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Author : Cyrus Safdari
Publisher :
ISBN 13 :
Total Pages : 280 pages
Book Rating : 4.3/5 (129 download)
Download or read book Analysis of Crash Rates on Horizontal Curves written by Cyrus Safdari and published by . This book was released on 1999 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Hojr Momeni
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (956 download)
Download or read book Identifying Effective Geometric and Traffic Factors to Predict Crashes at Horizontal Curve Sections written by Hojr Momeni and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Driver workload increases on horizontal curves due to more complicated navigation compared to navigation on straight roadway sections. Although only a small portion of roadways are horizontal curve sections, approximately 25% of all fatal highway crashes occur at horizontal curve sections. According to the Fatality Analysis Reporting System (FARS) database, fatalities associated with horizontal curves were more than 25% during last years from 2008 to 2014, reinforcing that investigation of horizontal curve crashes and corresponding safety improvements are crucial study topics within the field of transportation safety. Improved safety of horizontal curve sections of rural transportation networks can contribute to reduced crash severities and frequencies. Statistical methods can be utilized to develop crash prediction models in order to estimate crashes at horizontal curves and identify contributing factors to crash occurrences, thereby correlating to the primary objectives of this research project. Primary data analysis for 221 randomly selected horizontal curves on undivided two-lane two-way highways with Poisson regression method revealed that annual average daily traffic (AADT), heavy vehicle percentage, degree of curvature, and difference between posted and advisory speeds affect crash occurrence at horizontal curves. The data, however, were relatively overdispersed, so the negative binomial (NB) regression method was utilized. Results indicated that AADT, heavy vehicle percentage, degree of curvature, and long tangent length significantly affect crash occurrence at horizontal curve sections. A new dataset consisted of geometric and traffic data of 5,334 horizontal curves on the entire state transportation network including undivided and divided highways provided by Kansas Department of Transportation (KDOT) Traffic Safety Section as well as crash data from the Kansas Crash and Analysis Reporting System (KCARS) database were used to analyze the single vehicle (SV) crashes. An R software package was used to write a code and combine required information from aforementioned databases and create the dataset for 5,334 horizontal curves on the entire state transportation network. Eighty percent of crashes including 4,267 horizontal curves were randomly selected for data analysis and remaining 20% horizontal curves (1,067 curves) were used for data validation. Since the results of the Poisson regression model showed overdispersion of crash data and many horizontal curves had zero crashes during the study period from 2010 to 2014, NB, zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) methods were used for data analysis. Total number of crashes and severe crashes were analyzed with the selected methods. Results of data analysis revealed that AADT, heavy vehicle percentage, curve length, degree of curvature, posted speed, difference between posted and advisory speed, and international roughness index influenced single vehicle crashes at 4,267 randomly selected horizontal curves for data analysis. Also, AADT, degree of curvature, heavy vehicle percentage, posted speed, being a divided roadway, difference between posted and advisory speeds, and shoulder width significantly influenced severe crash occurrence at selected horizontal curves. The goodness-of-fit criteria showed that the ZINB model more accurately predicted crash numbers for all crash groups at the selected horizontal curve sections. A total of 1,067 horizontal curves were used for data validation, and the observed and predicted crashes were compared for all crash groups and data analysis methods. Results of data validation showed that ZINB models for total crashes and severe crashes more accurately predicted crashes at horizontal curves. This study also investigated the effect of speed limit change on horizontal curve crashes on K-5 highway in Leavenworth County, Kansas. A statistical t-test proved that crash data from years 2006 to 2012 showed only significant reduction in equivalent property damage only (EPDO) crash rate for adverse weather condition at 5% significance level due to speed limit reduction in June 2009. However, the changes in vehicles speeds after speed limit change and other information such as changes in surface pavement condition were not available. According to the results of data analysis for 221 selected horizontal curves on undivided two-lane highways, tangent section length significantly influenced total number of crashes. Therefore, providing more information about upcoming changes in horizontal alignment of the roadway via doubling up warning sings, using bigger sings, using materials with higher retroreflectivity, or flashing beacons were recommended for horizontal curves with long tangent section lengths and high number of crashes. Also, presence of rumble strips and wider shoulders significantly and negatively influenced severe SV crashes at horizontal curve sections; therefore, implementing rumble strips and widening shoulders for horizontal curves with high number of severe SV crashes were recommended.
