The DOD Anti-Ram Vehicle Barriers: July 2018 document adds several new barriers and adds two new aspects of defensive geometry.

• “interpolated” designs where a barrier is tested for openings of 10′ and 20′ and is also approved for in between distances. such as 13′.
• designs where a barrier is only able to be used for a particular engineered distance such as 20′.  This is challenging if your site doesn’t work in neat 10′ or 20′ increments.

To create this standard, the DoD employs an ASTM International performance standard and testing procedure for both active entrance barriers and passive perimeter barriers designated as “vehicle-impact rated barriers,” or “anti-ram barriers.” The current standard is ASTM F2656-07, Standard Test Method for Vehicle Crash Testing of Perimeter Barriers.

The ASTM F2656-07 test standard rates barriers in twelve impact categories, with three predetermined impact velocities for each category and four potential penetration ratings for each impact rating. These penetration ratings are: P1 – < 3.3 ft; P2 – 3.31 to 23.0 ft; P3 – 23.1 to 98.4 ft; and P4 – > 98 ft.

A few characteristics to consider are listed below (list taken from the DoD’s Protective Design Center – unlimited distribution):

• Impact speed at barrier (low speed impact): The use of some vehicle barriers
  presented in this list exhibit vulnerabilities when impacted at speeds other than
  those associated with the ASTM and DOS test impact velocities.
• Design Basis Threat (DBT) vehicle, other vehicle weights and speeds: The barriers
  presented in this list have been subjected to impacts under the specific conditions
  prescribed by the test designation. If the Installation’s DBT includes vehicles
  significantly different than the test vehicle, performance of the system may differ
  from what may be expected.
• Deployment mechanisms: The mechanisms used to deploy vehicle barriers vary
  (pneumatic, hydraulic, electro-mechanical, manual). The various mechanisms
  should be investigated and the choice should be based on the best fit for the
  Installation.
• Environmental condition at barrier: Environmental conditions can vary greatly
  from location to location. Conditions such as rain, snow, ice, sand, gravel, hot, and
  cold need to be considered when selecting a barrier for a specific location.
• Operations and Maintenance (O&M) requirements: Each barrier comes with its
  own operational and maintenance requirements. The O&M requirements vary in
  the amount and intensity from barrier to barrier. O&M needs to be figured into the
  overall life cycle cost of the barrier.
• After impact barrier gaps: Post impact gaps may be an inherent characteristic of the
  barrier system. The barrier system’s post-impact condition should be carefully
  evaluated for its cap