Modifying PIARC’s Linear Model of Accident Severity Index to Identify Roads' Accident Prone Spots to Rehabilitate Pavements Considering Nonlinear Effects of the Traffic Volume

Document Type: Technical Report


1 Member of Scientific Board of Road, Housing and Urban Development Centre (BHRC)

2 Department of Civil Engineering, Azad University, Tehran, Iran


Pavement rehabilitation could affect the accident severity index (ASI) since restoration measures means more safety for road users. No research or project has been carried out to identify hazard points to build a linear model based on crash severity index. One of the very popular accident severity index models used in all countries is based on linear models to rehabilitate pavements and this paper is aiming at correcting the deficiency of PIARC’s related model i.e. lack of sensitivity to changes in the traffic volume flow, to modify crash severity index (which is based on linear models) making an allowance for the nonlinear effects of traffic on eventful locations on dual carriageways. To do so, traffic volume has been chosen as the hazard criteria and, using multiple regression and statistical models, the coefficients and variables of the new model have been calculated by means of the SPSS software. This study presents the structural defects for the correction of linear models based on the accident severity (sensitive to changes in traffic volume). This research provides a linear model based on the crash severity index considering the nonlinear effects of the traffic volume to identify roads main eventful locations. Recommended that the model for a comprehensive database of accident data be built for all other roads in order to enhance the research accuracy.


Main Subjects

[1] Gourav Grewal, R. Bansal, V.K. Ahuja, (2015) “Study On Accident Severity Index, Time Of Accident And Vehicle Involved In Accident In Hisar City” International Journal of Enhanced Research in Science Technology & Engineering, ISSN: 2319-7463.

[2] Vivek V. Khanzodea, J. Maitib, P.K. Rayb (2012) “Occupational injury and accident research” A comprehensive review, ELSEVIER, , Pages 1355–1367.

[3] PIARC Road Safety Manual, (2011-2020) A manual for practitioners and decision makers on implementing safe system infrastructure, United Nations Decade of Action for Road Safety,

[4] Matthew G Karlaftis , Ioannis Golias (2002) “Effects of road geometry and traffic volumes on rural roadway accident rates”, ELSEVIER, Volume 34, Issue 3, May, Pages 357–365.

[5] Police Manual of Research and Information Technology (2011), (in Persian), Tehran and Mazandaran province.

[6] Mirzadeh, M. R., (2009), (in Persian), “The SPSS Statistical Analysis Software ", Taymaz Publishing, Printing Co.

[7] Rezaee Arjrudy. AR, Shabani, S (2007), (in Persian), Methods of Identification and Recording Accident-prone Sites, a Publication of Transportation Research Institute (TRI).

[8] Cerny, C.A., & Kaiser, H.F. (1977). A study of a measure of sampling adequacy for factor-analytic correlation matrices. Multivariate Behavioral Research, 12(1), 43-47.

[9] Kenneth J. White, “The Durbin-Watson (1992) Test for Autocorrelation in Nonlinear Models” Vol. 74, No. 2, pp. 370-373, Published by: The MIT Press,

[10] Steven L. Wise, (1990) Applied Statistics: Analysis of Variance and Regression by Olive Jean Dunn, Virginia A. Clark, Journal of Educational Statistics, Vol. 15, No. , pp. 175-178.