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Manufacturer of anti-terrorism vehicle access control barriers and conventional access control gates

How is a vehicle barrier's stopping power certified?

Barriers are certified by crash testing full-scale prototypes at one of a handful of authorized test facilities in the U.S.  The U.S. Department of State (DOS) released the first vehicle barrier certification standard in 1985.  They created the standard because many embassies were in historic buildings built close to the streets, and thus were susceptible to vehicle-based attack. 


That standard used a medium-duty commercial truck loaded to a total weight of 15,000 pounds and crash tested at 30, 40, or 50 miles per hour (mph).  Based on how far the vehicle penetrated beyond the impact point, the barrier received a letter and number rating as follows:


U.S. Department of State 1985 Barrier Certification Standard


 Speed at Impact  Speed Rating Penetration Distance  Penetration Rating
 30 mph K4 < 3 ft L3 
 40 mph K8  3 - 20 ft L2
 50 mph  K12  20 - 50 ft L1


For example, if a barrier stopped a 15,000-pound truck traveling at 40 mph and the truck penetrated six feet beyond the impact point, the barrier received a K8/L2 rating.


The standard was tightened in 2003 when the DOS decided that any vehicle that penetrated more than 3 ft. would fail certification, thus the “L” ratings for penetration distance was eliminated and only the “K” ratings remained.  This was a disservice to users of portable barriers.  Those barriers dissipate the vehicle’s impact energy by sliding along the ground, thus they could no longer be certified.

Recently ASTM International, formerly the American Society for Testing and Materials, has taken on the responsibility for vehicle barrier certification standards.  They kept essentially the same rating designation as the DOS, but added several more vehicle weight (mass) and speed categories, and also reincorporated the penetration distance allowances.

It is important to recognize that both the DOS and the newer ASTM standards are based on a vehicle’s kinetic energy (hence the “K” rating in the original 1985 standard).  Kinetic energy = ½MV2 so a vehicle’s speed is the dominant factor in determining its impact energy.  The following vehicles traveling at the listed speeds all have about the same kinetic energy:


 Vehicle Type  Vehicle Weight
 Vehicle Speed (mph)
2,400  125
light truck  5,100 85
medium truck 15,000 50
heavy truck  65,000 25
locomotive 200,000 15
train 10,000,000 2

Thus, any barrier that is rated K12 (DOS standard) or M50 (the equivalent ASTM standard) is capable of stopping any of the above vehicles traveling at the listed speed.  And if some amount of penetration distance is acceptable, then the K12 (M50) barrier can stop the above vehicles even if they are traveling at higher speeds.


    The certification
crash test of our
Arrestor model


Because conducting a full-scale crash test of a new barrier is so expensive, some barriers are rated to an ASTM or DOS standard rather than certified to that standard.  This means that the designers have calculated the barrier's capability based on previous experience and tests, but have chosen to forego the actual crash test.  PRO Barrier Engineering’s LightFoot barrier is a rated barrier.  Its design is based on the Arrestor barrier (which is certified K12) but it is rated at K4 because it has less energy absorbing material and a shallower foundation depth. 


A big disadvantage to a certified barrier is that once certified, the design cannot be improved and retain its certification without conducting another full-scale crash test.  In contrast, rating a barrier allows us to continuously improve the design without having to pass along the expense of additional crash tests to our customers.  


Contact Us if you would like further information regarding vehicle barrier certification and the newest ASTM crash test standard or return to FAQs.