. Based on this study, all of the models show that under most traffic conditions, the crash rate tends to increase as the standard deviation of speed increases. The effect of the flow per lane and mean speed on the crash rate varied with respect to the type of highway.
Author: Sungshin Kim Publisher: Springer ISBN: 3319055704 Category : Technology & Engineering Languages : en Pages : 102
Book Description
Nowadays, people have tendency to be fond of smarter machines that are able to collect data, make learning, recognize things, infer meanings, communicate with human and perform behaviors. Thus, we have built advanced intelligent control affecting all around societies; automotive, rail, aerospace, defense, energy, healthcare, telecoms and consumer electronics, finance, urbanization. Consequently, users and consumers can take new experiences through the intelligent control systems. We can reshape the technology world and provide new opportunities for industry and business, by offering cost-effective, sustainable and innovative business models. We will have to know how to create our own digital life. The intelligent control systems enable people to make complex applications, to implement system integration and to meet society’s demand for safety and security. This book aims at presenting the research results and solutions of applications in relevance with intelligent control systems. We propose to researchers and practitioners some methods to advance the intelligent controls and apply the intelligent control to specific or general purpose. This book consists of 10 contributions that feature an experimental verification of defect detections, depth-based visual object groupings, fuzzy-tuning PID controller, and control of traffic speed, robust object detection, and detection method of radio frequency interference, ontological model for the tax system, future toy web, cooperation level estimation, and interface for wearable computers. This edition is published in original, peer reviewed contributions covering from initial design to final prototypes and authorization.
Author: National Research Council (U.S.). Transportation Research Board Publisher: ISBN: Category : Traffic accidents Languages : en Pages : 148
Book Description
Transportation Research Record contains the following papers: Method for identifying factors contributing to driver-injury severity in traffic crashes (Chen, WH and Jovanis, PP); Crash- and injury-outcome multipliers (Kim, K); Guidelines for identification of hazardous highway curves (Persaud, B, Retting, RA and Lyon, C); Tools to identify safety issues for a corridor safety-improvement program (Breyer, JP); Prediction of risk of wet-pavement accidents : fuzzy logic model (Xiao, J, Kulakowski, BT and El-Gindy, M); Analysis of accident-reduction factors on California state highways (Hanley, KE, Gibby, AR and Ferrara, T); Injury effects of rollovers and events sequence in single-vehicle crashes (Krull, KA, Khattack, AJ and Council, FM); Analytical modeling of driver-guidance schemes with flow variability considerations (Kaysi, I and Ail, NH); Evaluating the effectiveness of Norway's speak out! road safety campaign : The logic of causal inference in road safety evaluation studies (Elvik, R); Effect of speed, flow, and geometric characteristics on crash frequency for two-lane highways (Garber, NJ and Ehrhart, AA); Development of a relational accident database management system for Mexican federal roads (Mendoza, A, Uribe, A, Gil, GZ and Mayoral, E); Estimating traffic accident rates while accounting for traffic-volume estimation error : a Gibbs sampling approach (Davis, GA); Accident prediction models with and without trend : application of the generalized estimating equations procedure (Lord, D and Persaud, BN); Examination of methods that adjust observed traffic volumes on a network (Kikuchi, S, Miljkovic, D and van Zuylen, HJ); Day-to-day travel-time trends and travel-time prediction form loop-detector data (Kwon, JK, Coifman, B and Bickel, P); Heuristic vehicle classification using inductive signatures on freeways (Sun, C and Ritchie, SG).
Author: National Research Council (U.S.). Transportation Research Board Publisher: ISBN: Category : Intelligent transportation systems Languages : en Pages : 176
Author: Nicholas J. Garber Publisher: ISBN: Category : Traffic accidents Languages : en Pages : 38
Book Description
A relationship between traffic flow variables and crash characteristics can greatly help the traffic engineer in the field to arrive at appropriate congestion mitigation measures that not only alleviate congestion and save time but also reduce the probability of crashes. Currently, no such decision support tool is readily available to traffic engineers who now mainly make vital decisions using their experience and intuition. This project investigated the feasibility of developing a methodology in which real-time data can be used to decide on diversion strategies that also consider crash risk. Models showing the interaction between flow and density (occupancy) and the relationship of these traffic flow parameters to crash characteristics were developed for specific sites in the Hampton Roads area of Virginia. These models were then used as the basis for developing a methodology that incorporates crash risk in identifying congestion strategies that consider crash risk. The results show that it is feasible to incorporate crash risk in developing congestion mitigation strategies. To use the methodology developed in this study, it is necessary to develop the appropriate models for each site that relate flow and occupancy and crashes and occupancy.
Author: Kenneth P. Drummond Publisher: ISBN: Category : Roads Languages : en Pages : 36
Book Description
One of the most controversial access management techniques practitioners face is also one of the most common: restricting signal density. Increased signal density can improve access for minor approaches to a corridor; however, it can also increase delays and rear-end crashes for vehicles on the mainline (major) approach. An ability to evaluate the impacts of increased signal spacing is thus critical for decision makers. Because crash data are not always easy to obtain, a logical question arises: Can simulation models be used to evaluate the safety impacts of increased traffic signal density? This report describes a method for using simulation models to evaluate the safety impacts of increased traffic signal density in suburban corridors. Using 10 years of data from two major arterials in Virginia, actual crash rates were compared with operational performance measures simulated by the Synchro/SimTraffic model. As expected, crash rates were positively correlated with stops per vehicle and delay per vehicle and negatively correlated with mainline speed. Three findings were significant. First, the correlation between crash rates and select mainline performance measures (delay, speed, and stops) was relatively strong despite the inherent variability in crash rates: R2, a measure of explained variance in crash rates, yielded values from 0.54 to 0.89. Second, three distinct regimes relate stops per vehicle to signal density: the installation of the first few signals causes a drastic increase in stops, the addition of the next set of signals causes a moderate increase in stops, and the addition of a third set of signals does not significantly affect the number of stops per vehicle. Third, multiple regime models also relate delay per vehicle to signal density. This study recommends two practical applications. To the extent these mainline performance measures correlate with crashes, simulation modeling may be used to estimate safety impacts of increased signals, which is appealing because simulation packages are becoming easier to apply. Further, three regime models can suggest when, in the timeline of corridor development, the addition of a traffic signal is likely to degrade corridor performance significantly versus when it will have little effect, thereby allowing decision makers to expend political capital when it is most beneficial (e.g., the occasions when there is significant degradation of corridor performance). Most important, the approach herein suggests a long-range corridor-planning tool for evaluating the impacts of different access densities.
Author: Nicholas J. Garber
Author: Nicholas J. Garber
Author: 
Author: Sungshin Kim
Author: R. Srinivasan
Author: 
Author: National Research Council (U.S.). Transportation Research Board
Author: National Research Council (U.S.). Transportation Research Board
Author: Nicholas J. Garber
Author: Kenneth P. Drummond
Author: