A previous study for the Iowa Highway Research Board (IHRB TR-592) provided an overview of the nation’s bridge and approach rail state of practice and of a statewide crash analysis of bridge rails and approach guardrails on low-volume road (LVR) bridges in Iowa. The study found that LVR bridge crashes were rare events, occurring more frequently on bridges with widths of less than 24 ft. Crash rates were found to be higher on bridges with a narrower width compared to the approach roadway width. Partly as a result of TR-592, changes were made to the guardrail exceptions in I.M. 3.213 to increase the average daily traffic (ADT) exception from 200 vehicles per day (vpd) to 400 vpd and add an exception for bridges with widths greater than the approach roadway width. However, no significant changes were made to the detailed bridge rail rating system component of I.M. 3.213, which is used to determine necessary bridge rail upgrades by assigning points to bridges based on crash history, ADT, width, length, and type of bridge rail. Thus, the current study was a follow-up to and builds on the results of TR-592.


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    Title :

    Upgrading Bridge Rails on Low-Volume Roads in Iowa. Tech Transfer Summary


    Contributors:
    Z. Hans (author) / B. A. Bektas (author) / B. Phares (author)

    Publication date :

    2016


    Size :

    3 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English




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