Modeling Speed Mean and Variance for Different Enforcement Conditions on Multilane Highways
Publication: Journal of Transportation Engineering, Part A: Systems
Volume 149, Issue 8
Abstract
Two major characteristics that can impact the frequency and severity of traffic crashes are average speed and speed variance. This paper investigated these characteristics on 49 multilane highway segments in Jordan and developed prediction models for three different conditions: free (no enforcement), camera, and police enforcement. Speed data were collected during off-peak periods with fair weather conditions. Multiple linear regressions and nonlinear regressions were used to develop speed variance and average speed models. For the free condition, speed variance mainly depends on the difference between design speed and speed limit (DS-SL), with the speed variance decreasing as the difference reduces, while the average speed was positively correlated with the design speed. Camera enforcement causes speed variance and average speed to be positively correlated and linearly dependent with the speed limit. A quadratic relationship was found between speed variance during police enforcement and DS-SL, while the average speed during police enforcement depended on the speed limit and design speed. These modeling results, along with analysis of the collected data, can help operating agencies and roadway designers determine how various enforcement strategies affect average speed and speed variance and better set speed limits on existing and future roadways to improve safety.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.
Acknowledgments
Co-author Prof. Bashar H. Al-Omari died prior to the submission of this paper. This is one of his last works.
References
Alomari, A. H., B. H. Al-Omari, and M. E. Al-Adwan. 2021a. “Analysis of speed variance on multilane highways in Jordan.” In Proc., 1st Int. Congress on Engineering Technologies, 206–216. Boca Raton, FL: CRC Press.
Alomari, A. H., B. H. Al-Omari, M. E. Al-Adwan, and A. Sandt. 2021b. “Investigating and modeling speed variability on multilane highways.” Adv. Transp. Stud. 54 (Jul): 5–16.
Cheng, W., J. H. Wang, G. Bryden, X. Ye, and X. Jia. 2013. “An examination of the endogeneity of speed limits and accident counts in crash models.” J. Transp. Saf. Secur. 5 (4): 314–326. https://doi.org/10.1080/19439962.2013.778928.
De Pauw, E., S. Daniels, T. Brijs, E. Hermans, and G. Wets. 2014. “An evaluation of the traffic safety effect of fixed speed cameras.” Saf. Sci. 62 (Feb): 168–174. https://doi.org/10.1016/j.ssci.2013.07.028.
Elvik, R. 2010. “A restatement of the case for speed limits.” Transp. Policy 17 (3): 196–204. https://doi.org/10.1016/j.tranpol.2009.12.006.
Feng, C. 2001. “Synthesis of studies on speed and safety.” Transp. Res. Rec. 1779 (1): 86–92. https://doi.org/10.3141/1779-12.
Fitzpatrick, K., P. Carlson, M. A. Brewer, M. D. Wooldridge, and S. P. Miaou. 2003. Design speed, operating speed, and posted speed practices. Washington, DC: Transportation Research Board of the National Academies.
Forbes, G., T. Gardner, H. McGee, and R. Srinivasan. 2012. Methods and practices for setting speed limits: An informational report. Washington, DC: US DOT.
Garber, N. J., and R. Gadirau. 1989. “Factors affecting speed variance and its influence on accidents.” Transp. Res. Rec. 1989 (1213): 64–71.
Gaweesh, S. M., and M. M. Ahmed. 2020. “Evaluating the safety effectiveness of a weather-based variable speed limit for a rural mountainous freeway in Wyoming.” J. Transp. Saf. Secur. 12 (10): 1205–1230. https://doi.org/10.1080/19439962.2019.1583707.
Gayah, V. V., E. T. Donnell, Z. Yu, and L. Li. 2018. “Safety and operational impacts of setting speed limits below engineering recommendations.” Accid. Anal. Prev. 121 (Dec): 43–52. https://doi.org/10.1016/j.aap.2018.08.029.
Graves, P. E., D. R. Lee, and R. L. Sexton. 1993. “Speed variance, enforcement, and the optimal speed limit.” Econ. Lett. 42 (2–3): 237–243. https://doi.org/10.1016/0165-1765(93)90068-N.
Ha, T. J., J. G. Kang, and J. J. Park. 2003. “The effects of automated speed enforcement systems on traffic-flow characteristics and accidents in Korea.” ITE J. 73 (2): 28–31.
Hu, W. 2017. “Raising the speed limit from 75 to 80 mph on Utah rural interstates: Effects on vehicle speeds and speed variance.” J. Saf. Res. 61 (Jun): 83–92. https://doi.org/10.1016/j.jsr.2017.02.006.
IBM. 2021. “IBM SPSS software, version 25.” Accessed September 5, 2021. https://www.ibm.com/products/spss-statistics.
Islam, M. T., K. El-Basyouny, and S. E. Ibrahim. 2014. “The impact of lowered residential speed limits on vehicle speed behavior.” Saf. Sci. 62 (Feb): 483–494. https://doi.org/10.1016/j.ssci.2013.10.006.
Malyshkina, N. V., and F. L. Mannering. 2008. “Effect of increases in speed limit on severities of injuries in accident.” Transp. Res. Rec. 2083 (1): 122–127. https://doi.org/10.3141/2083-14.
Mathew, T. V. 2014. “Transportation systems engineering.” Chap. 23 in Multilane highway, 1–19. Mumbai, India: Indian Institute of Technology.
Pisarski, A. E. 1986. “Deep-six 55.” Reason Found. 17 (6): 32–35.
Quddus, M. 2013. “Exploring the relationship between average speed, speed variation, and accident rates using spatial statistical models and GIS.” J. Transp. Saf. Secur. 5 (1): 27–45. https://doi.org/10.1080/19439962.2012.705232.
Rock, S. M. 1995. “Impact of the 65-mph speed limit on accidents, deaths, and injuries in Illinois.” Accid. Anal. Prev. 27 (2): 207–214. https://doi.org/10.1016/0001-4575(94)00058-T.
Ryeng, E. O. 2012. “The effect of sanctions and police enforcement on drivers’ choice of speed.” Accid. Anal. Prev. 45 (Mar): 446–454. https://doi.org/10.1016/j.aap.2011.08.010.
Soole, D. W., B. C. Watson, and J. J. Fleiter. 2013. “Effects of average speed enforcement on speed compliance and crashes: A review of the literature.” Accid. Anal. Prev. 54 (May): 46–56. https://doi.org/10.1016/j.aap.2013.01.018.
TxDOT (Texas DOT). 2021. “Setting speed limits.” Accessed September 5, 2021. https://www.txdot.gov/driver/laws/speed-limits/setting.html.
Wang, X., T. Fan, W. Li, R. Yu, D. Bullock, B. Wu, and P. Tremont. 2016. “Speed variation during peak and off-peak hours on urban arterials in Shanghai.” Transp. Res. Part C: Emerging Technol. 67 (Jun): 84–94. https://doi.org/10.1016/j.trc.2016.02.005.
Wang, X., Q. Zhou, M. Quddus, and T. Fan. 2018. “Speed, speed variation and crash relationships for urban arterials.” Accid. Anal. Prev. 113 (Apr): 236–243. https://doi.org/10.1016/j.aap.2018.01.032.
Information & Authors
Information
Published In
Journal of Transportation Engineering, Part A: Systems
Volume 149 • Issue 8 • August 2023
Copyright
© 2023 American Society of Civil Engineers.
History
Received: Oct 19, 2021
Accepted: Mar 24, 2023
Published online: May 25, 2023
Published in print: Aug 1, 2023
Discussion open until: Oct 25, 2023
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.