Regional Considerations Of The Rocky Mountains And Plains Regions In Calibrating Safety Performance Function On Rural Two Lane Highwasy And Interstate Freeways
DOWNLOAD
Download Regional Considerations Of The Rocky Mountains And Plains Regions In Calibrating Safety Performance Function On Rural Two Lane Highwasy And Interstate Freeways PDF/ePub or read online books in Mobi eBooks. Click Download or Read Online button to get Regional Considerations Of The Rocky Mountains And Plains Regions In Calibrating Safety Performance Function On Rural Two Lane Highwasy And Interstate Freeways book now. This website allows unlimited access to, at the time of writing, more than 1.5 million titles, including hundreds of thousands of titles in various foreign languages. If the content not found or just blank you must refresh this page
Regional Considerations Of The Rocky Mountains And Plains Regions In Calibrating Safety Performance Function On Rural Two Lane Highwasy And Interstate Freeways
DOWNLOAD
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.
Calibration Of The Highway Safety Manual Safety Performance Function And Development Of Jurisdiction Specific Models For Rural Two Lane Two Way Roads In Utah
DOWNLOAD
Author : Bradford Brimley
language : en
Publisher:
Release Date : 2011
Calibration Of The Highway Safety Manual Safety Performance Function And Development Of Jurisdiction Specific Models For Rural Two Lane Two Way Roads In Utah written by Bradford Brimley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
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.
Calibration Of The Highway Safety Manual Safety Performance Function And Development Of Jurisdiction Specific Models For Rural Two Lane Two Way Roads In Utah
DOWNLOAD
Author : Bradford Brimley
language : en
Publisher:
Release Date : 2011
Calibration Of The Highway Safety Manual Safety Performance Function And Development Of Jurisdiction Specific Models For Rural Two Lane Two Way Roads In Utah written by Bradford Brimley and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
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.
Two Lane Rural Highways Safety Performance Functions
DOWNLOAD
Author : Venky Shankar
language : en
Publisher:
Release Date : 2016
Two Lane Rural Highways Safety Performance Functions written by Venky Shankar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with Roads categories.
Prediction Of The Expected Safety Performance Of Rural Two Lane Highways
DOWNLOAD
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 Rural 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.
Calibration And Development Of Safety Performance Functions For Rural Highway Facilities In Idaho
DOWNLOAD
Author : Matthew C. Sipple
language : en
Publisher:
Release Date : 2014
Calibration And Development Of Safety Performance Functions For Rural Highway Facilities In Idaho written by Matthew C. Sipple and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with Highway Safety Manual categories.
As the reduction of highway fatalities continues to be a point of emphasis for the U.S. Department of Transportation, many state and local agencies have incorporated safety enhancements into planning, design, operations, and maintenance. In 2010, the American Association of State Highway and Transportation Officials (AASHTO) released the Highway Safety Manual (HSM) as a resource to include safety in decision making for transportation professionals. AASHTO developed general safety performance functions (SPF) to predict crash frequencies based on crash data from various jurisdictions, and suggested that agencies calibrate those SPFs to local crash data and/or develop jurisdiction-specific safety performance functions. At the request of the Idaho Transportation Department (ITD), calibration factors were generated to calibrate the HSM SPFs for rural two-lane, two-way highways and rural stop controlled intersections based on Idaho crash history. In addition, new statewide SPFs were developed for the same rural facilities.
Quaderns De Recerca
DOWNLOAD
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.
Gravel Roads
DOWNLOAD
Author : Ken Skorseth
language : en
Publisher:
Release Date : 2000
Gravel Roads written by Ken Skorseth and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Gravel roads categories.
The purpose of this manual is to provide clear and helpful information for maintaining gravel roads. Very little technical help is available to small agencies that are responsible for managing these roads. Gravel road maintenance has traditionally been "more of an art than a science" and very few formal standards exist. This manual contains guidelines to help answer the questions that arise concerning gravel road maintenance such as: What is enough surface crown? What is too much? What causes corrugation? The information is as nontechnical as possible without sacrificing clear guidelines and instructions on how to do the job right.
Assessing Safety Performance Of Roadway Characteristics In Rural And Urban Contexts
DOWNLOAD
Author : Meghna Chakraborty
language : en
Publisher:
Release Date : 2022
Assessing Safety Performance Of Roadway Characteristics In Rural And Urban Contexts written by Meghna Chakraborty and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with Electronic dissertations categories.
