Prediction Of The Expected Safety Performance Of Rural Two Lane Highways

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Prediction Of The Expected Safety Performance Of Rural Two Lane Highways

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Author : Douglas W. Harwood
language : en
Publisher:
Release Date : 2000

Prediction Of The Expected Safety Performance Of Rural Two Lane Highways written by Douglas W. Harwood and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Low-volume roads categories.

This report presents an algorithm for predicting the safety performance of a rural two-lane highway. The accident prediction algorithm consists of base models and accident modification factors for both roadway segments and at-grade intersections on rural two-lane highways. The base models provide an estimate of the safety performance of a roadway or intersection for a set of assumed nominal or base conditions. The accident modification factors adjust the base model predictions to account for the effects on safety for roadway segments of lane width, shoulder width, shoulder type, horizontal curves, grades, driveway density, two-way left-turn lanes, passing lanes, roadside design and the effects on safety for at-grade intersections of skew angle, traffic control, exclusive left- and right-turn lanes, sight distance, and driveways. The accident prediction algorithm is intended for application by highway agencies to estimate the safety performance of an existing or proposed roadway. The algorithm can be used to compare the anticipated safety performance of two or more geometric alternatives for a proposed highway improvement. The accident prediction algorithm includes a calibration procedure that can be used to adapt the predicted results to the safety conditions encountered by any particular highway agency on rural two-lane highways. The algorithm also includes an Empirical Bayes procedure that can be applied to utilize the safety predictions provided by the algorithm together with actual site-specific accident history data.

Quaderns De Recerca

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Author :
language : en
Publisher:
Release Date : 2004

Quaderns De Recerca written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

Evaluation Of Interactive Highway Safety Design Model Crash Prediction Tools For Two Lane Rural Roads On Kansas Department Of Transportation Projects

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Author : Howard Lubliner
language : en
Publisher:
Release Date : 2014

Evaluation Of Interactive Highway Safety Design Model Crash Prediction Tools For Two Lane Rural Roads On Kansas Department Of Transportation Projects written by Howard Lubliner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Rural roads categories.

Development Of Safety Performance Functions For Two Lane Rural Highways In The State Of Ohio

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Author : Abdulrahman Khalid Faden
language : en
Publisher:
Release Date : 2020

Development Of Safety Performance Functions For Two Lane Rural Highways In The State Of Ohio written by Abdulrahman Khalid Faden and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.

The Highway Safety Manual (HSM), which is the guidance document for state departments of transportation (DOTs), was published in 2010, and one of its sections, called Part C of HSM, it involves the development of crash prediction methods. The goal of the predictive method is to develop and calibrate safety performance functions (SPFs). SPFs are mostly regression models that associate the expected number of crashes quantitatively with traffic exposure and geometric characteristics of the road. However, HSM's default prediction models are not suitable for all states or jurisdictions because each state and jurisdiction have different characteristics, such as terrain, driver behaviors, weather conditions, etc. Hence, the principal objective of this study is to develop a prediction method for producing Ohio-specific SPF models to use for rural two-lane highways in the state of Ohio. This study aims to create jurisdiction-specific SPFs for two-lane rural highway segments as the first study for this type of roadway facility in the state of Ohio. Highway geometric data for almost 40,067 segments that have 21,666.03 miles and 79,481 total crashes that occurred for 4 consecutive years (2012-2015) were obtained from the Highway Safety Information System (HSIS) to create these new models using negative binomial regression and the pruned forward selection method by adding the interaction terms via JMP Pro software. The most critical variables used for analyzing and creating the best models for the state of Ohio are average annual daily traffic (AADT), segment length, lane width, shoulder width, posted speed limit, presence of curves and grades, which were proven to be statistically significant in developing SPFs. Besides, the standard goodness-of-fit parameters were chosen to evaluate the regression models was AIC. Two models were created for rural two-lane, two-way road segments in the state of Ohio, which can be used to predict all crash types and fatal and injury crashes.

Prediction Of The Expected Safety Performance Of Rual Two Lane Highways

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Author :
language : en
Publisher:
Release Date : 2000

Prediction Of The Expected Safety Performance Of Rual Two Lane Highways written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with categories.

