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Mid-America Transportation Center

Highway Safety Manual Applied in Missouri-Freeway Software

Final Report
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Researchers

  • Principal Investigator: Carlos Sun (csun@missouri.edu 573-884-6330)
  • Project Status
    Complete
    About this Project
    Brief Project Description & Background
    AASHTO is preparing to release a revision to the Highway Safety Manual that includes models for freeway segments, speed-change lanes, and interchanges. Select models that are relevant to MATC states will be calibrated using local sites and local crash data. The calibration of such models will ensure that they reflect local driver populations, conditions, and environments. The HSM has a related software package, the Safety Analyst (SA). This software will be investigated for the generation of the annual needs list (high-severity facilities). There have been some facilities that are unique to the MATC states that do not have HSM models. Two examples are the diverging diamond (or double-crossover) and the J-turn. This project will also develop safety performance functions for these innovative geometric designs that are designed to reduce severe crashes.
    Research Objective
    The new Highway Safety Manual (HSM) provides methods and tools to assist in the quantitative evaluation of safety. The HSM will be revised to include the modeling of freeways, including segments, speed-change lanes, and interchanges. These new models will need to be calibrated in order to reflect local driver populations, conditions, and environments. Some relevant local conditions include driver population, geometric design, signage, traffic control devices, signal timing practices, climate, and animal population. A second aspect of this project is an investigation of the Safety Analyst (SA) software for generating annual needs lists (i.e., high-severity facilities lists). This project will develop models for facilities that are unique to the MATC states.
    Potential Benefits
    This project directly supports all four key focus areas of MATC and the US DOT: enhancing safety, improving the state of good repair, improving economic competitiveness, and improving the environmental sustainability of the U.S. surface transportation system. The most obvious area that this project will support is enhancing safety. The HSM and SA can be used to identify possible locations for reducing high crash frequencies or severities. It can be used to identify factors contributing to crashes, and appropriate countermeasures to mitigate safety issues. The safety benefits can be achieved throughout the planning, design, and operations stages. Another area is assisting with the repair of infrastructure. Because of the elevated risks associated with work zones, it is important to include safety in implementing maintenance and rehabilitation work. This project also supports the goal of economic competitiveness because the HSM facilitates the estimation of crash reduction benefits, design alternatives, and project improvements. Lastly, the HSM can be a useful tool during the NEPA (National Environmental and Policy Act) process for performing environmental and traffic impact analysis. In examining design alternatives during the NEPA process, safety is a major concern.
    Abstract
    AASHTO is preparing to release a revision to the Highway Safety Manual that includes models for freeway segments, speed-change lanes, and interchanges. Select models that are relevant to MATC states will be calibrated using local sites and local crash data. The calibration of such models will ensure that they reflect local driver populations, conditions, and environments. The HSM has a related software package, the Safety Analyst (SA). This software will be investigated for the generation of the annual needs list (high-severity facilities). There have been some facilities that are unique to the MATC states that do not have HSM models. Two examples are the diverging diamond (or double-crossover) and the J-turn. This project will also develop safety performance functions for these innovative geometric designs that are designed to reduce severe crashes.  
    Project Amount
    $ $94,797