Evaluating the Relationship between Operating Speed and Collision Frequency of Rural Multilane Highways Based on Geometric and Roadside Features

Behzad Bamdad Mehrabani, Babak Mirbaha


Speed is one of the main functional factors that affect road safety in terms of both collision occurrence and collision severity. Previous studies have shown that several roadside and geometric features affect road safety and operating speed. This paper aims to evaluate the effects of roadside and geometric features on operating speed and collision frequency, simultaneously. For this purpose, the operating speed data of 103 segments along with their accident data and roadside and geometric characteristics were collected. Structural equation modelling (SEM) with latent variables was employed to model operating speed and collision frequency, simultaneously. Two latent variables including “geometric effect” and “roadside effect” were defined in SEM. The first latent variable is the combination of the natural logarithm of the segment length, longitudinal slope, the presence of a 2-meter paved shoulder, and curvature of the segment. The indicators of the second latent variable are the number of accesses and the presence of residential land use. The results show that the latent variable “roadside effect” increases collision frequency by a standard regression weight of 3.455; however, it reduces operating speed by a standard regression weight of –0.385. Also, the latent variable “geometric effect” causes an opposite effect on collision frequency and operating speed by the standard regression weight of –5.313 and 0.730, respectively. Besides, lower operating speed causes a reduction in the collision frequency by the standard regression weight of 7.734. The results of this study can be useful for designers and road safety agencies to improve road safety.


Operating Speed; Collision Frequency; Geometric Features; Roadside Features; Structural Equation Modeling.


Elvik, Rune, Peter Christensen, and Astrid Amundsen. "Speed and road accidents." An evaluation of the Power Model. TØI report 740 (2004): 2004.

World Health Organization. World health statistics 2015. World Health Organization, 2015.

Gargoum, Suliman A., and Karim El-Basyouny. “Exploring the Association Between Speed and Safety: A Path Analysis Approach.” Accident Analysis & Prevention 93 (August 2016): 32–40. doi:10.1016/j.aap.2016.04.029.

Gitelman, Victoria, Etti Doveh, and Shlomo Bekhor. “The Relationship Between Free-Flow Travel Speeds, Infrastructure Characteristics and Accidents, on Single-Carriageway Roads.” Transportation Research Procedia 25 (2017): 2026–2043. doi:10.1016/j.trpro.2017.05.398.

Tanishita, Masayoshi, and Bert van Wee. “Impact of Vehicle Speeds and Changes in Mean Speeds on Per Vehicle-Kilometer Traffic Accident Rates in Japan.” IATSS Research 41, no. 3 (October 2017): 107–112. doi:10.1016/j.iatssr.2016.09.003.

Sayed, Tarek, and Emanuele Sacchi. “Evaluating the Safety Impact of Increased Speed Limits on Rural Highways in British Columbia.” Accident Analysis & Prevention 95 (October 2016): 172–177. doi:10.1016/j.aap.2016.07.012.

Baruya, A. "Speed-accident relationships on European roads." In 9th International Conference on Road Safety in Europe. 1998.

American Association of State Highway, Transportation Officials. 2011. A Policy on Geometric Design of Highways and Streets, 2011. AASHTO.

Aljanahi, A.A.M, A.H Rhodes, and A.V Metcalfe. “Speed, Speed Limits and Road Traffic Accidents under Free Flow Conditions.” Accident Analysis & Prevention 31, no. 1–2 (January 1999): 161–168. doi:10.1016/s0001-4575(98)00058-x.

Garber, Nicholas, and Angela Ehrhart. “Effect of Speed, Flow, and Geometric Characteristics on Crash Frequency for Two-Lane Highways.” Transportation Research Record: Journal of the Transportation Research Board 1717 (January 2000): 76–83. doi:10.3141/1717-10.

Pei, Xin, S.C. Wong, and N.N. Sze. “The Roles of Exposure and Speed in Road Safety Analysis.” Accident Analysis & Prevention 48 (September 2012): 464–471. doi:10.1016/j.aap.2012.03.005.

Imprialou, Maria-Ioanna M., Mohammed Quddus, David E. Pitfield, and Dominique Lord. “Re-Visiting Crash–speed Relationships: A New Perspective in Crash Modelling.” Accident Analysis & Prevention 86 (January 2016): 173–185. doi:10.1016/j.aap.2015.10.001.

Ivan, John N, Chunyan Wang, and Nelson R Bernardo. “Explaining Two-Lane Highway Crash Rates Using Land Use and Hourly Exposure.” Accident Analysis & Prevention 32, no. 6 (November 2000): 787–795. doi:10.1016/s0001-4575(99)00132-3.

Berhanu, Girma. “Models Relating Traffic Safety with Road Environment and Traffic Flows on Arterial Roads in Addis Ababa.” Accident Analysis & Prevention 36, no. 5 (September 2004): 697–704. doi:10.1016/j.aap.2003.05.002.

Shankar, Venkataraman, Fred Mannering, and Woodrow Barfield. “Effect of Roadway Geometrics and Environmental Factors on Rural Freeway Accident Frequencies.” Accident Analysis & Prevention 27, no. 3 (June 1995): 371–389. doi:10.1016/0001-4575(94)00078-z.