Geometric Design Consistency On High Speed Rural Two Lane Roadways

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Author : National Cooperative Highway Research Program
language : en
Publisher: Transportation Research Board
Release Date : 2003

Geometric Design Consistency On High Speed Rural Two Lane Roadways written by National Cooperative Highway Research Program and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Express highways categories.

Regional Considerations Of The Rocky Mountains And Plains Regions In Calibrating Safety Performance Function On Rural Two Lane Highwasy And Interstate Freeways

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Author : Rameshwor Chalise
language : en
Publisher:
Release Date : 2016

Regional Considerations Of The Rocky Mountains And Plains Regions In Calibrating Safety Performance Function On Rural Two Lane Highwasy And Interstate Freeways written by Rameshwor Chalise and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Low-volume roads categories.

The American Association of State Highway and Transportation Officials, AASHTO’s Highway Safety Manual (HSM) was first released in 2010 and is considered as a significant milestone in the advancement of the practice of road safety analysis. An extensive workforce spearheaded by the Transportation Research Board (TRB) Committee gave a result in the form of the first Highway Safety Manual in the United States. The HSM has already been proven as a great asset in traffic safety practice and also in research related to traffic safety since it bridges the gap between the state-of-the-art of research and practice. The HSM’s analytical tools and techniques help to quantify the traffic safety and help in evaluation as well as decision making in planning design, operation, and maintenance. There are a number of states and transportation authorities which are already using the HSM along with the AASHTO design guide. Although the HSM is the sole national source for quantitative evaluation of traffic safety, it has some limitations and there remains some room for improvement. Safety Performance Functions are statistical models to predict the expected number of crashes per year for a certain roadway facility as a function of traffic, and, in some cases, roadway characteristics, and weather conditions. Simple SPFs are mostly developed using Average Annual Daily Traffic (AADT) only while Full SPFs consider additional factors to traffic such as roadway geometry, driver characteristics, and weather conditions. Part C-Predictive Methods in the HSM includes the calibration procedure of SPFs as well as guidelines on how to calibrate jurisdiction-specific SPFs. The main limitation in the HSM Part C is that the Safety Performance Functions (SPFs) for different road facilities were developed using data from only few states in the United States. Thus the provided SPFs cannot adequately represent all states and regions since each of the states has a different geographical features, weather conditions, crash reporting thresholds, and demographic attributes. The main goal of this research is to apply and validate some of the HSM parts; Part C, to Wyoming specific conditions. In this thesis, Wyoming-specific SPFs were developed using crash data and traffic data from 2003 to 2013 for both total crashes and fatal and injury (F+I) crashes. All the rural two-lane two-way roadways and interstate freeways were considered in developing Wyoming-specific Simple SPFs, however, segments were chosen randomly from different parts of the state to develop Wyoming-specific Full SPFs. Negative Binomial (NB) model was used to develop SPFs for both interstate freeways and two-lane two-way roadways. Also, Zero-Inflated Poisson (ZIP) model was developed for two-lane two-way roadways and compared with the NB model. Statistical goodness-of-fit tests were performed on the calibrated models. The results were compared in order to assess the transferability of the HSM SPFs in Wyoming. It was found that the HSM SPFs cannot be applied directly in the state of Wyoming. While Simple SPFs under-estimated and over-estimated the number of crashes for different roadway segments and severity levels, Wyoming-specific Full SPFs provided more accurate and precise crash prediction.

A Speed Prediction Model For Rural Two Lane Highways

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Author : Christopher R. Bennett
language : en
Publisher:
Release Date : 1994

A Speed Prediction Model For Rural Two Lane Highways written by Christopher R. Bennett and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1994 with Speed categories.

Accident Mitigation Guide For Congested Rural Two Lane Highways

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Author : Kay Fitzpatrick
language : en
Publisher: Transportation Research Board
Release Date : 2000

Accident Mitigation Guide For Congested Rural Two Lane Highways written by Kay Fitzpatrick and has been published by Transportation Research Board this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Transportation categories.

Estimating The Safety Effects Of Horizontal Curves On Pennsylvania Two Lane Rural Roads

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Author : Jeffrey Gooch
language : en
Publisher:
Release Date : 2015

Estimating The Safety Effects Of Horizontal Curves On Pennsylvania Two Lane Rural Roads written by Jeffrey Gooch and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Rural roads categories.

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.