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Mid-America Transportation Center

Simulation and Evaluation of a Cable-to-Post Attachment for High-Tension, Cable Barriers Placed in Medians along Freight Transportation Systems


Researchers

  • Principal Investigator: Robert Bielenberg (rbielenberg2@unl.edu 402-472-9064)
  • Co-Principal Investigator: John Reid (jreid1@unl.edu 402-472-3084)
  • Co-Principal Investigator: Ronald Faller (rfaller1@unl.edu 402-472-6864)
  • Co-Principal Investigator: Dean Sicking (dsicking@unl.edu (402)472-9332)
  • Project Status
    In Progress
    About this Project
    Brief Project Description & Background
    The research described herein will aid in the development and implementation of a new cable-to-post attachment for the four-cable, high-tension, cable median barrier being developed at MwRSF. Completion of the attachment design will allow MwRSF to complete the full-scale crash tests necessary for the system to be safely implemented on the nation's highways. In addition, this research will help evaluate the performance of the end terminal design required for the ends of the barrier. This non-proprietary cable barrier design is anticipated to be implemented by a large number of State Departments of Transportation and represents a significant step forward in the design of cable median barriers.
    Research Objective
    The objective of this research is to develop a new cable-to post attachment for a high-tension, four cable, median barrier system. During the ongoing development of the high-tension, four cable, median barrier system, a serious flaw was identified in the design of the cable-to-post attachment which resulted in the failure of the system during full-scale crash testing. Refinements to this cable attachment bracket, or the implementation of a new bracket, should prevent this unfavorable outcome. Development of a new cable-to-post attachment is currently in progress. This proposal seeks to supplement the development of a new cable-to-post attachment through computer simulation and component testing.
    Potential Benefits
    This research would serve to provide a vast improvement in the performance cable median barriers both in terms of safety performance and constructability. The completed cable median barrier design would have the ability to be placed at any location within a 4H:1V V-ditch median. This makes the design easy to implement and gives designers more flexibility, thus ensuring that economical median barriers can be installed in areas where they are needed. This project has the potential to improve the safety of our nation's freight and public transportation systems by reducing the number of cross-median accidents as well as the number of severe injuries and fatalities. Finally, this research study would also allow for new, upcoming engineers (graduate research assistants) to gain knowledge and experience in the field of transportation safety and learn to develop and apply innovative solutions to those problems found within our U.S. transportation system.
    Abstract
    Cable barriers are a common safety device used on our nation's highway system. Recently, there has been a surge in the installation of high-tension, cable median barrier designs to limit median cross-over accidents on divided highways. A critical component of these cable median barriers is the cable-to-post attachment. For these types of barriers to be safe and effective, the cable-to-post attachment must successfully develop the load capacity of the support posts when the cable is loaded laterally. In addition, the cable-to-post attachments must have the ability to release the cables from the posts when loaded in the vertical direction so that the cables are not pulled downward as the posts rotate, thus preventing the impacting vehicle from overriding the barrier system. The Midwest Roadside Safety Facility (MwRSF) is currently developing a non-proprietary, four-cable, high-tension, cable median barrier that can be placed at any location in 4H:1V median ditches. A significant portion of that effort has involved the development of various cable-to-post attachments. The initial design of the cable-to-post attachment was a keyway bracket design that mounted on the post with shoulder bolts. Full-scale crash testing of the keyway bracket attachment demonstrated that the exposed bolt heads were sufficient to prevent upward cable movement at some post locations, thus preventing the translation of certain tensioned cables up and over the vehicle. The inability of the cable to translate up and over the vehicle resulted in excessive roof deformation and inward crush into the vehicle's occupant compartment, thus resulting in the failure of the crash test. Refinements to this cable attachment bracket, or the implementation of a new bracket, should prevent this unfavorable outcome. Development of a new cable-to-post attachment is currently in progress. This proposal seeks to supplement the development of a new cable-to-post attachment through computer simulation and component testing.
    Project Amount
    $ 272,081
    Modal Orientation
  • Freight
  • Highways
  • Structures
  • Technology Transfer Activities
    The research study recommended herein would be directed toward improving the safety of the motoring public traveling within major freight transportation infrastructure systems, including the interstate and highway systems. Specifically, this research project would support the fourth focus area, �Increasing the overall safety of the surface transportation system users,� by developing an improved cable-to-post attachment and completing the design of the four-cable, high-tension, median barrier system.