If you are looking for an explanation of K4 ratings, you have come to the right place.

K4 ratings are still referred to regularly, particularly in the APAC region (East Asia, South Asia, Southeast Asia, and Oceania), which can raise some confusion now that K4 ratings are used less frequently in the US and UK.

In 2003, DOS SD-STD-02.01 was released. This was an American impact testing standard released by the Department of State. K4 security ratings were one of 3 classifications: K4, K8 and K12.

Achieving a K4 security rating meant that the vehicle mitigation could stop a 15,000lbs American style vehicle at 30mph in under 50 feet.

In 2020, this security rating was replaced with ASTM F2656.

However, K-rated fencing is still being specified to protect critical infrastructure, specifically in locations such as Australia and Asia

In this blog, we aim to clarifying how the K4 rating influences modern high-security products, and how to know your product is suitable for hostile vehicle mitigation.


K4 And How It’s Still Referenced


Now, we know what you’re thinking.

If a modern-day product was tested to a K4 rating, is it still efficient in mitigating the risk of a hostile vehicle?


K ratings are no longer officially used or tested to but are still frequently referred to. They still refer to a product that has been crash tested by vehicles moving at significant speed.

Sound familiar?

That’s because although this security rating has been replaced, the purpose of the rating has stayed the same.

Just because a certain standard has been specified, it doesn’t mean that is the only standard that can be used.

Hostile vehicle mitigation is all about mitigating the risk of penetration from the vehicle – whichever standard you adhere to.


How Do I Know My Specification Is Still Valid?

It is important to remember that you can look at other standards, if you understand the risk they are trying to mitigate, and ensure you look for an equally accredited product.

What we mean by this is that it’s important to focus on what you are trying to mitigate, and ensure the standard matches this.

For example, StronGuard RCS is a fence that is impact tested against the PAS68 standard, able to stop a 7.5 tonne (16,500lb) vehicle at 30mph. This is equivalent to the K4 rating.  In fact, it actually stopped the vehicle in 3.5metres (11.5 feet) – well under the 50 feet allowed.

As long as your fence meets the following impact performance requirements, any specification is valid.

  • Vehicle Classification
  • Impact Speed
  • Impact Angle
  • Penetration Distance

Ultimately, this gives you access to a wider range of products to specify to mitigate your risk.


Finding Alternatives To K4 Security


Here at Barkers Fencing, we have previously been asked to provide a K4 rated fence in Australia.

Although we know that our products aren’t tested to the DOS standard, there are fences we can provide that meet the hostile vehicle mitigation requirements.

See the case study below for an example of this.


Case Study


In 2010, we were approached by an architect looking for a highly secure, third-party tested fencing system.

The fencing system would primarily be used to protect their clients high value data centres across the EMEA.

The data behind the security fence was incredibly sensitive, meaning that preventing an attack on the premises was paramount.

It was decided that palisade security fencing and gates that were NPSA (previously CPNI) accredited and approved for government use needed to be specified for this project.

The solution also needed to provide hostile vehicle mitigation, to ensure that a vehicle was unable to successfully drive into the premises.

Since 2010, Barkers have gone on to secure numerous data centres for this client around the world with StronGuard and StronGuard RCS (Barkers’ crash rated fencing). When a data centre arose in Australia, it was specified as K4 rated fencing as they often still refer to the DOS K ratings for impact standards.

As the PAS68 rating that StronGuard RCS achieves is equivalent to K4, Barkers supplied 5000 metres.




In the event of a vehicle attack, it’s crucial to be prepared with a fence that meets appropriate requirements.

K4 security ratings are no longer officially used but are frequently referred and still adhered to.

However, impact testing offers a varied selection of standards, meaning that just because a certain standard has been specified, it doesn’t mean that is the only standard that can be used.

Here at Barkers Fencing, we are always ready to help with any questions you have regarding crash-impact testing, and how to best protect your site.

Make sure to get in touch with a member of the team if you are specifying a security fence. Don’t let your questions go unanswered!