Crash modification factors (CMFs) can be used to capture the safety effects of countermeasures and play a significant role in traffic safety management. As an alternative to the before-and-after study, the regression model method has been widely used for estimating CMFs. Although before-and-after studies are considered to be superior, the use of regression models for estimating CMFs has never been fully investigated. Consequently, the conditions in which regression models could be used for such a purpose were examined. CMFs for three variables—lane width, curve density, and pavement friction—were assumed and used for generating random crash counts. Then CMFs were derived from regression models by using the simulated crash data for three different scenarios. The results were then compared with the assumed true values. The study results showed that (a) when all factors affecting traffic safety are identical in all segments except those of interest, CMFs derived from regression models should be unbiased; (b) if some factors having minor safety effects are omitted from the models, the accuracy of estimated CMFs can still be acceptable; and (c) if some factors already known to have significant effects on crash risk are omitted, CMFs derived from the regression models are generally unreliable. Thus, depending on missing variables not included in the model, the transportation safety analyst can decide whether CMFs developed from regression models should be used for highway safety applications.


    Access

    Download

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Validation of Crash Modification Factors Derived from Cross-Sectional Studies with Regression Models


    Additional title:

    Transportation Research Record: Journal of the Transportation Research Board


    Contributors:
    Wu, Lingtao (author) / Lord, Dominique (author) / Zou, Yajie (author)


    Publication date :

    2015-01-01




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



    Developing crash modification factors for roundabouts using a cross-sectional method

    Mohammad Nour Al-Marafi / Kathirgamalingam Somasundaraswaran / Ron Ayers | DOAJ | 2020

    Free access

    Crash Modification Factors

    Hauer, Ezra / Bonneson, James A. / Council, Forrest et al. | Transportation Research Record | 2012


    Crash reconstruction and crash modification factors

    Davis, Gary A. | Online Contents | 2014



    Developing Crash Modification Factors for Horizontal Curves on Rural Two-Lane Undivided Highways Using a Cross-Sectional Study

    Wu, Lingtao / Lord, Dominique / Geedipally, Srinivas Reddy | Transportation Research Record | 2017