Linear and Nonlinear Safety Intervention Models

Recent research has advocated the use of linear intervention models developed within a hierarchical full Bayes context to conduct road safety evaluations. These models acknowledge that the effects of a safety treatment (intervention) do not occur instantaneously but are spread over future time periods. Despite the demonstrated advantages of such models, the manner in which the implemented countermeasures affect safety at the treated locations according to their novelty, direct effects, and indirect effects is not completely understood. A novel nonlinear intervention model was proposed to better understand how safety countermeasures work. To demonstrate the proposed model's capabilities, linear and nonlinear (Koyck) models were applied to estimate the effectiveness of the installation of shoulder rumble strips on a number of highway segments in the province of British Columbia, Canada. In addition to providing the best fit, the nonlinear Koyck model provided valuable insight into the effectiveness of shoulder rumble strips. This model showed an immediate 24.9% reduction of off-road-right collisions after 1 year that decreased with time and a 19.2% reduction in collisions as a result of permanent treatment. Overall, the findings from this study can have a significant impact on the economic evaluation of safety programs and countermeasures.

[1]  Kaan Ozbay,et al.  A comparative Full Bayesian before-and-after analysis and application to urban road safety countermeasures in New Jersey. , 2010, Accident; analysis and prevention.

[2]  Andrew Gelman,et al.  General methods for monitoring convergence of iterative simulations , 1998 .

[3]  G. Judge,et al.  The Theory and Practice of Econometrics (2nd ed.). , 1986 .

[4]  Alan Pankratz,et al.  Forecasting with Dynamic Regression Models: Pankratz/Forecasting , 1991 .

[5]  Bhagwant Persaud.  SAFETY MIGRATION, THE INFLUENCE OF TRAFFIC VOLUMES, AND OTHER ISSUES IN EVALUATING SAFETY EFFECTIVENESS--SOME FINDINGS ON CONVERSION OF INTERSECTIONS TO MULTIWAY STOP CONTROL , 1986 .

[6]  A. Aeron-Thomas,et al.  Red-light cameras for the prevention of road traffic crashes. , 2005, The Cochrane database of systematic reviews.

[7]  Bradley P. Carlin,et al.  Bayesian measures of model complexity and fit , 2002 .

[8]  E Y-C Cheng,et al.  APPLICATION AND EVALUATION OF RUMBLE STRIPS ON HIGHWAYS , 1994 .

[9]  Tarek Sayed,et al.  Full Bayes Approach to Before-and-After Safety Evaluation with Matched Comparisons: Case Study of Stop-Sign In-Fill Program , 2010 .

[10]  Tarek Sayed,et al.  Evaluating the Insurance Corporation of British Columbia Road-Safety Improvement Program , 2004 .

[11]  Bhagwant Persaud,et al.  Guidance on Design and Application of Rumble Strips , 2010 .

[12]  Tarek Sayed,et al.  Accident prediction models with random corridor parameters. , 2009, Accident; analysis and prevention.

[13]  Bhagwant Persaud,et al.  Validation of a Full Bayes methodology for observational before-after road safety studies and application to evaluation of rural signal conversions. , 2009, Accident; analysis and prevention.

[14]  R R Marvin,et al.  AN EVALUATION OF SHOULDER RUMBLE STRIPS IN MONTANA , 2003 .

[15]  Michael D. Pawlovich,et al.  Iowa's Experience with Road Diet Measures: Use of Bayesian Approach to Assess Impacts on Crash Frequencies and Crash Rates , 2006 .

[16]  Eun Sug Park,et al.  A fully Bayesian multivariate approach to before-after safety evaluation. , 2010, Accident; analysis and prevention.

[17]  E. Ziegel.  Introduction to the Theory and Practice of Econometrics , 1989 .

[18]  Paul P Jovanis,et al.  Bayesian Multivariate Poisson Lognormal Models for Crash Severity Modeling and Site Ranking , 2009 .

[19]  Wen Li,et al.  The choice of statistical models in road safety countermeasure effectiveness studies in Iowa. , 2008, Accident; analysis and prevention.

