Development of a MASH Barrier to Shield Pedestrians, Bicyclists, and Other Vulnerable Users from Motor Vehicles

As the number of pedestrians, bicyclists and users of other active transportation modes continues to grow in the United States, state departments of transportation (DOTs) are seeking to improve how these users are accommodated on or adjacent to our nation’s roadways. Despite these efforts, some roadways have limited lateral offsets between the motor vehicle travel lanes and the sidewalks or multi-use paths that can reduce actual and/or perceived safety for these vulnerable users. When available right-of-way and/or project funding constrain transportation agencies’ ability to increase this offset distance, an alternative can be to install a positive protection device—a barrier that separates lanes for motorized vehicles and facilities for vulnerable users. Traditionally, barriers are designed for a specific need such as shielding motorists from a steep slope or a fixed object in the clear zone. The selection of a barrier is driven by roadway design speed, traffic volume, and clear zones, along with considerations such as the accommodation of access points, climate conditions, and aesthetics. However, the use of barriers to separate pedestrians and bicycles from motor vehicles requires the consideration of additional factors to address safety for all users. For example, a typical guardrail is designed to redirect motor vehicles, but may not be tall enough to protect pedestrians by preventing inadvertent encroachment into the roadway. Guardrail designs may have bolts or other features that can snag a vulnerable user. Geometric conditions, such as a vertical separation between the motor vehicle travel lanes and the pedestrian or bicycle facility, may change the performance of the barrier. Additionally, when struck by a motor vehicle, a barrier may deflect into the path of a vulnerable user. While a concrete barrier can satisfy many requirements, alternative, lower-cost designs are needed, especially designs with open railings that allow visibility. Previously published guidance includes some information on barrier designs to separate vulnerable users from motor vehicle traffic; however, design specifics are incomplete and may not address the most common design contexts where a new barrier or modification to an existing barrier is needed for positive protection. Research is needed to develop a barrier with design and performance characteristics that address safety for vulnerable users and for motorists while satisfying the proposed Public Right-of-Way Accessibility Guidelines (PROWAG) and the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) criteria. To ensure a design is appropriate for commonly encountered design contexts and challenges, it must be informed by a review of current practice that identifies gaps between current practice and crashworthy barrier solutions. The objective of this research is to develop a minimum of one nonproprietary barrier design for use in separating vulnerable users from motor vehicle travel lanes that is tested to appropriate MASH criteria, complies with PROWAG, and is cost-effective. An acceptable design could be for a completely new barrier or one that modifies an existing barrier. The barrier design shall provide positive protection by redirecting motor vehicles and include design elements that also increase safety of vulnerable users. The barrier design should be appropriate for commonly encountered design contexts. Task descriptions are intended to provide a framework for conducting the research. The National Cooperative Highway Research Program (NCHRP) is seeking the insights of proposers on how best to achieve the research objective. Proposers are expected to describe research plans that can realistically be accomplished within the constraints of available funds and contract time. Proposals must present the proposers' current thinking in sufficient detail to demonstrate their understanding of the issues and the soundness of their approach to meeting the research objective. Task 1. Develop an updated review of relevant research, both in the United States and internationally. The review should collect information on barrier designs, including promising designs that may not yet have been tested. Task 2. Solicit information from transportation agencies, design consultants, vulnerable user groups, and, as appropriate, transportation agencies outside the United States, on typical project types and design contexts where a tested barrier to separate motor vehicles from vulnerable users is needed. Task 3. Develop a technical memorandum summarizing the results of Tasks 1 and 2 and identifying and prioritizing design needs. The memorandum will describe one or more preliminary proposed barrier design and performance parameters for testing (for example, barrier height, deflection, and similar).  Task 4. Based on the results of Tasks 1 through 3, develop the proposed barrier design and model its crashworthiness. Provide a technical memorandum with barrier design details, results of simulation models, and recommended crash tests. Task 5. Construct full-scale crash tests to the appropriate MASH test level. Provide a technical memorandum and additional materials, such as videos, to document the crash test results. Task 6. Develop final deliverables. (1) A final report to include: (a) Documentation of the research effort; (b) Stand-alone drawings and specifications of the barrier design; (c) Results of the crash tests and simulation models; (d) Documentation of  the barrier design, simulation model results, and crash test results in a format that can be used by a state DOT to demonstrate MASH compliance; (e) Suggested terminal options to be fully designed and tested in future studies; and (f) Recommendations for additional needed research. (2) A PowerPoint presentation with speaker notes that summarizes the project (3) At least one presentation of the research results to an audience composed of individuals who will be key to the implementation of the results of the research. Potential audiences include the AASHTO Technical Committee for Roadside Safety and the AASHTO Committee on Design.

Language

  • English

Project

  • Status: Proposed
  • Funding: $500000
  • Contract Numbers:

    Project 22-37

  • Sponsor Organizations:

    National Cooperative Highway Research Program

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

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Hartell, Ann

  • Start Date: 20190318
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01672557
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 22-37
  • Files: TRB, RiP
  • Created Date: Jun 18 2018 3:03PM