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Author: Naveen Eluru
Publisher:
ISBN: 9780309709460
Category : Roads
Languages : en
Pages : 0
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Book Description
"Crash prediction analysis focuses on identifying attributes that result in traffic crashes and proposes effective countermeasures to improve the roadway design and operational attributes. These crash frequency models are typically employed for examining crash counts either at the micro- (intersection or segment) or the macro-level (county or traffic analysis zone).NCHRP Research Report 1103: The Effect of Vehicle Mix on Crash Frequency and Crash Severity, from TRB's National Cooperative Highway Research Program, aimed to develop methods to quantify the impact of vehicle mix on crash frequency and crash severity by facility type and develop a spreadsheet tool for practitioners to quantify the effect of vehicle mix on safety performance."--Publisher's website
Author: Naveen Eluru
Publisher:
ISBN: 9780309709460
Category : Roads
Languages : en
Pages : 0
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Book Description
"Crash prediction analysis focuses on identifying attributes that result in traffic crashes and proposes effective countermeasures to improve the roadway design and operational attributes. These crash frequency models are typically employed for examining crash counts either at the micro- (intersection or segment) or the macro-level (county or traffic analysis zone).NCHRP Research Report 1103: The Effect of Vehicle Mix on Crash Frequency and Crash Severity, from TRB's National Cooperative Highway Research Program, aimed to develop methods to quantify the impact of vehicle mix on crash frequency and crash severity by facility type and develop a spreadsheet tool for practitioners to quantify the effect of vehicle mix on safety performance."--Publisher's website
Author: Kristin Kersavage
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Reducing the number and severity of crashes on highways and streets is of high importance for government officials and transportation professionals in the United States. Substantial research has focused on various speed metrics, such as operating speeds and the posted speed limit, and their relationship to safety, such as crash frequency and crash severity. Crash severity is the safety measure most often linked to measures of speed and is based on dissipation of kinetic energy. However, many aspects of the relationships between speed metrics and crash frequency and risk have yet to be studied in depth, so a complete understanding of speeding-related crashes is unknown. Design speeds are used to establish geometric design criteria, and operating speed results from the geometric design process. Posted speed limits may be established based on operating speeds or by statute. When posted speed limits are inconsistent with design or operating speeds, road safety performance may be affected. A more complete understanding of the relationship between safety performance and operating speeds, posted speed limits, and design speeds may produce rational speed limits and lead to improved safety performance on roadways.This research combined real-time vehicle probe speed data, roadway inventory data, and crash data to assess crash risk and crash frequency.This thesis first determined the risk of a crash on two-lane rural highways based on operating speed metrics, differences between speed metrics, and traffic volume data. Results from the crash risk analysis indicate that operating speeds in 1-minute and 5-minute averages improve the statistical fit and prediction of binary logistic regression models. Higher traffic volumes and operating speeds higher than either the road average speed or road reference speed were associated with increased crash risk. Whereas, variations in travel speeds between vehicles were associated with decreased crash risk. This thesis also analyzed the frequency of crashes on horizontal curve segments of two-lane rural roadways using operating speed data, differences among speed metrics, traffic volume data, roadway inventory data, and crash data. Negative binomial regression models improve the statistical fit and prediction of crash frequency models compared to random-effects negative binomial regression. Generally, increases in the differences between operating speed and road average speed and the differences between operating speed and inferred design were associated with an increase in crash frequency. Increases in the differences between inferred design speed and posted speed limit were also associated with an expected increase in crash frequency; however, increases in the operating speed variance and in the difference between operating speeds and posted speed limit were associated with an expected decrease in crash frequency.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Previous analyses have indicated that mass reduction is associated with an increase in crash frequency (crashes per VMT), but a decrease in fatality or casualty risk once a crash has occurred, across all types of light-duty vehicles. These results are counter-intuitive: one would expect that lighter, and perhaps smaller, vehicles have better handling and shorter braking distances, and thus should be able to avoid crashes that heavier vehicles cannot. And one would expect that heavier vehicles would have lower risk once a crash has occurred than lighter vehicles. However, these trends occur under several alternative regression model specifications. This report tests whether these results continue to hold after accounting for crash severity, by excluding crashes that result in relatively minor damage to the vehicle(s) involved in the crash. Excluding non-severe crashes from the initial LBNL Phase 2 and simultaneous two-stage regression models for the most part has little effect on the unexpected relationships observed in the baseline regression models. This finding suggests that other subtle differences in vehicles and/or their drivers, or perhaps biases in the data reported in state crash databases, are causing the unexpected results from the regression models.
