Note: This article was originally published as a sidebar within the “Advantages of Precast Concrete Barrier Systems for Perimeter Security” article, Precast Inc. July-August 2010.
By Sue McCraven
Which federal agencies require the K rating for safety barriers?
The U.S. federal agencies requiring crash barrier certification are Department of State (DoS); Department of Homeland Security (DHS); Federal Emergency Management Agency (FEMA); Department of Defense (DoD); and Transportation Security Administration (TSA ). Other federal and state agencies may only require that security barriers be capable of stopping vehicles for specific conditions or have ratings comparable to AST M or DoS standards.
What anti-crash certification for barriers is currently in force?
Since 2009, the DoS K ratings are no longer serving as the certification criteria. Currently, the AST M F 2656-07 standards are predominantly used for anti-crash certification of perimeter security barriers. All DoS K-rated barriers that were certified before 2009 are still recognized as equivalent to those meeting the corresponding AST M standard rating. For, example, a DoS K12-rated barrier is considered equivalent to the newer AST M F 2656-07 M50 designation.
Is there a preferred rating for security barriers in the United States?
There is no one standard rating of preference in the United States. Rather, the level of barrier rating required is dependent on the security importance of the building; surrounding traffic speed and approach patterns; and building exposure and blast standoff distance. For example, specific sides or corners of a building may require a higher rating, like K12, but other parts of the building may only require a K4 rating, which is a relatively low level of protection.
Because current testing only measures right angle (dead-on) vehicle impact, more stringent ratings are often required for the real-world potential for angular impacts. As a result, the K8 and K12 ratings are more commonly mandated for protection of important buildings and facilities, particularly in cases where the allowable blast stand-off distance is limited.
How do I obtain certification for precast barriers and how much does it cost?
A precaster must hire an accredited lab to perform an actual vehicle crash test. Accredited lab tests typically exceed $50,000 This cost includes test vehicle (truck) procurement and disposal; soil and foundation work; precast product installation and disposal; and instrumentation and labor fees. Computer simulations are less expensive, about $20,000, and can help predict barrier behavior and optimize design. Modeling avoids an expensive and unexpected failure in actual crash tests. Computer models can simulate various impact scenarios and provide very useful results for both the precast specifying engineer and the client (the lab used in the precast concrete barriers tested by the authors is KARCO Engineering, Adelanto, Calif.).
Is it true that the federal or state agency requesting bids for barrier protection is not always the property owner and that design and rating approval can involve a third party?
Yes. It is true that government agencies are not necessarily the building owners or managers. If the property owner is not the government RFP agency, a third-party owner or realtor manager must be involved in barrier planning, design and installation. The precaster and requesting agency will need to work together with the property owner in deciding on such issues as architectural appearance and pedestrian access.