What is PAS 68? The Definitive Guide to PAS 68

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14 Dec, 2020

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    14 Dec, 2020

    What is PAS 68?

    PAS 68, (now replaced by ISO 22343) was produced by the British Standards Institution (BSI) as a publicly available specification (PAS) for the impact testing and certification of products intended for hostile vehicle mitigation (HVM) such as bollards, road blockers and vehicle barriers used for securing assets and infrastructure against hostile vehicle attacks.

    In the world of physical security, the PAS 68 specification is something many will already be familiar with.

    In the UK it was the de facto test standard for hostile vehicle mitigation, but for those outside the industry, PAS 68 is either unknown or not fully understood.

    What does PAS 68 stand for?

    PAS stands for ‘Publicly Available Specification’ and PAS 68 is one of the many standards produced by the British Standards Institution (BSI).

    PAS 68 was originally drawn up in 2005, becoming the first British impact test specification. Recognised as one of the premier crash test specifications around the world, PAS 68 has played an integral role in shaping subsequent impact testing methodologies feeding into standards which have followed.

    Since its original development, PAS 68 went through several variations, with 2013 being the last. To be used in conjunction with BSI PAS 69, its sister standard, this is just as important, supporting PAS 68 in ensuring the effectiveness of the installation of high-security products.

    What does the PAS 68 rating mean?

    A common misconception is that PAS 68 relates to only one type of test and that a product is either certified to PAS 68 or it is not. In fact, the PAS 68 certification covers a wide range of different rating types which vary depending on the type of vehicle and the vehicle speed specified within a test. This is varied to capture a range of different risk profiles sites may have.

    Factors such as the size of the vehicle tested and the target speed at which the attacking vehicle is travelling help end users decide which PAS 68-certified product is best suited to mitigate a specific threat profile.

    That, of course, means understanding your site’s threat profile. We strongly recommend that site owners/operators seek independent and appropriate advice in doing so. If a site is deemed vulnerable to vehicular attack, a Vehicle Dynamic Assessment (VDA) should also be carried out.

    Given the highly technical nature of this kind of assessment, it should only be carried out by an appropriately qualified Counterterrorism Security Advisor, consultant, or Engineer accredited by the RSES (Register of Security Engineers and Specialists).

    Test Method

    A PAS 68 rating is made up of component parts (numbers, letters, and symbols) each denoting specific elements of the test itself and the vehicle used, including test method, vehicle type, test speed, impact angle, impact penetration and debris dispersion.

    Those different elements make up a complete string like the example below, which we will break down to help you understand what each part means:

    The initial letter in the test (in this case “V”) indicates what type of test has been carried out:

    • V – Vehicle – an actual vehicle of defined mass and size impacts the product under test conditions. This is the most common method you will find.
    • D – Design (simulated test) – a calculated or computer-simulated result is derived.
    • P – Pendulum – a fixed mass attached to a swinging arm (pendulum) is used to deliver the impact against a product.

    Vehicle Type

    Next up is the mass and type of vehicle. The weight is measured in kg, so in our example, it was tested with a 7,500kg vehicle. Then, the (N2) refers to the vehicle category. A more detailed breakdown of the different vehicle types can be seen below. With N2 and N3 vehicles, one is 7,500kg while the other is 7,200kg laden with ballast.

     

    As you can see, a variety of vehicles may be used for the impact test. Therefore, the testing method should not be overlooked.

    Note: Where the “design” method is used, it is vital that the calculation or simulation method is validated by real-world data taken from physical tests, preferably on close iterations of related products. A sensible example of this in practice would be an HVM gate tested at 4m width and 8m width. It may be appropriate to apply design testing methodologies to a 6m gate or even an 8.5m gate. But it would be less appropriate to draw the same design-lead conclusion to a 12m gate.

     

    Test Speed

    After that, we have the test speed, which is measured in kilometres per hour (kph). So, looking at our example rating, we see that it was tested at 48kph.

    Typical target speeds you will find are:

    • 32kph (20mph)
    • 48kph (30mph)
    • 64kph (40mph)
    • 80kph (50mph)

     Impact Angle

    The next section gives you the impact angle of the test.

    Most commonly, this with be 90°. Products may also be tested for different angles of impact, which may be appropriate for special applications, for example, in bridge protection, where the possible angle of attack is limited.

    Impact Penetration / Vehicle Penetration

    Impact penetration measures how far the load-carrying part of the vehicle travels past the product before coming to a complete stop.

    The distance is measured in metres from specific datum points on the vehicle and the product.  This datum line can be seen in the graphic below.

    In this instance, the value is 0m. In detail, the datum point on the vehicle is the leading edge of the load carrying part and the datum point or datum line on the product is simply defined as the back face of the product.

    The datum point on the product differs from both ISO 22343 and IWA 14, so care must be taken when comparing products that have different ratings.

    In our example, the bollard achieved 0m penetration. The level of penetration considered acceptable depends on where the perimeter line is in relation to the asset being protected. The distance between the protected asset and the protective measures line is known as “stand-off”.

    Debris Dispersion

    Finally, we have the dispersion distance of major debris. This measurement indicates the furthest point that debris weighing over 25kg travelled during the test.  In the case of our example rating, it had a dispersion distance of 0.

    This is included to help security engineers visualise the test and should not be a focal point for end-users. This has caused some confusion in the past, resulting in the IWA 14 standard not including the dispersion distance measurement.

    What about the other impact test standards?

    Now that you know a bit more about PAS 68, you may be wondering about the other impact test standards.

    The latest impact test standard is ISO 22343 – this is set to become the de-facto test standard for HVM products and supersedes PAS 68.

    The other most common impact rating listed on our high-security bollards, blockers and barriers is the IWA 14 standard (our Centurion Shallow Mount Bollard is a great example).

    Released in 2014, the International Workshop Agreement (IWA), follows a similar structure to PAS 68, with two key differences:

    • Firstly, the penetration measurement is taken from the front face of the product being tested and not the back face.
    • Secondly, debris dispersion is not recorded.

    The final rating you may come across is DOS, an American rating. This has now been superseded by ASTM (American Society of Testing Materials).

    A more recent addition is PAS 170 which is designed for low-speed impact testing bollards using an impact trolley. You can find out more in our PAS 170 guide.

     

    Download Our Physical Security Standards E-Book (now including ISO 22343)

    With the release of ISO 22343 in September 2023, the experts here at ATG Access have updated our popular ‘Guide to Physical Security Standards eBook’ to include details on the new standard. The latest edition of the guide explains the differences between the old and current standards and goes through an example test result step-by-step to help you understand the new standard.

    Complete the form below to claim your free copy.