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                Development of Guidance for States Transitioning to New Safety Analysis Tools
**Description:**
        This report is intended to identify the data requirements and data availability for AASHTOWare Safety AnalystTM and the Highway Safety Manual (HSM) by working with both tools. It discusses the potential biases and issues associated with traditional safety analysis methods for selecting projects. The report presents Safety Performance Functions (SPFs) for various classifications of segments in Georgia and compares them against the national SPFs used in AASHTOWare Safety AnalystTM. It also investigates the influence of actual and estimated traffic data on the fit of the equations, questioning the accuracy and reliability of traffic estimations. The effect of using multiple CMFs is also studied by applying the HSM predictive methodology to two-way two-lane rural roads. Finally, the data requirements, predictive methodology, constraints, and results are compared between AASHTOWare Safety AnalystTM and the HSM.

The report provides benefits and trade-offs for agencies that are interested in using more rigorous approaches and new safety analysis tools. The main tradeoff for agencies is the requirement of having sufficient data (i.e., comprehensive and accurate) to use the tools. The research also compares results of analyses performed using the HSM versus AASHTOWare Safety AnalystTM predictive methods, showing that the default SPFs can lead to substantially different predictions. Note that the research was focused on network screening of roadway segments. The report does not provide results for intersections or ramps, and does not assess the other modules in AASHTOWare Safety AnalystTM.
    
          **Tool Type:**
        Informational Guide
    
    
    
          **Owner Source:**
        university
    
          **Sponsor/Owner:**
        Clemson University
    
        **Published:**
      2010
    
        **Availability:**
      The report is available for a fee at the following link: Guidance for States Transitioning to New Safety Analysis Tools.
    
          **Disclaimer:**
        This information is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained herein. This information does not constitute a standard, specification, or regulation. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturer's names appear in this information only because they are considered essential to the objective of this publication.
          Any opinions, findings, and conclusions or recommendations, and translations thereof, expressed in this publication are those of the author(s) and do not necessarily reflect the views of the Federal Highway Administration. U.S. DEPARTMENT OF TRANSPORTATION

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