Determining Crash Modification Factor Resulted from Shoulder Safety by Creating a Crash Prediction Model by Empirical Bayes

Document Type : Original Article

Authors

1 Department of Civil Engineering‌, Payam Noor University(PNU), Tehran, Iran.

2 M.Sc., Grad., Department of Civil Engineering, Payam Noor University (PNU), Tehran, Iran.

10.22034/tri.2021.87445

Abstract

The shoulder width of the main roads has risen by 35% by revising the Highway Geometric Design. In this research, determination of the effect of simultaneously increasing shoulder width and its paving on decreasing crashes in rural two-way two-line highways was targeted. The studies were conducted in Ilam province highways and the experimental empirical Bayes (EB) method was used. Several highways sections with narrow shoulders paved or non-paved were selected as reference groups and crash data, traffic flow, and their geometry was collected and modeled. Three types of crash prediction model (SPF) were created for the total number of crashes, fatal crashes and shoulder related crashes in the cold seasons (autumn and winter) using the negative binomial regression model for the reference group. Some sections of which shoulders had become safety by widening and paving were also selected as an improved group. To estimate the crash modification factor (CMF), the expected crashes in all improved sections were summed up and then compared with the total number of observed crashes in the period after the countermeasure. The EB method was also repeated twice for the improved group of improving the narrow shoulder to the wide and paved shoulder. Once with the SPF for each of the three crash categories, considering the improved group may not be well-matched with the reference group, and once only with the SPF of the total crashes. The results showed that Widening and paving the shoulders affects considerably on the safety of the shoulders related crashes in the cold seasons with CMF of about 0.42 (58% reduction) and the fatal and injuring accidents with CMF of about 0.72 (28% reduction). It can also contribute to a 12 percent improvement of the total crashes of the cold seasons.

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References

-Abdi, A, Javadi, S, Fallah, A., (2018), “The Effect of Shoulder on Safety of Highways in Horizontal Curves: With Focus on Roll Angle”, KSCE Journal of Civil Engineering 22(8), pp.3153-3161.
-Darma, Y., Karim, M, R., and Abdullah, S., (2017), “An analysis of Malaysia road traffic death distribution by road environment”, Indian Academy of Sciences, Sadhana, Vol. 42, No. 9, September, pp. 1605–161.
-Gulati, H, Kumar, Er, N., (2017), “Impact of Roadway Condition, Traffic and Manmade Features on Road Safety”, International Research Journal of Engineering and Technology (IRJET), Vol. 04, November.
pp. 1011-1013.
-Hallmark, Shauna L., Hawkins, Neal., (2014), “Paved Shoulders, Iowa Department of Transportation Federal Highway Administration (In Trans Project 12-452), Tech Brief, October.
-Hauer, E., (1997), “Observational Before-After Studies in Road Safety. Pergamon Press”, Elsevier Science Ltd., Oxford, England.
-Harwood, D.W., F.M. Council, E. Hauer, W.E. Hughes, and A. Vogt., (2000), “Prediction of the Expected Safety Performance of Rural Two-Lane Highways”, Publication FHWA-RD-99-207, FHWA, U.S. Department of Transportation.
 
 
 
-Miaou, S.P., (1996), “Measuring the Goodness-of-Fit of Accident Prediction Models”, Publication FHWA-RD-96-040. FHWA, U.S. Department of Transportation.
-Mohan, D., Tiwari, G. and Bhalla, K., (2017), “Road Safety in India: Status Report New Delhi: Transportation Research & Injury Prevention Programme”, Indian Institute of Technology Delhi.
-Noland, R.B., M. A. Quddus, and W. Y. Ochieng, (2006), “The Effect of the Congestion Charge on Traffic Casualties in London: an Intervention Analysis”, Presented at 85th Annual meeting of the Transportation Research Board, Washington, D.C.
-Persaud, B., and C. A. Lyon., (2007), “Empirical Bayes Before-After Safety Studies: Lessons Learned from Two Decades of Experience and Future Directions”, Accident Analysis and Prevention, Vol. 39, No. 3, pp. 546-555.
-Quddus, M.A., (2008), “Time Series Count Data Models: An Empirical Application to Traffic Accidents”, Accident Analysis and Prevention, Vol. 40, No. 5, pp. 1732-1741.
-VicRoads Supplement to Austroads Guide to Road Design, (2017), Part 3 – Rev. 4.0.
-Vogt, J. and J.G. Bared, (1998), “Accident Models for Two-Lane Rural Roads: Segment and Intersections”, Report No. FHWA-RD-98-133. FHWA, U.S. Department of Transportation.
-Wooldridge, J. M., (2009), “Introductory Econometrics: A Modern Approach, Fourth Edition”, South-Western Cengage Learning, Inc., Mason, OH.
-Zeng, H., and S. D. Schrock, (2013), “Safety Effectiveness of Various Types of Shoulders on Rural Two-Lane Roads in winter and Non-Winter Periods”, Transportation Research Board 92nd Annual Meeting Compendium of Papers, Washington, DC.

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