Author : Hojr Momeni
Publisher :
ISBN 13 :
Total Pages : 72 pages
Book Rating : 4.:/5 (98 download)
Download or read book A Study to Mitigate Rural High-speed Horizontal Curve Crashes in Kansas written by Hojr Momeni and published by . This book was released on 2015 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: Driving on horizontal curves is a more complicated task than on straight sections of a roadway, and poses more workload on drivers as well. While a small portion of roadways are made up of horizontal curve sections, approximately a quarter of all fatal crashes on highways occur at horizontal curve sections. Thus, studying the crashes at horizontal curves and the safety improvement at these sections is one of the most interesting topics in the transportation safety field. Safety improvement of horizontal curve sections of rural transportation networks can effectively and considerably contribute to crash severity and frequency reduction. Low-cost countermeasures to improve traffic safety of horizontal curve sections and their effectiveness were discussed. A Kansas Department of Transportation (KDOT) crash database of nine years (from 2004 to 2012) was used and counties with high number of crashes were selected. Eleven counties with high number of horizontal curve related crashes were selected, and implemented countermeasures at the selected curves were investigated and discussed. K-5 highway is one of the highways with high number of crashes in which the speed limit of a long distance of the roadway, including the problematic curves, reduced in June 2009 from 55 miles per hour (mph) to 50 mph. The effect of this speed limit reduction on crash occurrences of seven years, including 3.5 years before and 3.5 years after the speed limit reduction, was investigated using a statistical t-test method. In addition, various countermeasures to improve the traffic safety of these horizontal curves were discussed.
Author : Jeffrey Gooch
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (915 download)
Download or read book Estimating the Safety Effects of Horizontal Curves on Pennsylvania Two-lane Rural Roads written by Jeffrey Gooch and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Roadway departure crashes are three times more likely on horizontal curves than on tangent sections of two-lane rural highways. Research is needed to better quantify the safety performance (e.g., crash frequencies) of these crash-prone locations. Existing safety performance functions (SPFs) for two-way rural highways in the Highway Safety Manual (HSM) rely on base conditions that assume all roadway segments are tangent sections. The resulting predictions of crash frequency are then modified using a crash modification factor (CMF) that includes as independent variables the curve length, curve radius and presence of a spiral transition. Unfortunately, the CMF in the HSM does not have a standard error associated with it, which greatly limits its practical application and provides no indication of the level of uncertainty associated with the CMF. Other existing CMFs for horizontal curves in the FHWA CMF Clearinghouse also suffer from a lack of standard error and dated statistical methods, resulting in low to average star quality ratings (three or less). Furthermore, these existing CMFs treat individual curves as isolated geometric elements, even though recent research has shown that the safety performance of a horizontal curve is significantly influenced by its proximity to neighboring curves. Curves in close proximity to each other are expected to have lower crash frequency than those that are isolated because they are less likely to violate driver expectation. Failure to account for this distance may lead to erroneous predictions of crash frequency on horizontal curves.The objective of this study is to develop a high-quality CMF for horizontal curves on two-lane rural roads that takes into consideration the proximity of neighboring geometric elements using the most statistically rigorous modeling technique available, which reduces the potential for bias in the estimate of the CMF and provides a standard error that can be used to estimate the CMF uncertainty. This CMF is estimated using eight years of crash data (2005-2012) obtained from over 10,000 miles of state-owned two-lane rural roads in Pennsylvania. This comprehensive data includes information on roadway geometry (e.g., horizontal curvature, lane width, and shoulder width), traffic volume, access density, roadside hazard rating, and the presence of various low-cost safety countermeasures (e.g., centerline and shoulder rumble strips, curve and intersection warning pavement markings, and aggressive driving pavement dots). The propensity scores-potential outcomes method is applied, which matches each horizontal curve with tangent sections that are similar with respect to all other site characteristics (excluding crash frequency). The propensity scores are estimated using binary logistic regression, and curves and tangents are matched based on the propensity