[20]  Gary A. Davis,et al.  Use of Propensity Score Matching Method and Hybrid Bayesian Method to Estimate Crash Modification Factors of Signal Installation , 2006 .

[21]  Michael S. Griffith,et al.  Estimating Safety Benefits of Shoulder Rumble Strips on Two-Lane Rural Highways in Minnesota , 2007 .

[22]  Ezra Hauer,et al.  Estimating Safety by the Empirical Bayes Method: A Tutorial , 2002 .

[23]  T. Research,et al.  Safety Evaluation of Rolled-In Continuous Shoulder Rumble Strips Installed on Freeways , 2022 .

[24]  William F. Guthrie.  Bayesian Statistical Modeling, 2nd edition , 2009 .

[25]  H. Guitton,et al.  Distributed Lags and Investment Analysis , 1955 .

[26]  Ezra Hauer,et al.  OBSERVATIONAL BEFORE-AFTER STUDIES IN ROAD SAFETY -- ESTIMATING THE EFFECT OF HIGHWAY AND TRAFFIC ENGINEERING MEASURES ON ROAD SAFETY , 1997 .

[27]  Tarek Sayed,et al.  Urban Arterial Accident Prediction Models with Spatial Effects , 2009 .

[28]  J. Hendrikz,et al.  Speed enforcement detection devices for preventing road traffic injuries. , 2006, The Cochrane database of systematic reviews.

[29]  Andrew Thomas,et al.  WinBUGS - A Bayesian modelling framework: Concepts, structure, and extensibility , 2000, Stat. Comput..

[30]  Tarek Sayed,et al.  Measuring direct and indirect treatment effects using safety performance intervention functions , 2012 .

[31]  John K Kruschke,et al.  Bayesian data analysis. , 2010, Wiley interdisciplinary reviews. Cognitive science.

[32]  Tarek Sayed,et al.  A method to account for outliers in the development of safety performance functions. , 2010, Accident; analysis and prevention.

[33]  John N. Ivan,et al.  Evaluation of Safety Benefits and Potential Crash Migration Due to Shoulder Rumble Strip Installation on Connecticut Freeways , 2005 .

[34]  Per Gårder,et al.  Safety Effect of Continuous Shoulder Rumble Strips on Rural Interstates in Maine , 2006 .

[35]  Tarek Sayed,et al.  A full Bayes multivariate intervention model with random parameters among matched pairs for before-after safety evaluation. , 2011, Accident; analysis and prevention.

[36]  Bhagwant Persaud,et al.  Comparison of empirical Bayes and full Bayes approaches for before-after road safety evaluations. , 2010, Accident; analysis and prevention.

[37]  K. El-Basyouny,et al.  Collision prediction models using multivariate Poisson-lognormal regression. , 2009, Accident; analysis and prevention.

[38]  Paul Damien,et al.  A multivariate Poisson-lognormal regression model for prediction of crash counts by severity, using Bayesian methods. , 2008, Accident; analysis and prevention.

[39]  Tarek Sayed,et al.  Measuring safety treatment effects using full Bayes non-linear safety performance intervention functions. , 2012, Accident; analysis and prevention.

[40]  M. A. Wincek.  Forecasting With Dynamic Regression Models , 1993 .

[41]  Rune Elvik,et al.  Sources of uncertainty in estimated benefits of road safety programmes. , 2010, Accident; analysis and prevention.

[42]  Tarek Sayed,et al.  Impact of Rumble Strips on Collision Reduction on Highways in British Columbia, Canada: Comprehensive Before-and-After Safety Study , 2010 .

[43]  Shashi S Nambisan,et al.  Evaluating the Effectiveness of Continuous Shoulder Rumble Strips in Reducing Single-Vehicle Ran-Off-Roadway Crashes in Nevada , 2007 .

[44]  Michael Pawlovich,et al.  FROM EMPIRICAL BAYES TO FULL BAYES: METHODS FOR ANALYZING TRAFFIC SAFETY DATA , 2004 .