The National Academies

NCHRP 20-07/Task 395 [Final]

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

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

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 (https://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 (https://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).
The objectives of this research project were 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.

The final report prepared under NCHRP Project 20-07/Task 395 is available online at:https://onlinepubs.trb.org/onlinepubs/nchrp/docs/NCHRP20-07(395)_FR.pdf
(NCHRP Staff: W. Dekelbab)

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