scholarly journals Validation and implication of segmentation on Empirical Bayes for highway safety studies

2007 ◽  
Author(s):  
R. R. Souleyrette ◽  
R. P. Haas ◽  
T. H. Maze
Keyword(s):  
Empirical Bayes ◽  
Highway Safety ◽  
Safety Studies

Safety Evaluation of Alternative Audible Lane Departure Warning Treatments in Reducing Traffic Crashes: An Empirical Bayes Observational Before–After Study

2018 ◽  
Vol 2672 (21) ◽  
pp. 30-40 ◽  
Author(s):  
Lingtao Wu ◽  
Srinivas R. Geedipally ◽  
Adam M. Pike
Keyword(s):  
Empirical Bayes ◽  
Safety Evaluation ◽  
Highway Safety ◽  
Warning Systems ◽  
Lane Departure Warning ◽  
Crash Data ◽  
Pavement Markings ◽  
Lane Departure ◽  
Run Off ◽  
Single Vehicle

Roadway departure crashes are a major contributor to traffic fatalities and injury. Rumble strips have been shown to be an effective countermeasure in reducing roadway departure crashes. However, some roadway situations, for instance, inadequate shoulder width or roadway surface depth, have limited the application of conventional milled or rolled in rumble strips. Alternative audible lane departure warning systems, including profile (audible) pavement markings and preformed rumble bars, are increasingly used to overcome the limitations that exist with the milled rumble strips. So far, the safety effectiveness of these alternative audible lane departure warning systems has not been extensively assessed. The main purpose of this paper is to examine the safety effect of installing profile pavement markings and preformed rumble bars. Specifically, this study developed crash modification factors for these treatments that quantify the effectiveness in reducing single-vehicle-run-off-road (SVROR) and opposite-direction (OD) crashes. Traffic, roadway, and crash data at the treated sites on 189 miles of rural two-lane highways in Texas were analyzed using an empirical Bayes (EB) before–after analysis method. Safety performance functions from the Highway Safety Manual and Texas Highway Safety Design Workbook were used in the EB analysis. The results revealed a 21.3% reduction in all SVROR and OD crashes, and 32.5% to 39.9% reduction in fatal and injury SVROR and OD crashes after installing profile pavement marking and preformed rumble bars.

Highway Safety Manual Calibration: Assessing Alternate Definitions of the Calibration Factor

2018 ◽  
Vol 2672 (30) ◽  
pp. 99-108 ◽  
Author(s):  
Mahdi Rajabi ◽  
Jennifer Harper Ogle ◽  
Patrick Gerard
Keyword(s):  
Goodness Of Fit ◽  
Prediction Models ◽  
Highway Safety ◽  
Calibration Factor ◽  
Crash Frequency ◽  
Calibration Process ◽  
Highway Safety Manual ◽  
Safety Performance Functions ◽  
Safety Studies ◽  
Using Data

The publication of the Highway Safety Manual (HSM) in 2010 established crash frequency prediction as the essential safety measure for safety studies. However, given that the models were developed using a single state’s data, the HSM recommends calibration of the prediction models using data from the jurisdiction where they will be applied. This calibration process has been conducted in several states and many questions have been raised as a result. This paper is intended to investigate different definitions and criteria for the calibration factors, and provide recommendations for practitioners on which definition to use. In addition to the calibration factors in the HSM and previously published definitions, two other calibration factor equations are proposed and compared using multiple goodness of fit measures. Whereas each definition may outperform others in certain measures, in this study, it is recommended to use the definition that maximizes the likelihood between predicted and observed crashes. The idea is to follow the same concept in both state-specific safety performance functions development and calibration process, which is maximizing the likelihood of predicted and observed crashes.

Development of Crash Reduction Factors: Methods, Problems, and Research Needs

2003 ◽  
Vol 1840 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Joan Shen ◽  
Albert Gan
Keyword(s):  
Empirical Bayes ◽  
Group Method ◽  
Research Needs ◽  
Regression To The Mean ◽  
Before And After ◽  
Safety Studies ◽  
Development Methods ◽  
Crash Reduction ◽  
Before And After Study ◽  
Reduction Factors

Crash reduction factors (CRFs) are used in highway safety studies to predict safety benefits due to reduced numbers of crashes. NCHRP Report 162 identified the need for the development of a national comprehensive set of CRFs for each state to evaluate safety improvements. However, this need has not been met. As a result, many states have developed their own CRFs or have adopted CRFs from other states. A synthesis of the CRF development methods, the associated problems, and the research needs are provided. The emphasis is placed on the before-and-after study method because it has been, and still is, the method of choice for CRF development. Three before-and-after study methods were introduced and reviewed: ( a) the simple before-and-after method, ( b) the before-and-after study with comparison group method, and ( c) the before-and-after study with the empirical Bayes method. The problems associated with the simple before-and-after studies, including regression to the mean, crash migration, maturation, and external causal factor, are discussed. Several research needs related to crash migration and general CRF development are also identified. The information presented in the synthesis will be useful to states that plan to develop or update their CRFs.

scholarly journals Engineering Solutions to Enhance Traffic Safety Performance on Two-Lane Highways

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Lina Wu ◽  
Jiangwei Chu ◽  
Yusheng Ci ◽  
Shumin Feng ◽  
Xingwang Liu
Keyword(s):  
Traffic Safety ◽  
Empirical Bayes ◽  
Practical Importance ◽  
Cost Effective ◽  
Highway Safety ◽  
Safety Performance ◽  
Highway Traffic ◽  
Research Attention ◽  
Research Perspectives ◽  
Sight Distance

