Skip to main content
Log in

Evaluating Time Trend Correction Approaches Associated with Empirical Bayes Before-after Study for Road Safety

  • Transportation Engineering
  • Published:
KSCE Journal of Civil Engineering Aims and scope Submit manuscript

Abstract

The Empirical Bayes (EB) before-after study is used extensively for reliable safety evaluation. The EB method has the advantage of addressing confounding factors, including the regression-to-the-mean phenomenon and change of traffic volume. The EB method can also address the time trend effect by two approaches, i.e., the Yearly Multiplier (YM) and the Simple Crash Ratio of a Reference group (SCRR). However, the use of the YM without adjusting the over-dispersion parameter may induce a biased estimation of the Bayesian inference. This study aims to provide the systematic evaluation of the two approaches for correcting the time trend. To achieve this, a numerical example and its sensitivity analysis are presented. The bias due to the use of the YM is also measured based on the empirical data from Korean freeways. The findings of this study show the EB method with SCRR would be a useful approach as a time trend correction approach, especially when the reference group has experienced a considerable time trend.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Similar content being viewed by others

References

  • Abdel-Aty, M., Devarasetty, P. C., and Pande, A. (2009). “Safety evaluation of multilane arterials in Florida.” Accident Analysis and Prevention, Vol. 41, No. 4, pp. 777–788, DOI: 10.1016/j.aap.2009.03.015.

    Article  Google Scholar 

  • American Association of State Highway and Transportation Officials (AASHTO). (2010). Highway Safety Manual, AASHTO, Washington D.C., USA.

  • Cameron, A. C. and Trivedi, P. K. (1998). Regression analysis of count data. Cambridge University Press, Cambridge, UK.

    Book  MATH  Google Scholar 

  • Carlin, B. P. and Louis, T. A. (1997). Bayes and empirical Bayes methods for data analysis, Chapman and Hall, London, UK.

    MATH  Google Scholar 

  • De Pauw, E., Daniels, S., Brijs, T., Hermans, E., and Wets, G. (2014). “To brake or to accelerate? Safety effects of combined speed and red light cameras.” Journal of Safety Research, Vol. 50, pp. 59–65, DOI: 10.1016/j.jsr.2014.03.011.

    Article  Google Scholar 

  • El-Basyouny, K. and Sayed, T. (2011). “A full bayes multivariate intervention model with random parameters among matched pairs for before–after safety evaluation.” Accident Analysis and Prevention, Vol. 43, No.1, pp. 87–94, DOI: 10.1016/j.aap.2010.07.015.

    Article  Google Scholar 

  • Elvik, R. (1997). “Effects on accidents of automatic speed enforcement in Norway.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 1595, pp. 14–19, DOI: 10.3141/1595-03.

    Article  Google Scholar 

  • Elvik, R. (2002). “The importance of confounding in observational before-and-after studies of road safety measures.” Accident Analysis and Prevention, Vol. 34, No. 5, pp. 631–635, DOI: 10.1016/S0001-4575(01)00062-8.

    Article  Google Scholar 

  • Fitzpatrick, K. and Park, E. (2009). “Safety effectiveness of HAWK pedestrian treatment.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 2140, pp. 214–223, DOI: 10.3141/2140-24.

    Article  Google Scholar 

  • Gross, F., Persaud, B., and Lyon, C. (2010). A guide to developing quality crash modification factors, FHWA-SA-10-032, FHWA, Washington D.C., USA.

    Google Scholar 

  • Hauer, E. (1997). Observational Before-After Studies in Road Safety: Estimating the Effect of Highway and Traffic Engineering Measures on Road Safety, Pergamon press, Oxford, UK.

    Google Scholar 

  • Hauer, E., Harwood, D., Council, F., and Griffith, M. (2002). “Estimating safety by the empirical Bayes method: A tutorial.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 1784, pp. 126–131, DOI: 10.3141/1784-16.

    Article  Google Scholar 

  • Kim, D., Kim, D. K., and Lee, C. (2013). “Safety performance functions reflecting categorical impact of exposure variables for freeways.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 2398, pp. 67–74, DOI: 10.3141/2398-08.

