Calibrating the Highway Safety Manual Predictive Methods for Oregon Rural State Highways PDF Download
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Author: Fei Xie
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Book Description
The first edition of the Highway Safety Manual (HSM) provides a quantitative approach to predict the safety of transportation facilities based on the recently developed scientific methods. This approach, known as the predictive method, was developed for several states in the United States. Due to differences in driver population, weather condition and other issues, the State of Oregon is expected to calibrate these predictive models before using them. By locality, the existing predictive methods can be divided into two parts: rural highway predictive method and urban highway predictive method. This thesis focuses on the calibration project for the rural predictive models. Therefore, in the first part of this thesis, the author will illustrate the calibration process and calibration results for the rural facility types, including rural two-lane, two-way roads and rural multilane highways. Also, after the calibration project, the author found a new calibration sample size estimation procedure which is more statistically reliable than the current HSM sample size determination process. This new statistical estimation method will be explained and recommended for future calibration projects.
Author: Fei Xie
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Book Description
The first edition of the Highway Safety Manual (HSM) provides a quantitative approach to predict the safety of transportation facilities based on the recently developed scientific methods. This approach, known as the predictive method, was developed for several states in the United States. Due to differences in driver population, weather condition and other issues, the State of Oregon is expected to calibrate these predictive models before using them. By locality, the existing predictive methods can be divided into two parts: rural highway predictive method and urban highway predictive method. This thesis focuses on the calibration project for the rural predictive models. Therefore, in the first part of this thesis, the author will illustrate the calibration process and calibration results for the rural facility types, including rural two-lane, two-way roads and rural multilane highways. Also, after the calibration project, the author found a new calibration sample size estimation procedure which is more statistically reliable than the current HSM sample size determination process. This new statistical estimation method will be explained and recommended for future calibration projects.
Author:
Publisher:
ISBN:
Category : Roads
Languages : en
Pages : 123
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Book Description
"TRB's Transportation Research Record: Journal of the Transportation Research Board, No. 2515, explores 15 papers related to statistical methods and highway safety performance, including: Multivariate Full Bayesian Hot Spot Identification and Ranking: New Technique; Modeling Crash Rates for a Mountainous Highway by Using Refined-Scale Panel Data; Exploring Piecewise Linear Effects of Crash Contributing Factors with a Novel Poisson-Mixed Multivariate Adaptive Regression Splines Model; Classification of Gaps at Uncontrolled Intersections and Midblock Crossings Using Support Vector Machines; Safety Impacts of a Statewide Centerline Rumble Strip Installation Program; Evaluation of the Safety Effectiveness of the Conversion of Two-Lane Roadways to Four-Lane Divided Roadways: Bayesian Versus Empirical Bayes; Is Horizontal Curvature a Significant Factor of Safety in Rural Multilane Highways?; Developing Calibration Factors for Crash Prediction Models with Consideration of Crash Recording Threshold Change; Empirical Bayes Before-After Study on Safety Effect of Narrow Pavement Widening Projects in Texas; Transferability and Calibration of Highway Safety Manual Performance Functions and Development of New Models for Urban Four-Lane Divided Roads in Riyadh, Saudi Arabia; Safety Analysis of Freeway Segments with Random Parameters; Strength of the Variable: Calculating and Evaluating Safety Performance Function Calibration Factors for the State of Ohio; Statistical Evaluation of Different Sample Sizes for Local Calibration Process in the Highway Safety Manual; Results and Lessons from Local Calibration Process of the Highway Safety Manual for the State of Maryland; Validation Technique Applied to Oregon Safety Performance Function Arterial Segment Models." -- Publisher's description
Author: Karen Dixon
Publisher: Transportation Research Board
ISBN: 0309213886
Category : Roads
Languages : en
Pages : 27
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Book Description
TRB’s National Cooperative Highway Research Program (NCHRP) Report 715: Highway Safety Manual Training Materials provides training materials to aid in implementing the American Association of State Highway and Transportation Officials’ Highway Safety Manual (HSM).
Author: Imalka Chiranthi Matarage
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Crash prediction models in the Highway Safety Manual (HSM) are used to quantify the safety experience of existing and new roadways. Safety performance functions (SPFs) or crash prediction models are statistical formulas developed on limited data from a few selected states, Kansas not being one of those states. Therefore, the HSM recommends calibration of HSM-default SPFs, or development of local SPFs, to enhance accuracy of predicted crash frequency. This dissertation demonstrates the HSM calibration procedure and its' quality assessment for freeway segments, speed-change lanes, ramp segments, and crossroad ramp terminals in Kansas. The study used three years of recent crash data, the most recent geometric data, and HSM-recommended sample sizes for all facilities considered for the calibration. The HSM methodology overpredicted all fatal and injury (FI) crashes and underpredicted all property damage only (PDO) crashes for freeway segments. The HSM methodology consistently underpredicted both FI and PDO crashes for both entrance- and exit-related speed-change lanes. The HSM methodology overpredicted all FI crashes, underpredicted multiple vehicle PDO crashes, and overpredicted single vehicle PDO crashes for entrance ramp segments. In the case of exit ramp segments, the HSM methodology underpredicted all multiple vehicle crashes and overpredicted all single vehicle crashes. The HSM methodology overpredicted all FI crashes and underpredicted all PDO crashes for both signal- and stop-controlled crossroad ramp terminals. Cumulative residual plots and coefficient of variation were used to evaluate the quality of calibrated HSM-default SPFs. Results of calibration quality assessment indicated that estimated calibration factors were satisfactory for all freeway and ramp facilities considered in this study. However, for further accuracy and comparison purposes, calibration functions were developed to improve the fit to local data. Calibration functions were better fitted compared to calibrated HSM-default SPFs for freeway and ramp facilities in Kansas. Challenges faced, how those challenges were addressed, and data collection techniques used in this study are discussed. In summary, estimated calibration factors and developed calibration functions of this study would greatly improve making accurate decisions related to freeway and ramp safety in Kansas.
