Purpose – The focus of this chapter is on state-of-the-art methodology for observational before–after evaluations. The purpose of such evaluations is to acquire information on the safety effects of site-specific treatments that could be used by road agencies for future interventions that may have an impact on safety. Methodology – Information, illustrated by a detailed example, is presented mainly on what is still regarded as the gold standard – the Empirical Bayes (EB) method. The methodology accounts for observed changes in crash frequencies that may be due to regression-to-the-mean, changes in traffic volume and time trends. Two related approaches – a comparison group method and the Full Bayes approach, which have been legitimately used for evaluations under special circumstances – are discussed in brief. Findings – The EB before–after methodology remains the gold standard but must be applied properly. Research implications – Some issues, for example, the selection of reference groups, still require further research. Practical implications – Key issues in the application of the before–after evaluation methods in general are also discussed.


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    Title :

    Chapter 18 Before–After Evaluations


    Contributors:

    Published in:

    Publication date :

    2018


    Remarks:

    Campusweiter Zugriff (Universität Hannover) - Vervielfältigungen (z.B. Kopien, Downloads) sind nur von einzelnen Kapiteln oder Seiten und nur zum eigenen wissenschaftlichen Gebrauch erlaubt. Keine Weitergabe an Dritte. Kein systematisches Downloaden durch Robots.




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English



    Classification :

    BKL:    55.84 Straßenverkehr / 55.20 Straßenfahrzeugtechnik
    DDC:    363.125 / 363.12