Evaluating the safety performance of roadway segments and intersections typically involves associating traffic crashes, injuries, and fatalities to various roadway and traffic characteristics, which typically vary broadly between rural and urban contexts. In rural areas, roadway geometric characteristics often play a critical role in the safety performance of a given roadway, while myriad other factors, including driveways and intersections, tend to have a greater influence on urban roadway safety. However, certain geometric aspects, such as the characteristics of the horizontal curvature and the impact of driveway land-use type have not been well-explored in prior roadway safety research. There has also been limited research on the safety performance for roadways of lower functional classifications, such as minor arterial and collector roadways, which comprise a substantial portion of the nationwide roadway network but are often designed to lower standards and possess driver and trip characteristics that typically differ from those of principal arterials. Therefore, assumptions made on the general effect of the predictor variables from typical safety performance functions may not apply to lower roadway classes. This research sought to explore those gaps in the roadway safety research domain. To accomplish this objective, roadway characteristics were collected along with traffic volume and crash data for greater than 13,000 miles of two-lane roadways in rural, urban, and suburban areas from across the state of Michigan for the period of 2011 through 2018. A series of safety performance functions were developed using a mixed-effects negative binomial modeling structure, which included fixed-effects and random-effects to account for the unobserved heterogeneity associated with varying design standards and site characteristics. The results indicated that driveway density significantly influences crash occurrence across all land-use categories for paved highways, although no impact was observed on unpaved roads. Commercial driveways possessed a stronger effect on crash occurrence than residential driveways or industrial driveways. In urban areas, posted speed limit had a significant positive association with crash frequency, and this effect increased when the speed limit exceeded 40 mph. The effect of speed limit was stronger on urban minor arterial segments (compared to collectors) and for fatal and injury crashes (compared to property damage only). This research also assessed the safety impacts associated with horizontal curve characteristics on rural highway segments, including curve type, curve direction, curve-approaching, curve-following, and inner-curve tangent distances, and curve design speed on rural two-lane undivided highways. Similar to prior research, curves with design speeds lower than the posted speed limit showed elevated crash occurrence. Most notably, compound and reverse curves were associated with greater crash occurrence compared to simple curves, with the greatest impact by the reverse curves. The increased approaching tangent distance for the simple curve or the first of a series of compound or reverse curves increased crash likelihood, perhaps due to the decreased driver expectancy for curvature with increasing tangent distance. However, increased inner-curve tangent distance was found to be associated with decreased crash occurrence. Lastly, the left-turning curves were found to be associated with greater crash occurrence than that on the right-turning curves.
Evaluating Safety Performance Of Rural County Highways Using Mixed Effects Negative Binomial Models
DOWNLOAD
Author : Steven York Stapleton
language : en
Publisher:
Release Date : 2021
Evaluating Safety Performance Of Rural County Highways Using Mixed Effects Negative Binomial Models written by Steven York Stapleton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Electronic dissertations categories.
Safety on rural highways continues to be a serious concern in the United States. While only 20 percent of the population live in rural areas, approximately one-half of motor vehicle fatalities occur on rural roadways, resulting in a rural fatal crash rate that is approximately double that of urban areas. In many states, most rural arterial highways are owned by the state department of transportation. However, several states, including Michigan, possess a large rural county highway network. For example, nearly 75 percent of the approximately 120,000 miles of public roadways in Michigan are owned by one of the 83 county road agencies across the state.County-owned highways typically possess characteristics that differ considerably from those owned by the state department of transportation, which limits the usefulness of safety performance functions (SPFs) and crash modification factors (CMFs) generated based on state highways, including those found in the Highway Safety Manual (HSM). Thus, assumptions made from models generated using data from state highways may not apply county highways due to differences in traffic, design, and maintenance. As a substantial proportion of rural crashes occur on county roads, identification of factors affecting safety performance on rural county roads is critical to support highway safety improvement programs and development of design standards.A cross-sectional safety performance analysis was performed for county highway segments and stop-controlled intersections throughout rural Michigan, including both federal aid and non-federal aid highways, as well as paved and unpaved road surfaces. SPFs were developed using mixed effects negative binomial regression to determine the safety effect of various design elements and site characteristics, including cross-sectional and geometric characteristics, which were included in the models as fixed effects. Random intercepts were incorporated into the models to account for unobserved heterogeneity between counties and between individual sites.One particularly noteworthy contribution of this research was to investigate the impacts of horizontal curvature on safety performance. Curve radii data extracted from the Michigan roadway shapefile allowed for the safety performance effects of decreasing curve design speed to be assessed in an incremental manner. Horizontal curves on paved county roads with design speeds below 40 mph experienced crash occurrence that was more than four times greater than segments without substandard curvature. On unpaved roadways, such curves experienced three times greater crash occurrence compared to segments without substandard curvature. Deer-related crashes, however, were shown to be fewer in frequency along horizontal curves.For stop-controlled intersections, skew angle was a variable of interest. At rural four-leg stop-controlled intersections, skew angles between 10 and 39 degrees were associated with increased crash frequency at intersections across all intersection classes. Skew had the greatest effect when the major road was county non-federal aid, where skew angles between 10 and 39 degrees experienced 60 percent more crashes than intersections without skew. Considering federal-aid intersections, the skew effect was diminished by approximately one-half.As expected, county-specific SPFs differed from models previously developed for state highways, including the SPFs included in the HSM. Generally speaking, at intersections, county highways were found to experience fewer crashes per unit of traffic volume than state highways, with county non-federal aid highways showing the lowest crash occurrence. County highway segments tend to have higher crash frequency than state roads. However, this is not the case at all traffic volumes, which further shows the need for county-specific safety performance models.