Highlights Assessing the transferability of a crash modification factor is an example of assessing external validity. Assessing external validity almost certainly requires understanding how a modification works. A case study is presented developing and testing an explanation for a crash modification effect. Guidance to others wanting to develop explanations is provided.

    Abstract Although the Highway Safety Manual (HSM) now provides empirical tools for predicting the safety consequences of highway engineering decisions, these tools represent the driver and vehicle conditions prevailing in the United States during the last few decades. As automated vehicles improve in capability and increase in market share these conditions will change, possibly reducing the accuracy of HSM predictions. Assessing the transferability of a crash modification factor to new situations almost certainly requires an explanation of how the modification achieves its effect, but at present there is little guidance on how such explanations might be posed and tested. This paper describes the use of micro-simulation to develop an explanation of how pedestrian hybrid beacons (PHB) modify pedestrian crash likelihood. Since the literature indicated that PHBs can affect both pedestrian and driver behavior it was necessary to include both possibilities in the model. To simulate injury severity distributions similar to those recorded in a crash database it was necessary to propose that almost all simulated drivers attempt to brake in pedestrian/vehicle encounters. Then changing the simulated fraction of careful pedestrians from between 0% and 30% to between 80% and 90% gave simulated crash modification factors similar to estimates reported in the literature. The resulting working hypothesis then is that PHBs achieve their crash reduction effect in large part by modifying pedestrian behavior. This is not so much a direct observation as it is an inference to the best explanation. That is, the support for the hypothesis comes from its ability to explain the data at hand. This hypothesis should be tested further, and additional tests are proposed.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Explaining crash modification factors: Why it’s needed and how it might be done


    Beteiligte:
    Davis, Gary A. (Autor:in)

    Erschienen in:

    Erscheinungsdatum :

    2019-06-29


    Format / Umfang :

    9 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch




    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


    Why crash protection is needed

    Stieglitz, W.I. | Engineering Index Backfile | 1950


    Intersection Safety Improvement Using Crash Modification Factors

    Abdulhafedh, Azad Salim / Selman, Mudhafer H. / Sadeeq, Heleen Faris | Springer Verlag | 2022