Investigation of 4:1 V-Ditch Traversability and MASH Cable Barrier Test Matrices

The AASHTO Manual for Assessing Safety Hardware (MASH) provides a full-scale test matrix for evaluating cable median barriers on level terrain and sloped median ditches. The matrices define the critical placement of cable barriers and test criteria for 4:1 and 6:1 V-ditches to evaluate cable median barriers at various offsets or anywhere in a median V-ditch. Recent full-scale crash testing of cable median barriers mounted on the far side of a 4:1 V-ditch indicates that the 1100C small car vehicle may not be able to safely and consistently traverse a 4:1 V-ditch in MASH test no. 3-16. The 4:1 V-ditch configuration in the MASH 2016 test matrix uses a 46-ft wide V-ditch as measured from slope break point to slope break point. This V-ditch was selected based on preliminary full-scale crash tests of cable median barriers in V-ditches, vehicle dynamics simulations, and LS-DYNA simulations. The 4:1 slope was selected based on the maximum V-ditch slopes desired by state departments of transportations (DOTs). The ditch width was selected based on ditch traversal simulations to provide for a ditch capable of evaluating the maximum vehicle override potential on the front slope, the maximum vehicle underride potential during when a vehicle bottoms out on the backside of the V-ditch, and the maximum vehicle override potential when a vehicle rebounded from the bottom of the ditch and traversed up the backside of the ditch. Additionally, the AASHTO Roadside Design Guide (RDG) notes that 4:1 V-ditches are not a preferred configuration for median V-ditches, while flat bottom median ditch configurations are at the limit of the preferred configuration guidelines. Thus, the traversability of the V-ditch configuration recommended in MASH 2016 may be near the limit of vehicle stability. The objective of this research is to further investigate the traversability of 4:1 V-ditches and determine any needed updates to the MASH cable median barrier test matrix to ensure consistent performance of these ditches when evaluating cable median barriers.

• Record URL:
  http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=5699

Language

• English

Project

• Status: Proposed
• Funding: $750000
• Contract Numbers:

  Project 22-67

• Sponsor Organizations:

  National Cooperative Highway Research Program

  Transportation Research Board
  500 Fifth Street, NW
  Washington, DC  United States  20001

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590

  American Association of State Highway and Transportation Officials (AASHTO)

  444 North Capitol Street, NW
  Washington, DC  United States  20001
• Project Managers:

  Turner, Anne-Marie

• Start Date: 20240520
• Expected Completion Date: 0
• Actual Completion Date: 0

Subject/Index Terms

• TRT Terms: Crash tests; Ditches; Highway safety; Median barriers
• Subject Areas: Bridges and other structures; Design; Highways; Safety and Human Factors;

Filing Info

• Accession Number: 01919345
• Record Type: Research project
• Source Agency: Transportation Research Board
• Contract Numbers: Project 22-67
• Files: TRB, RIP
• Created Date: May 22 2024 11:49AM