Improving two-lane highway traffic safety conditions is of practical importance to the traffic system, which has attracted significant research attention within the last decade. Many cost-effective and proactive solutions such as low-cost treatments and roadway safety monitoring programs have been developed to enhance traffic safety performance under prevailing conditions. This study presents research perspectives achieved from the Highway Safety Enhancement Project (HSEP) that assessed safety performance on two-lane highways in Beijing, China. Potential causal factors are identified based on proposed evaluation criteria, and primary countermeasures are developed against inferior driving conditions such as sharp curves, heavy gradients, continuous downgrades, poor sight distance, and poor clear zones. Six cost-effective engineering solutions were specifically implemented to improve two-lane highway safety conditions, including (1) traffic sign replacement, (2) repainting pavement markings, (3) roadside barrier installation, (4) intersection channelization, (5) drainage optimization, and (6) sight distance improvement. The effectiveness of these solutions was examined and evaluated based on Empirical Bayes (EB) models. The results indicate that the proposed engineering solutions effectively improved traffic safety performance by significantly reducing crash occurrence risks and crash severities.

Estimating Safety by the Empirical Bayes Method: A Tutorial

2002 ◽  
Vol 1784 (1) ◽  
pp. 126-131 ◽  
Author(s):  
Ezra Hauer ◽  
Douglas W. Harwood ◽  
Forrest M. Council ◽  
Michael S. Griffith
Keyword(s):  
Professional Practice ◽  
Empirical Bayes ◽  
Highway Safety ◽  
Design Model ◽  
Bayes Method ◽  
Safety Improvement ◽  
Safety Design ◽  
Empirical Bayes Method ◽  
History Of ◽  
Safety Estimation

The empirical Bayes (EB) method addresses two problems of safety estimation: it increases the precision of estimates beyond what is possible when one is limited to the use of a 2- to 3-year accident history, and it corrects for the regression-to-mean bias. The increase in precision is important when the usual estimate is too imprecise to be useful. The elimination of the regression-to-mean bias is important whenever the accident history of the entity is in some way connected with the reason why its safety is estimated. The theory of the EB method is well developed. It is now used in the Interactive Highway Safety Design Model and will be used in the Comprehensive Highway Safety Improvement Model. The time has come for the EB method to be the standard and staple of professional practice. The study’s goal is to facilitate the transition from theory into practice.

Empirical-Bayes adjustment improved conventional estimates in postmarketing drug-safety studies

2006 ◽  
Vol 59 (11) ◽  
pp. 1162-1168 ◽  
Author(s):  
Vincenzo Bagnardi ◽  
Edoardo Botteri ◽  
Giovanni Corrao
Keyword(s):  
Drug Safety ◽  
Empirical Bayes ◽  
Safety Studies

The Use of the Fatal Accident Reporting System (FARS) in Evaluating Characteristics of Virginia Traffic Fatalities

1978 ◽  
Vol 22 (1) ◽  
pp. 640-643
Author(s):  
Deborah Mitchell ◽  
Cheryl Lynn
Keyword(s):  
Traffic Accidents ◽  
Reporting System ◽  
Highway Safety ◽  
Traffic Fatalities ◽  
Insufficient Information ◽  
Fatal Accident ◽  
System A ◽  
Safety Studies ◽  
Using Data ◽  
Age And Sex

Highway safety studies often involve a review of accident reports in order to determine those factors involved in traffic accidents. While this is a popular approach, It often entails problems resulting from incomplete information, contradictions in the available data, and difficulties in compiling information from various sources. For these reasons, the Fatal Accident Reporting System, a computerized data base, was chosen for use in evaluating the characteristics of Virginia traffic fatalities. In particular, the Fatal Accident Reporting System (FARS) was applied to investigate the reason for the increase in traffic fatalities in Virginia in 1977 and determining their characteristics. Using data from the FARS, fatal traffic accidents in Virginia during 1976 and 1977 were compared by examining demographic characteristics of the accidents such as day of week, type of road, kind of location, and the age and sex of the drivers involved. The data were examined according to three categories; 1) accident, 2) vehicle/driver, and 3) person. It was found, however, that for all levels of factors, some data were unusable because of problems in format, insufficient information, and apparent inconsistencies in coding. The system was not found to be easily accessible and was also comparativly expensive. For these reasons, it was concluded that use of the Fatal Accident Reporting System does not appear to be the best method of evaluating characteristics of Virginia traffic fatalities.

Maximum Output Intensity of the Audiokinetron

1996 ◽  
Vol 5 (2) ◽  
pp. 68-72 ◽  
Author(s):  
Christine M. Rankovic ◽  
William M. Rabinowitz ◽  
Gregory L. Lof
Keyword(s):  
Developmental Disabilities ◽  
Maximum Output ◽  
Output Intensity ◽  
Safety Studies ◽  
Auditory Integration Training ◽  
Auditory Integration

The Audiokinetron is a device that processes music for earphone presentation to patients undergoing auditory integration training, a treatment for individuals with autism and other developmental disabilities. Intensity levels produced by the Audiokinetron were measured under realistic listening conditions with a KEMAR manikin substituted for a patient. Average levels at the eardrum were 110 dB SPL when the device was adjusted to the highest setting employed by a local, trained AIT practitioner and 118 dB SPL at the maximum setting of the device. These levels are potentially harmful to hearing and warrant further safety studies of AIT instruments and protocols.

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