The National Academies

NCHRP 22-35 [Final]

Evaluation of Bridge Rail Systems to Confirm AASHTO MASH Compliance

  Project Data
Funds: $500,000
Research Agency: Texas A&M Transportation Institute
Principal Investigator: Mr. William Williams
Effective Date: 6/1/2018
Completion Date: 6/1/2022
Comments: Published as NCHRP Research Report 1024

The American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) is the latest in a series of documents that provides guidance on testing and evaluation of roadside safety features. This document, initially published in 2009 and updated in 2016, represents a comprehensive update to crash test and evaluation procedures to reflect changes in the vehicle fleet, operating conditions, and roadside safety knowledge and technology. It superseded NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features.
The AASHTO Technical Committee on Roadside Safety (TCRS) and the Federal Highway Administration (FHWA) have adopted a new MASH implementation plan that has compliance dates for installing MASH hardware that differ by hardware category. After December 31, 2019, all new installations of bridge rails on the NHS must have been successfully evaluated according to the 2016 edition of MASH. Similar to NCHRP Report 350, MASH defines six test levels for longitudinal barriers. With respect to AASHTO LRFD Bridge Design Specifications, each test level places an increasing level of demand on the structural capacity of a barrier system. There is a need to evaluate the most common non-proprietary bridge rail systems used throughout the states to determine the level of evaluation required to demonstrate MASH compliance.
The objective of this research was to update the AASHTO LRFD Bridge Design Specifications and the AASHTO Roadside Design Guide for bridge rail geometric design for AASHTO MASH. The research included crash simulation and crash testing of the bridge railing systems that were found not satisfactory for the MASH equivalent test levels as documented in the NCHRP 20-07/ Task 395, "MASH Equivalency of NCHRP 350-Approved Bridge Railings".
STATUS: Final - The final report is available at Final Report

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