Author: National Research Council (U.S.). Transportation Research Board
Publisher:
ISBN:
Category : Traffic accidents
Languages : en
Pages : 148
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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: William Lee Carlson
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Author: Bhanu Sireesha Javvadi
Publisher:
ISBN:
Category : Traffic accidents
Languages : en
Pages : 150
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"This study examined the variables related to roadway geometry, environmental, driver and traffic factors to identify crash causal factors. It relied on three years of crash data from the Arkansas Highway Transportation Department (AHTD) and analyzed nonjunctions of rural and urban US highway systems. In the first part of this study, negative binomial modeling technique was used to model the frequency of crash occurrence. To further analyze the crash factors this study also analyzed crash severity and collision types. The second part identified the factors responsible for severe crashes and fatalities including using the binary logistic regression modeling technique. The third part used the multinomial logistic regression modeling technique to identify the factors associated with specific collision types (single vehicle, head-on, rear-end, sideswipe-same, and sideswipe-opposite direction). The crash data were analyzed statistically, and the factors significant for crash frequency proved to be surface width, roughness, left and right shoulder widths, road segment length, and Annual Average Daily Traffic. Driver related factors such as age, gender, restraint type, and alcohol consumption were significant in severe crashes. Variables such as horizontal and vertical road curvature, wet road surface, and darkness differentiated single-vehicle collisions from multi-vehicle collisions. This study clearly indicated the importance of using different analysis techniques to identify the main factors responsible for crashes"--Abstract, leaf iii.
Author: John R. Campbell
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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Author: Gaurav Satish Mehta
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 158
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Providing safe travel from one point to another is the main objective of any public transportation agency. The recent publication of the Highway Safety Manual (HSM) has resulted in an increasing emphasis on the safety performance of specific roadway facilities. The HSM provides tools such as crash prediction models that can be used to make informed decisions. The manual is a good starting point for transportation agencies interested in improving roadway safety in their states. However, the models published in the manual need calibration to account for the local driver behavior and jurisdictional changes. The method provided in the HSM for calibrating crash prediction models is not scientific and has been proved inefficient by several studies. To overcome this limitation this study proposes two alternatives. Firstly, a new method is proposed for calibrating the crash prediction models using negative binomial regression. Secondly, this study investigates new forms of state-specific Safety Performance Function SPFs using negative binomial techniques. The HSM's 1st edition provides a multiplier applied to the univariate crash prediction models to estimate the expected number of crashes for different crash severities. It does not consider the distinct effect unobserved heterogeneity might have on crash severities. To address this limitation, this study developed a multivariate extension of the Conway Maxwell Poisson distribution for predicting crashes. This study gives the statistical properties and the parameter estimation algorithm for the distribution. The last part of this dissertation extends the use of Highway Safety Manual by developing a multivariate crash prediction model for the bridge section of the roads. The study then compares the performance of the newly proposed multivariate Conway Maxwell Poisson (MVCMP) model with the multivariate Poisson Lognormal, univariate Conway Maxwell Poisson (UCMP) and univariate Poisson Lognormal model for different crash severities. This example will help transportation researchers in applying the model correctly.
Author:
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 140
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Author: A. M. Hasibul Islam
Publisher:
ISBN:
Category :
Languages : en
Pages : 53
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