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The National Academies

NCHRP 20-07/Task 395 [Active]

MASH Equivalency of NCHRP 350-Approved Bridge Railings
[ NCHRP 20-07 (Research for AASHTO Standing Committee on Highways) ]

  Project Data
Funds: $150,000
Staff Responsibility: Dr. Waseem Dekelbab
Research Agency: Texas A&M Transportation Institute
Principal Investigator: Dr. Roger P. Bligh
Effective Date: 6/7/2016
Completion Date: 11/30/2017

BACKGROUND
 
The American Association of State Highway and Transportation Officials (AASHTO) will soon be publishing an updated edition of the Manual for Assessing Safety Hardware (MASH), the document defining criteria for crash testing hardware. Along with this, FHWA and AASHTO are developing a revised joint implementation agreement which will establish dates for discontinuing the use of safety hardware that has met earlier crash testing criteria for new installations and full replacements on the National Highway System.
 
There are many types of non-proprietary bridge rails in use throughout the states and research is needed to determine which rails need to be retested to MASH criteria and which, if any, can be "grandfathered" based on evaluation under previous criteria. In 1997, FHWA provided a list of 74 bridge rails and their equivalent NCHRP 350 test level, based on the earlier NCHRP Report 230 test levels and AASHTO Bridge Specifications performance levels (http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/barriers/bridgerailings/docs/appendixb5.pdf). In 2000, FHWA provided guidance that allows for demonstrating that variations of a bridge rail design would not have to be crash tested if the basic geometry of a bridge rail has not been changed and the structural design of the rail is comparable to the rail that has been tested (http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/barriers/bridgerailings/docs/bridgerail_analysis_may16.pdf). With the pending approval and publication of an update to MASH and proposed joint AASHTO/FHWA implementation agreement, there is a need to review these resources, determine whether the concept is still appropriate, and also modify as needed to account for MASH (in other words, determine equivalent MASH test levels for bridge railings and which rail needs to be retested).
 
OBJECTIVE
The objectives of this research project are to: (1) prioritize bridge railings including concrete barrier,  (2) determine MASH equivalent test levels, and (3) determine whether individual types of bridge railing could be submitted to FHWA for determination of Federal-aid reimbursement eligibility or whether retesting is needed.
 
TASKS
 
Task 1. Determination of how commonly various bridge railings will be used in the United States (i.e., level of interest for determining whether a rail meets MASH), through a poll, survey, review of standard drawings, or other means, to establish a priority for evaluation.
 
Task 2. Assessment of methodology previously accepted by FHWA as appropriate for analyzing variations of fully crash tested bridge rail designs, for appropriateness for use with MASH crash test criteria.
 
Note: Submit a draft letter report for Tasks 1 and 2 no later than 4 months after contract award. NCHRP approval will be required before proceeding with the remaining tasks.
 
Task 3. Analysis of bridge rails to determine whether crash testing is needed or if a MASH test level equivalent can be established using data already known.  
 
Task 4. Coordination with pooled fund and other research initiatives to share information, avoid duplication of efforts, and work toward compiling information on all devices that meet MASH in one location.
 
Task 5. Compilation of information and letters for devices not requiring re-testing for FHWA to determine eligibility of the devices for the Federal-aid reimbursement.
 
Task 6. Presentation of the research findings to the AASHTO Subcommittee on Bridges and Structures, Technical Committees: T-7 Guardrail and Bridge Rail and AASHTO Technical Committee on Roadside Safety.
 
Task 7. Submission of the final report describing the entire research. Following receipt of the draft final report, the remaining 2 months shall be for NCHRP review and comment and for research agency preparation of the revised final report.

STATUS: Research in progress

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