NCHRP 350 represents uniform guidelines for conducting full-scale crash tests for permanent and temporary highway safety features along with recommended evaluation criteria to access the test results. Products addressed in NCHRP 350 include longitudinal barriers, transitions, end terminals, crash cusions, breakaway/yielding supports, truck mounted attenuators and work zone traffic control devices. The crash performance is judged on structural adequacy, occupant risk and vehicle trajectory. The in-service evaluations of these devices are also addressed in NCHRP 350.

Note that NCHRP 350 has been rewritten under NCHRP Project 22-14(02).
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Rewrite of NCHRP 350

The rewrite of NCHRP 350 is completed and being reviewed by the AASHTO Technical Committee on Roadside Safety (TCRS). It will be an AASHTO document and the "proposed" name is AASHTO MASH (AASHTO Manual for Assessing Safety Hardware). This rewrite updated the impact condition criteria, the evaluation criteria and the test vehicles. The crash test vehicles used in NCHRP 350 are no longer being produced and heavier vehicles will be used. The expected publication date is 2009. At that time, the implementation process will begin from the FHWA and the DOT perspective.

It is anticipated that FHWA will establish a deadline date as to when newly crash tested devices will need to be tested to the update criteria. As it stands now, immediately upon publication, any new devices, including any modifications and/or revisions to NCHRP 350 compliant devices, will have to be crash tested under the new AASHTO MASH. However, if a NCHRP 350 test program has already begun, that program may continue and results may be submitted to FHWA prior to January 1, 2011.

It is expected that each of the State DOT's will be able to set their own implementation dates and criteria. If that continues to be the case, each State will have the option of continuing to use 350 compliant hardware or establishing their own deadline for compliance with MASH. The States may elect to allow devices that have met NCHRP Report 350 criteria to stay in place.  The States may also elect to continue to allow devices that have met NCHRP 350 installed indefinitely. The States will announce their policies as they are developed. The NCHRP 350 devices will not be grandfathered as meeting the new criteria but will always remain identified as NCHRP 350 devices unless re-tested and passed under the new criteria.

MASH

The NCHRP Report 350 crash testing and evaluation criteria has been updated. The new publication will be called MASH, Manual for Assessing Safety Hardware.

As part of the rewrite of NCHRP 350, there were three main focus areas:

1. Test Vehicles were updated to what’s being produced and sold today.
2. Impact Condition Criteria were modified to correct inconsistencies and identify needed conditions.
3. Evaluation Criteria were modified to correct subjective criteria and better define other criteria.

Up to now, previous crash testing guidelines were published as NCHRP documents, but MASH will be an AASHTO document. This will allow the state DOT’s more control of the implementation and approval processes.

Here are some of the more significant changes from the NCHRP 350 conditions to the new AASHTO MASH conditions:

• Pickup truck increases from 4,400 lbs. to 5,000 lbs.
• Small car increases from 1,800 lbs. to 2,420 lbs.
• Small car impact angle changed from 20 to 25 degrees.
• Terminal & Crash Cushion impact angle changed from 20 to 25 degrees.
• TL-4 truck increases from 17,600 lbs. to 22,000 lbs.
• TL-4 truck speed changed from 80 km/hr to 90 km/hr.