scores using the nearest neighbor matching technique with calipers and without replacement. Matching is performed across county lines to avoid individual horizontal curves being matched with its neighboring upstream or downstream tangent sections, which are likely to have very similar features and endogenous effects. Crash prediction is performed by means of random effects and mixed negative binomial regression using the explanatory variables mentioned above as well as distance to adjacent horizontal curves. The results indicate that degree of curvature, curve length, and traffic volume must be considered when predicting the frequency of total and fatal and injury crashes on horizontal curves. The presence of a horizontal curve and degree of curvature increase crash frequency, while the length of curve and traffic volumes decrease expected crash frequency. These results were consistent for both random and mixed effects models. The impact of the distance to adjacent curves was not found to be statistically significant. When predicting fixed object crashes, a proxy for roadway departure crashes, only degree of curvature and the presence of a horizontal curve were found to be statistically significant. All crash modification estimates for degree of curvature were consistent with the existing literature. The crash modification functions estimated are supplemented with formulas to estimate a conservative value for the standard error of the resulting CMF. The resulting crash modification functions in this thesis are recommended to evaluate safety at rural two-lane horizontal curves in Pennsylvania.
Author : Raghavan Srinivasan
Publisher :
ISBN 13 :
Total Pages : 8 pages
Book Rating : 4.:/5 (11 download)
Download or read book Safety Evaluation of Horizontal Curve Realignment on Rural Two-lane Roads written by Raghavan Srinivasan and published by . This book was released on 2017 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technical brief on evaluated realignment of horizontal curves on rural two-lane roads based on before-after evaluations to reduce lane departure crashes, especially run-off-road crashes.
Author : King K. Mak
Publisher : Transportation Research Board
ISBN 13 : 0309068126
Total Pages : 77 pages
Book Rating : 4.3/5 (9 download)
Download or read book Roadside Safety Analysis Program (RSAP) written by King K. Mak and published by Transportation Research Board. This book was released on 2003 with total page 77 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : James A. Bonneson
Publisher : Transportation Research Board
ISBN 13 : 9780309066235
Total Pages : 180 pages
Book Rating : 4.0/5 (662 download)
Download or read book Superelevation Distribution Methods and Transition Designs written by James A. Bonneson and published by Transportation Research Board. This book was released on 2000 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 24 pages
Book Rating : 4.3/5 (91 download)
Download or read book Safety Effectiveness of Highway Design Features written by and published by . This book was released on 1992 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Research Council (U.S.). Transportation Research Board
Publisher :
ISBN 13 :
Total Pages : 136 pages
Book Rating : 4.:/5 (318 download)
Download or read book Design Speed, Operating Speed, and Sight Distance Issues written by National Research Council (U.S.). Transportation Research Board and published by . This book was released on 2000 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transportation Research Record contains the following papers: New stopping sight distance model for use in highway geometric design (Fambro, DB, Fitzpatrick, K and Koppa, R); Driver braking performance in stopping sight distance situations (Fambro, DB, Koppa, RJ, Picha, DL and Fitzpatrick, K); Safety effects of limited stopping sight distance on crest vertical curves (Fitzpatrick, K, Fambro, DB and Stoddard, AM); Operating speed on crest vertical curves with limited stopping sight distance (Fambro, DB, Fitzpatrick, K and Russell, CW); Sight distance for stop-controlled intersections based on gap acceptance (Harwood, DW, Mason, JM and Brydia, RE); Reliability approach to intersection sight distance design (Easa, SM), Evaluation of the passing process on two-lance rural highways (Polus, A, Livneh, M and Frischer, B); Determining the best method for measuring no-passing zones (Brown, RL and Hummer, JE); Design speed and operating speed in rural highway alignment design (Krammes, RA); Speed-profile model for a design-consistency evaluation procedure in the United States (Ottesen, JL and Krammes, RA); Speed reduction as a surrogate for accident experience at horizontal curves on rural two-lane highways (Anderson, IB and Krammas, RA); Geometric design of low-speed urban streets (Tarris, JP, Mason, JM and Antonucci, ND); Mathematical models of vehicular speed on mountain roads (Andueza, PJ); Truck speed profiles (Bester, CJ); Summary of design speed, operating speed, and design consistency issues (Harwood, DW, Neuman, TR and Leisch, JP).
