NCHRP 350 & MASH

NCHRP 350 and MASH represent 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 and MASH include longitudinal barriers, transitions, end terminals, crash cushions, 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 and MASH. Note that NCHRP 350 has been rewritten under NCHRP Project 22-14(02). Click here for details.

MASH has been adopted and published. Click here to see a summary of the differences between MASH and NCHRP 350 and the AASHTO/FHWA joint implementation plan.

Rewrite of NCHRP 350

The rewrite of NCHRP 350 is completed. It was reviewed by the AASHTO Technical Committee on Roadside Safety (TCRS) and is an AASHTO document. It's called The AASHTO Manual for Assessing Safety Hardware (MASH). This rewrite updated the test vehicles, the impact condition criteria, and the evaluation criteria. The differences between MASH and NCHRP 350 along with the AASHTO/FHWA joint implementation plan can be seen at the above link.

MASH

The NCHRP Report 350 crash testing and evaluation criteria has been updated and the new publication is called MASH, The AASHTO Manual for Assessing Safety Hardware. As part of the rewrite of NCHRP 350, there were three main focus areas:

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

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.

FHWA Memos

Click here for important Grading & Length of Need information

 

Historical Review

Document Source Year Issued # of Pages Test Vehicle & Weight
HRB #482 1962 1 4400 lb. car
NCHRP #115 1971 70 4000 to 5000 lb. cars.
NCHRP #118 1972 96 2000 & 4500 lb. cars
NCHRP #153 1974 19 2250 & 4500 lb. cars
TRC #191 1978 27 *2250 & 4500 lb. cars
NCHRP #230 1981 42 *1800 & 4500 lb. cars
NCHRP #350 1993 132 *1800 lb. car &
4400 lb. Pickup

*Large trucks also considered

 

Test Vehicles

NCHRP 350 Test Vehicles For Barriers Test Vehicle Mass Location of Vehicle Center of Mass
Small Car 1800 lb.
(820 kg)
21.7 in.
Pickup Truck 4400 lb.
(2000 kg)
27.6 in.
Single-Unit Van Truck 17,650 lb.
(8000 kg)
66.9 in.
Tractor Van Trailer (TL-5) 79,400 lb
(36000 kg)
72.8 in.
Tractor Tank Trailer (TL-6) 79,400 lb
(36000 kg)
80.7 in.

 

Test Levels for Barriers

NCHRP 350 Test Level For Barriers Largest Vehicle Mass Large Vehicle Impact Speed Impact Angle for Barriers
TL-1 4400 lb. (2000 kg) 31 mph (50 km/h) 25 deg.
TL-2 4400 lb. (2000 kg) 43 mph (70 km/h) 25 deg.
TL-3 4400 lb. (2000 kg) 62 mph (100 km/h) 25 deg.
TL-4 17,650 lb (8000 kg) 50 mph (80 km/h) 15 deg
TL-5 & TL-6 79,400 lb (36000 kg) 50 mph (80 km/h) 15 deg.