The AASHTO Technical Committee on Roadside Safety (TCRS) and 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. The FHWA will no longer issue eligibility letters for bridge rails that have not been successfully evaluated relative to MASH performance criteria.
There are many types of non-proprietary (generic) NCHRP 350 bridge rails in use throughout the states. With the recent adoption of a new joint AASHTO/FHWA implementation agreement, there is a need to review these current NCHRP 350 bridge rail systems and determine the level of evaluation required to demonstrate MASH compliance. NCHRP Project 20-07, Task 395, “MASH Equivalency of NCHRP 350-Approved Bridge Railings” is currently underway to evaluate the most common, highest priority railing systems such as concrete bridge rail systems (F-shape, single slope, vertical wall, etc.) with consideration given to different rail categories and features. It is fully anticipated that additional full-scale testing will be required for state DOT rail systems whose performance is uncertain and for which this proposed NCHRP project is dedicated to. The additional research is needed since it is anticipated that NCHRP Project 20-07, Task 395, will leave out many systems that will not be ruled eligible by FHWA and additional analysis and crash testing efforts will be needed to cover the common state DOT bridge railing systems. The results of each task become recommendations to AASHTO to serve as interims to all existing AASHTO Design Manuals (i.e., Geometric Design of Highways and Streets and LRFD Bridge Design Specifications).
The objectives of this research are to: (1) determine the remaining bridge railing systems to be reviewed and crash tested based on outcome of current NCHRP Project 20-07, Task 395, and literature search of any other state systems; (2) conduct LSDYNA Finite Element Analysis computer simulation as per NCHRP Web-Only Document 179, and crash testing of remaining state systems; (3) provide recommendations on these systems and request FHWA eligibility letters for MASH conformance as needed; (4) provide information to AASHTO TCRS, AASHTO SCOBS T-7, and state DOTs for their use; and (5) review/update existing FHWA Memorandum “Information - Bridge Rail Analysis” (dated May 16, 2000).