Author: Adrian Colin Cameron
Publisher: Cambridge University Press
ISBN: 1107014166
Category : Business & Economics
Languages : en
Pages : 597
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Book Description
This book provides the most comprehensive and up-to-date account of regression methods to explain the frequency of events.
Author: Andrew Tarko
Publisher: Elsevier
ISBN: 0128105054
Category : Transportation
Languages : en
Pages : 254
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Book Description
Measuring Road Safety Using Surrogate Events provides researchers and practitioners with the tools they need to quickly and effectively measure traffic safety. As traditional crash-based safety analyses are being undermined by today’s growing use of intelligent vehicular and road safety technologies, crash surrogates--or near misses--can be more effectively used to measure the future risk of crashes. This book advances the idea of using these near-crash techniques to deliver quicker and more adequate measurements of safety. It explores the relationships between traffic conflicts and crashes using an extrapolation of observed events rather than post-crash data, which is significantly slower to obtain. Readers will find sound estimation methods based on rigorous scientific principles, offering compelling new tools to better equip researchers to understand road safety and its factors. Consolidates the latest updates/ideas from disparate places into a single resource Establishes a consistent use of key terms, definitions and concepts to help codify this emerging field Contains numerous application-oriented case studies throughout Includes learning aids, such as chapter objectives, a glossary, and links to data used in examples
Author: Grant G. Schultz
Publisher:
ISBN:
Category : Bayesian statistical decision theory
Languages : en
Pages : 72
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Book Description
This report documents the calibration of the Highway Safety Manual (HSM) safety performance function (SPF) for rural two-lane two-way roadway segments in Utah and the development of new models using negative binomial and hierarchical Bayesian modeling techniques. Crash data from 2005-2007 on 157 selected study segments in Utah provided a 3-year observed crash frequency to obtain a calibration factor for the HSM SPF and develop new models. The calibration factor for the HSM SPF for rural two-lane two-way roads in Utah is 1.16, indicating that the HSM underpredicts the number of crashes on these roads by 16 percent. Negative binomial regression was used to develop four new models, and one additional model was developed using hierarchical (or full) Bayesian techniques. The empirical Bayes (EB) method can be applied with each negative binomial model because the models include an overdispersion parameter used with the EB method. The hierarchical Bayesian technique accounts for high levels of uncertainty. Because the hierarchical Bayesian model produces a density function of a predicted crash frequency, a comparison of this density function with an observed crash frequency can help identify segments with significant safety concerns. Each model has its own strengths and weaknesses, which include its data requirements and predicting capability. This report recommends that UDOT use the negative binomial model with transformed average annual daily traffic (AADT) at a 95 percent confidence level (Equation 5-11) for predicting crashes. This model produces accurate results and requires less data than other models. The hierarchical Bayesian process should be used for identifying segments with extreme crash frequencies that may benefit from safety improvements.
Author: Bradford Brimley
Publisher:
ISBN:
Category :
Languages : en
Pages : 84
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Book Description
The study area was the state of Utah. Crash data from 2005-2007 on 157 selected study segments provided a 3-year observed crash frequency to obtain a calibration factor for the HSM SPF and develop new SPFs. The calibration factor for the HSM SPF for rural two-lane two-way roads in Utah is 1.16. This indicates that the HSM underpredicts the number of crashes on rural two-lane two-way roads in Utah by sixteen percent.
Author: Ezra Hauer
Publisher: Springer
ISBN: 9783319354460
Category : Technology & Engineering
Languages : en
Pages : 0
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Book Description
This unique book explains how to fashion useful regression models from commonly available data to erect models essential for evidence-based road safety management and research. Composed from techniques and best practices presented over many years of lectures and workshops, The Art of Regression Modeling in Road Safety illustrates that fruitful modeling cannot be done without substantive knowledge about the modeled phenomenon. Class-tested in courses and workshops across North America, the book is ideal for professionals, researchers, university professors, and graduate students with an interest in, or responsibilities related to, road safety. This book also: · Presents for the first time a powerful analytical tool for road safety researchers and practitioners · Includes problems and solutions in each chapter as well as data and spreadsheets for running models and PowerPoint presentation slides · Features pedagogy well-suited for graduate courses and workshops including problems, solutions, and PowerPoint presentations · Equips readers to perform all analyses on a spreadsheet without requiring mastery of complex and costly software · Emphasizes understanding without esoteric mathematics · Makes assumptions visible and explains their role and consequences
Author: Carlos Sun
Publisher:
ISBN:
Category : Traffic safety
Languages : en
Pages : 42
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Book Description
The Highway Safety Manual is the national safety manual that provides quantitative methods for analyzing highway safety. The HSM presents crash modification factors related to work zone characteristics such as work zone duration and length. These crash modification factors were based on high-impact work zones in California. Therefore there was a need to use work zone and safety data from the Midwest to calibrate these crash modification factors for use in the Midwest. Almost 11,000 Missouri freeway work zones were analyzed to derive a representative and stratified sample of 162 work zones. The 162 work zones was more than four times the number of work zones used in the HSM. This dataset was used for modeling and testing crash modification factors applicable to the Midwest. The dataset contained work zones ranging from 0.76 mile to 9.24 miles and with durations from 16 days to 590 days. A combined fatal/injury/non-injury model produced a R2 fit of 0.9079 and a prediction slope of 0.963. The resulting crash modification factors of 1.01 for duration and 0.58 for length were smaller than the values in the HSM. Two practical application examples illustrate the use of the crash modification factors for comparing alternate work zone setups.