Milton, John, and Fred Mannering. Transportation 25, no. 4 (1998): 395–413. doi:10.1023/a:1005095725001.

Elvik, Rune. “A Re-Parameterisation of the Power Model of the Relationship Between the Speed of Traffic and the Number of Accidents and Accident Victims.” Accident Analysis & Prevention 50 (January 2013): 854–860. doi:10.1016/j.aap.2012.07.012.

Karlaftis, Matthew G, and Ioannis Golias. “Effects of Road Geometry and Traffic Volumes on Rural Roadway Accident Rates.” Accident Analysis & Prevention 34, no. 3 (May 2002): 357–365. doi:10.1016/s0001-4575(01)00033-1.

Lee, Jinsun, and Fred Mannering. "Impact of roadside features on the frequency and severity of run-off-roadway accidents: an empirical analysis." Accident Analysis & Prevention 34, no. 2 (2002): 149-161.

Jalayer, Mohammad, and Huaguo Zhou. “Evaluating the Safety Risk of Roadside Features for Rural Two-Lane Roads Using Reliability Analysis.” Accident Analysis & Prevention 93 (August 2016): 101–112. doi:10.1016/j.aap.2016.04.021.

Castro, Marisol, Rajesh Paleti, and Chandra R. Bhat. “A Latent Variable Representation of Count Data Models to Accommodate Spatial and Temporal Dependence: Application to Predicting Crash Frequency at Intersections.” Transportation Research Part B: Methodological 46, no. 1 (January 2012): 253–272. doi:10.1016/j.trb.2011.09.007.

Ackaah, Williams, and Mohammed Salifu. “Crash Prediction Model for Two-Lane Rural Highways in the Ashanti Region of Ghana.” IATSS Research 35, no. 1 (July 2011): 34–40. doi:10.1016/j.iatssr.2011.02.001.

Rizaldi, Arief, Vinayak Dixit, Anurag Pande, and Rizky Adelwin Junirman. “Predicting Casualty-Accident Count by Highway Design Standards Compliance.” International Journal of Transportation Science and Technology 6, no. 3 (September 2017): 174–183. doi:10.1016/j.ijtst.2017.07.005.

National Research Council. Design speed, operating speed, and posted speed practices. No. 504. Transportation Research Board, 2003.

Hair, J. F. J., W. C. Black, B. J. Babin, and R. E. Anderson. "Multivariate Data Analysis Seventh Edition Prentice Hall." (2010).

De Arcangelis, Giuseppe. “Structural Equations with Latent Variables, Kenneth a. Bollen. John Wiley & Sons, Inc., New York, Chichester, Brisbane, Toronto, Singapore, 1989, Isbn 0-471-01171-1, £39.90 Hardbound, Pp. Xiv + 514.” Journal of Applied Econometrics 8, no. 1 (January 1993): 111–113. doi:10.1002/jae.3950080111.

De Oña, Juan, Rocío de Oña, Laura Eboli, and Gabriella Mazzulla. “Perceived Service Quality in Bus Transit Service: A Structural Equation Approach.” Transport Policy 29 (September 2013): 219–226. doi:10.1016/j.tranpol.2013.07.001.

Brown, Timothy A. Confirmatory factor analysis for applied research. Guilford Publications, 2014.

Xie, Kun, Kaan Ozbay, and Hong Yang. “Secondary Collisions and Injury Severity: A Joint Analysis Using Structural Equation Models.” Traffic Injury Prevention 19, no. 2 (October 23, 2017): 189–194. doi:10.1080/15389588.2017.1369530.

Hooper, Daire, Joseph Coughlan, and Michael Mullen. "Structural equation modelling: Guidelines for determining model fit." Articles (2008): 2.

Hu, Li‐tze, and Peter M. Bentler. “Cutoff Criteria for Fit Indexes in Covariance Structure Analysis: Conventional Criteria Versus New Alternatives.” Structural Equation Modeling: A Multidisciplinary Journal 6, no. 1 (January 1999): 1–55. doi:10.1080/10705519909540118.

Schumacker, Randall E., and Richard G. Lomax. A beginner's guide to structural equation modeling. Psychology Press, 2004.

Sadia, Reut, Shlomo Bekhor, and Abishai Polus. "Structural equations modelling of drivers' speed selection using environmental, driver, and risk factors." Accident Analysis & Prevention (2017). doi: 10.1016/j.aap.2017.08.034.

Arbuckle, James, and Werner Wothke. “Structural equation modeling using AMOS: An Introduction [EB].” (2004).

Zhu, Zhandong, and Jian Rong. “The Impact of the Accesses on the Operating Speed of Two-Lane Highways.” ICCTP 2010 (July 22, 2010). doi:10.1061/41127(382)101.

Full Text: PDF

DOI: 10.28991/cej-0309120


  • There are currently no refbacks.

Copyright (c) 2018 Behzad Bamdad Mehrabani, Babak Mirbaha

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.