Manual for Assessing Safety Hardware (MASH)
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The AASHTO Manual for Assessing Safety Hardware (MASH) is the new state of the practice for the crash testing of safety hardware devices for use on the National Highway System (NHS). It updates and replaces NCHRP Report 350.
Testing criteria for highway roadside hardware have been in place since 1962. NCHRP Report 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features, has been the accepted method for safety hardware device testing and acceptance since 1993.
MASH presents uniform guidelines for crash testing permanent and temporary highway safety features and recommends evaluation criteria to assess test results. This manual is recommended for highway design engineers, bridge engineers, safety engineers, researchers, hardware developers, crash test laboratories, and others concerned with safety features used in the highway environment.
Why was change needed?
The need for updated crash test criteria was based primarily on changes in the vehicle fleet. Vehicles have increased in size and light truck bumper heights have risen since the NCHRP Report 350 criteria were adopted in 1993 (see chart for details).
How does this affect guidelines in the Roadside Design Guide?
MASH does not supersede any guidelines for the design of roadside safety hardware, which are contained in the AASHTO Roadside Design Guide.
What about products currently in development based on NCHRP 350?
Any new or revised highway safety hardware under development as of October 15, 2009, when the MASH was published, may continue to be tested using the criteria in NCHRP Report 350. However, FHWA will not accept or review requests for new or revised highway safety hardware tested using NCHRP 350 criteria which are received after January 1, 2011.
Why did the TL-3 test speed not increase above 100km/hr (62.2 mph)?
The FHWA Office of Safety considers that a 100 km/hr test is representative of worst case run-off-road crashes. Early on in the panel discussions related to the update of NCHRP Report 350, there was considerable discussion about the need to crash test at speeds over 100 km/h given that the posted speed limit of some highways is now above 65 mph. Based on data available to the research team it was concluded that, regardless of posted speeds, most impacts with fixed objects occurred at somewhat reduced speeds, likely due to pre-crash application of brakes.
When does our State have to switch to MASH-tested hardware?
There is no such deadline. The AASHTO / FHWA MASH Implementation Plan states that all highway safety hardware accepted prior to adoption of MASH using criteria contained in NCHRP Report 350 may remain in place and may continue to be manufactured and installed. Hardware tested under MASH should be considered for use within your State as it becomes available, but there is no requirement to replace hardware that has been accepted under Report 350.
For More Information
Purchase MASH report from the AASHTO Bookstore: https://bookstore.transportation.org
FHWA Presentation on MASH (October 2009): http://fhwa.na3.acrobat.com/mashfinal
FHWA website on roadside hardware: http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware
Roadside Design: Steel Strong Post W-beam. A guidance memo was issued on May 17, 2010 on the height of guardrail for new installations. Guidance regarding existing guardrail will be developed in the next several months, in consultation with AASHTO’s Technical Committee on Roadside Safety.