An Analysis of Vehicle Occupants’ Injury Severity in Crashes Occurred On Rural Freeways and Multilane Highways in Iran

Document Type : Research Paper


1 Assistant Professor, School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran, and Road Safety Research Centre, Iran University of Science and Technology, Tehran, Iran

2 Ph.D. Student, School of Civil Engineering, Iran University of Science and Technology and Road Safety Research Centre, Iran University of Science and Technology, Tehran, Iran


Vehicle occupants comprise a considerable proportion of traffic crash victims in Iran. This paper has focused on vehicle
occupants’ injury severity and employed the Classification and Regression Tree (CART) technique in order to
identify the most important variables affecting the injury severity of these road users in crashes occurred on rural freeways
and multilane highways in Iran over a three year period (2006-2008). In the procedure adopted in this paper, the
problem of three-class prediction was decomposed into four binary prediction models. Results revealed a high overall
prediction accuracy of the models. Ten explanatory variables were considered in the current study in order to find the
most important variables affecting the injury severity of occupants. In this regard, some “if-then” rules pertaining to
the conditions that lead to more severe injuries are provided based on the decision tree analysis. Results confirm the
already-known importance of seatbelt usage for preventing serious injuries in one hand, and imply the insufficiency
of seatbelt usage for protecting the occupants from receiving serious injuries in some collision types, on the other
hand. This underscores the need for more safety instruments (especially airbags for all occupants of the vehicle) to be
installed in passenger cars in Iran.


- Al-Ghadimi, A. S. (2002)“Using logistic regression to estimate the influence of accident factors on accident severity”. Accident Analysis and Prevention, Vol.34, No. 6, pp.729-741.
- Anarkooli, A. J. and Hosseinlou, M. H. (2016) ”Analysis  of the injury severity of crashes by considering different lighting conditions on two-lane rural roads”, Journal of Safety Research, Vol. 56, pp.57-65.
- Bédard, M., Guyatt, G. H., Stones, M. J. and Hirdes, J. P. (2002) “The independent contribution of driver, crash, and vehicle characteristics to driver fatalities”, Accident Analysis and Prevention, Vol. 34, No. 6, pp.717-727.
- Breiman, L., Friedman, J., Stone, C. J. and Olshen, R. A. (1984) “Classification and Regression Trees”, USA: CRC press.
- Chang, L.-Y. and Chen, W.-C. (2005a) “Data mining of tree-based models to analyze freeway accident frequency”, Journal of Safety Research, Vol. 36, pp. 365-375.
- Chang, L.-Y. and Chen, W.-C. (2005b) “Data mining of tree-based models to analyze freeway accident frequency”, Safety Research, Vol. 36, No. 4, pp. 365-375.
- Das, A. and Abdel-Aty, M. (2010). “A genetic programming approach to explore the crash severity on multi-lane roads”. Accident Analysis and Prevention, Vol. 42, No. 2, pp. 548-557.
- Delen, D., Sharda, R. and Bessonov, M. (2006) “Identifying significant predictors of injury severity in traffic ac cidents using a series of artificial neural networks”, Accident Analysis and Prevention, Vol. 38, No. 3, pp. 434-444.
- F.M.O.I. Forensic Medicine Organization of Iran (2012) “FMOI statistical data”, Accidents (in Farsi), Retrieved September 3, 2012, from http://www.lmo. ir/?siteid=1andpageid=1347
- Han, J. and Kamber, M. (2006). “Data Mining: Concepts and Techniques (2nd ed.)”. Elsevier.
- Milton, J. C., Shankar, V. N. and Mannering, F. L. (2008) “Highway accident severities and the mixed logit model: An exploratory empirical analysis”, Accident Analysis and Prevention, Vol. 40, No.1, pp. 260-266.
- Mirbaha, B., Saffarzadeh, M. and Noruzoliaee, M. H. (2012)” A model for predicting schoolchildren accidents in the vicinity of rural roads based on geometric design and traffic conditions”, International Journal of Transportation Engineering, Vol. 1, No. 1, pp. 25-33.
- Montella, A. (2011) “Identifying crash contributory factors at urban roundabouts and using association rules to explore their relationships to different crash types”, Accident Analysis and Prevention, Vol. 43, No.4, pp. 1451-1463.
- Mujalli, R. O. and De ONa, J. (2011) “A method for simplifying the analysis of traffic accidents injury severity on two-lane highways using Bayesian networks”, Journal of Safety Research, Vol. 42, No. 5, pp. 317-326.
- Pakgohar, A., Sigari Tabrizi, R., Khalili, M. and Esmaeili, A. (2011) “The role of human factor in incidence and severity of road crashes based on the CART and LR regression: a data mining approach”, Prosedia Computer Science, Vol. 3, pp. 764-769.
- Pham, H. (2006) “Handbook of engineering statistics”, Germany: Springer.
- Pour-Rouholamin, M. and Zhou, H. (2016) “Investigating the risk factors associated with pedestrian injury severity in Illinois”, Journal of Safety Research, Vol. 57, pp. 9-17.
- Iran Road Maintenance and Transportation Organization
- R.M.T.O (2015) “I.R. of Annual report (in Farsi) http://
- Savolainena, P. T., Mannering, F. L., Lord, D. and Quddus, M. A. (2011) “The statistical analysis of highway crash-injury severities: A review and assessment of methodological alternatives”, Accident Analysis and Prevention, Vol. 43, No. 5, pp. 1666-1676.
- Sohn, S. Y. and Shin, H. (2001) “Pattern recognition for road traffic accident severity in Korea”, Ergonomics, Vol. 44, No. 1, pp. 107-117.
- Steinberg, D. and Golovnya, M. (2007) “CART 6.0 User's Guide”, San Diego, California: Salford Systems.
- Tavakoli Kashani, A. and Besharati, M. M. (2016) “Fatality rate of pedestrians and fatal crash involvement rate of drivers in pedestrian crashes: a case study of Iran”, International Journal of Injury Control and Safety Promotion, pp. 1-10.
- Tavakoli Kashani, A., Rabieyan, R. and Besharati, M. M. (2015) “Modeling the effect of operator and passenger characteristics on the fatality risk of motorcycle crashes”, Journal of Injury And Violence Research, Vol. 8, No. 1.
- Tavakoli Kashani, A., Rabieyan, R. and Besharati, M. M. (2014) “A data mining approach to investigate the factors influencing the crash severity of motorcycle pillion passengers”, Journal of Safety Research, Vol. 51, pp. 93-98.
- Tavakoli Kashani, A., Shariat-Mohaymany, A. and Ranjbari, A. (2012) “Analysis of factors associated with traffic injury severity on rural roads in Iran”, Journal of Injury And Violence Research, Vol. 4, NO. 1, pp. 36.
- Valent, F., Schiava, F., Savonitto, C., Gallo, T., Brusaferro, S. and Barbone, F. (2002) “Risk factors for fatal road traffic accidents in Udine, Italy”, Accident Analysis and Prevention, Vol. 34, No. 1, pp. 71-84.
- Wood, D. P. and Simms, C. K. (2002) “Car size and injury risk: a model for injury risk in frontal collisions”, Accident Analysis and Prevention, 34, No.1, pp.93-99.