Author : National Research Council (U.S.). Transportation Research Board
Publisher :
ISBN 13 :
Total Pages : 148 pages
Book Rating : 4.X/5 (4 download)
Download or read book Highway and Traffic Safety written by National Research Council (U.S.). Transportation Research Board and published by . This book was released on 2000 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : Kristin Kersavage
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Relationship Between Speed Metrics and Crash Frequency and Severity written by Kristin Kersavage and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : AASHTO
ISBN 13 : 1560514280
Total Pages : 87 pages
Book Rating : 4.5/5 (65 download)
Download or read book Guide for Pavement Friction written by and published by AASHTO. This book was released on 2008 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report contains guidelines and recommendations for managing and designing for friction on highway pavements. The contents of this report will be of interest to highway materials, construction, pavement management, safety, design, and research engineers, as well as others concerned with the friction and related surface characteristics of highway pavements.
Author : National Research Council (U.S.). Transportation Research Board
Publisher :
ISBN 13 :
Total Pages : 224 pages
Book Rating : 4.X/5 (4 download)
Download or read book Statistical Methods and Safety Data Analysis and Evaluation written by National Research Council (U.S.). Transportation Research Board and published by . This book was released on 2004 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Kay Fitzpatrick
Publisher :
ISBN 13 :
Total Pages : 150 pages
Book Rating : 4.:/5 (318 download)
Download or read book Recent Geometric Design Research for Improved Safety and Operations written by Kay Fitzpatrick and published by . This book was released on 2001 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 299: Recent Geometric Design Research for Improved Safety and Operations reviews and summarizes selected geometric design research published during the 1990s, particularly research with improved safety and operations implication.
Author : King K. Mak
Publisher :
ISBN 13 :
Total Pages : 230 pages
Book Rating : 4.3/5 (555 download)
Download or read book Accident Analysis: Technical report written by King K. Mak and published by . This book was released on 1980 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Douglas W. Harwood
Publisher :
ISBN 13 :
Total Pages : 100 pages
Book Rating : 4.E/5 ( download)
Download or read book Factors Contributing to Median Encroachments and Cross-median Crashes written by Douglas W. Harwood and published by . This book was released on 2014 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: "TRB's National Cooperative Highway Research Program (NCHRP) Report 790: Factors Contributing to Median Encroachments and Cross-Median Crashes investigates the factors that contribute to median-related crashes and identifies design treatments and countermeasures that can be applied to improve median safety on divided highways."--Publisher description.
Author : Tom V. Mathew
Publisher : Springer Nature
ISBN 13 : 9813290420
Total Pages : 905 pages
Book Rating : 4.8/5 (132 download)
Download or read book Transportation Research written by Tom V. Mathew and published by Springer Nature. This book was released on 2019-10-24 with total page 905 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents selected papers from the 4th Conference of the Transportation Research Group of India. It provides a comprehensive analysis of themes spanning the field of transportation encompassing economics, financial management, social equity, green technologies, operations research, big data analysis, econometrics and structural mechanics. This volume will be of interest to researchers, educators, practitioners, managers, and policy-makers world-wide.