    Article  Google Scholar 

  • Lee, J., Chung, K., and Kang, S. (2016). “Evaluating and addressing the effects of regression to the mean phenomenon in estimating collision frequencies on urban high collision concentration locations.” Accident Analysis and Prevention, Vol. 97, pp. 49–56, DOI: 10.1016/j.aap.2016.08.019.

    Article  Google Scholar 

  • Lyon, C., Haq, A., Persaud, B., and Kodama, S. (2005). “Safety performance functions for signalized intersections in large urban areas: Development and application to evaluation of left-turn priority treatment.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 1908, pp. 165–171, DOI: 10.3141/1908-20.

    Article  Google Scholar 

  • Naznin, F., Currie, G., Sarvi, M., and Logan, D. (2016). “An empirical Bayes safety evaluation of tram/streetcar signal and lane priority measures in Melbourne.” Traffic Injury Prevention, Vol. 17, No. 1, pp. 91–97, DOI: 10.1080/15389588.2015.1035369.

    Article  Google Scholar 

  • Park, J., Abdel-Aty, M., and Lee, C. (2014). “Exploration and comparison of crash modification factors for multiple treatments on rural multilane roadways.” Accident Analysis and Prevention, Vol. 70, pp. 167–177, DOI: 10.1016/j.aap.2014.03.016.

    Article  Google Scholar 

  • Park, S., Jang, K., Park, S. H., Kim, D. K., and Chon, K. S. (2012). “Analysis of injury severity in traffic crashes: A case study of Korean expressways.” KSCE Journal of Civil Engineering, Vol. 16, No. 7, pp. 1280–1288, DOI: 10.1007/s12205-012-1527-3.

    Article  Google Scholar 

  • Park, E. S., Park, J., and Lomax, T. J. (2010). “A fully Bayesian multivariate approach to before–after safety evaluation.” Accident Analysis and Prevention, Vol. 42, No. 4, pp. 1118–1127, DOI: 10.1016/j.aap.2009.12.026.

    Article  Google Scholar 

  • Patel, R., Council, F., and Griffith, M. (2007). “Estimating safety benefits of shoulder rumble strips on Two-Lane rural highways in minnesota: Empirical bayes observational before-and-after study.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 2019, pp. 205–211, DOI: 10.3141/2019-24.

    Article  Google Scholar 

  • Persaud, B., Hauer, E., Retting, R., Vallurupalli, R., and Mucsi, K. (1997). “Crash reductions related to traffic signal removal in Philadelphia.” Accident Analysis and Prevention, Vol. 29, No. 6, pp. 803–810, DOI: 10.1016/S0001-4575(97)00049-3.

    Article  Google Scholar 

  • Persaud, B., Retting, R., Garder, P., and Lord, D. (2001). “Safety effect of roundabout conversions in the united states: Empirical bayes observational before-after study.” Transportation Research Record: Journal of the Transportation Research Board, Vol. 1751, pp. 1–8, DOI: 10.3141/1751-01.

    Article  Google Scholar 

  • Persaud, B. N., Retting, R. A., and Lyon, C. A. (2004). “Crash reduction following installation of centerline rumble strips on rural two-lane roads.” Accident Analysis and Prevention, Vol. 36, No. 6, pp. 1073–1079, DOI: 10.1016/j.aap.2004.03.002.

    Article  Google Scholar 

  • Shin, K., Washington, S., and Van Schalkwyk, I. (2009). “Evaluation of the Scottsdale Loop 101 Automated speed enforcement demonstration program.” Accident Analysis and Prevention, Vol. 41, No. 3, pp. 393–403, DOI: 10.1016/j.aap.2008.12.011.

    Article  Google Scholar 

  • Washington, S. P., Karlaftis, M. G., and Mannering, F. L. (2003). Statistical and econometric methods for transportation data analysis, Chapman Hall/CRC, Boca Raton, FL, USA.

    Book  MATH  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Dong-Kyu Kim.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Choi, YY., Kho, SY., Jang, K. et al. Evaluating Time Trend Correction Approaches Associated with Empirical Bayes Before-after Study for Road Safety. KSCE J Civ Eng 22, 4593–4601 (2018). https://doi.org/10.1007/s12205-017-0162-4

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s12205-017-0162-4

Keywords

Navigation