What is Hostile Vehicle Mitigation? The Definitive Guide

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    As defined by the National Protective Security Authority (NPSA – formerly the Centre of Protection of National Infrastructure or CPNI), Hostile Vehicle Mitigation (HVM) is a protective security discipline focusing on reducing risks associated with vehicle-borne threats posed by terrorists and criminals.

    So, what are these potential risks? Outlined below are the seven main types of vehicle-borne attacks that need to be protected against (Source: NPSA):

    1. Parked: A vehicle containing an improvised explosive device (IED) is left in close proximity to an intended target. This vehicle might be parked completely legitimately so as not to raise suspicion. Equally, the vehicle may also be parked or abandoned illegally.
      An example of this kind of threat was seen in 2007 when two parked cars in London were discovered containing improvised explosives and fortunately were disabled before they detonated. This was also a common attack methodology used by the Irish Republican Army to detonate IEDs within prestigious areas.
    2. Encroachment:  A vehicle is utilised to exploit gaps in a site’s perimeter security. This could be by tailgating a legitimate vehicle through an access control point or by driving through an unprotected part of a perimeter. This might occur if security measures have not been correctly planned or implemented, equally if an attacker has insider information on security protocol which can be exploited. Encroachment-style threats can also include tampering with or weakening a security system in order to be able to gain access at a later date.
    3. Penetrative: This is where a vehicle is used as a tool to breach or weaken a building or physical perimeter. Typically, this kind of ram-raid attack has been used by criminals; however, it has also been adopted by terrorists. The attacking vehicle may also be carrying an IED and be detonated once inside, next to a physical target or near to a crowded place. The attack on the British Consulate in Istanbul, Turkey was a tragic example of such an attack.
    4. Deception: Commonly known as a ‘Trojan’ vehicle, a hostile vehicle may have been altered to replicate a legitimate vehicle, perhaps disguised in livery related to the site. Alternatively, the occupants may have used some other form of deception to bypass an access control point for example by obtaining or copying a legitimate ID. The vehicle may also be carrying an IED to target an area or a building.
    5. Duress: In attacks like this, a guard or employee could be forced to allow access to a hostile vehicle, or a driver could be forced to transport and park a VBIED near a vulnerable target under threat.
    6. Insider: An individual with legitimate access allows an assailant through security measures and helps to facilitate a security breach or attack. This could also include tampering with a security measure to allow access for an intruder.
    7. Tamper/Sabotage: Facilitating a hostile vehicle attack by tampering with or sabotaging a security barrier or measure prior to a planned attack to make access easier or possible. Tampering with the intent of leaving no evidence and avoiding raising suspicions prior to an attack being carried out.

    The Purpose of Hostile Vehicle Mitigation

    Hostile vehicle mitigation (HVM) measures are used to protect people and buildings from potential vehicle threats. Often HVM measures will be employed around crowded public areas or critical national infrastructure sites such as government buildings, data centres or power stations.

    There are two major types of vehicle threats that HVM measures are used to protect against – Vehicle Borne Improvised Explosive Devices (VBIED) and Vehicle as a Weapon (VAW). As you’ll see, in recent years the focus has shifted from a complete focus on preventing VBIED attacks to protecting against the emerging VAW threat as attacker methodology seems to have evolved. Both threats must still be considered.

    Vehicle-Borne Improvised Explosive Devices (VBIED)

    Vehicle-borne improvised explosive devices (VBIED) refer to any improvised explosives that are delivered using a vehicle. You may more commonly hear them referred to as car bombs, lorry bombs or truck bombs. According to the US Department of Homeland Security, there are several reasons why VBIEDs make for an effective weapon for terrorists:

    1. The number of explosives able to be employed.
    2. The ease of placing the explosives close to a target without raising suspicion.
    3. The potential to inflict mass casualties and/or significant structural damage.

    In 2016, the Iraqi capital Baghdad, saw one of the worst VBIED attacks in history, as a lorry packed with explosives detonated in the Karrada district killing 323 people. A year later another horrific attack took place in Kabul, killing 150.

    Despite the presence of blast protection, several Embassy buildings sustained damage in the attack. Both incidents as well as many more in recent history, illustrate the very real threat posed by VBIED attacks.

    One of the most important concepts in protecting against VBIEDs is the idea of ‘standoff’; the distance able to be created between the asset or area being protected and the location of the explosion from a potential VBIED attack, usually at the perimeter of the intended target.

    The effect of the blast needs to be considered when protecting against VBIED attacks. When it comes to explosions the most effective tool for mitigating blast effects is to ensure that the explosion occurs as far away from the asset as possible, providing enough of a chance for the bomb blast to dissipate, minimising destruction and damage to the target and surrounding area.

    There is no single ideal stand-off distance, instead, this is determined by several factors such as:

    • The type of threat
    • The construction and materials of the building
    • Land ownership parameters
    • The desired level of protection.

    For instance, when assessing a military base, the main gate or entrance may be 50m(+) away from the main infrastructure it is securing In this instance, creating a stand-off distance is not a problem. When looking at an alternative scenario in the middle of a city centre where a high-profile financial asset is situated on a piece of land with only one meter between the asset and the asset’s perimeter, stand-off creation is impossible.

    Secure measures chosen in this scenario would need to dead-stop a vehicle at the perimeter with under 1 meter of penetration, to avoid the hostile vehicle from entering the heart of the building itself and detonating an IED.

    The diagram below illustrates a stand-off zone between a threat and an asset.

    Vehicle as a Weapon (VAW)

    In recent years, a new threat has emerged – ‘vehicle as a weapon’ attacks. This rise has been witnessed in the tragic events at Nice, attacks carried out on both Westminster and London Bridge, Berlin and many more European cities.

    This is partly due to the difficulty in obtaining the materials needed to assemble an IED and the ease at which individuals can hire large vehicles.

    Unless a terrorist draws attention to themselves in any way or prior intelligence is gathered on a suspect’s movements, vehicle-as-a-weapon-attacks can be hard to anticipate.

    Whereas VBIED attacks target critical national infrastructure and high-profile sites/areas, vehicle-as-a-weapon attacks directly target crowds of people in busy public spaces, using infrastructure such as bridges and main tourist promenades.

    Since the attacks in the UK, the British government has released guidelines for goods vehicle operators and drivers to help guard against VAW.

    The guide covers three main areas to be aware of: security culture, site security and vehicle security.

    To physically protect against this emerging threat, recent HVM product development has been focused temporary HVM security measures, such as ATG’s Surface Guard Barriers. This allows for temporary events to be protected, such as fan zones, concerts, Christmas markets and festivals, as these measures can be rapidly deployed prior to an event and removed afterwards when there is no longer a threat.

    Types of Hostile Vehicle Mitigation Products

    When selecting HVM measures, the National Protective Security Authority (NPSA – formerly the Centre of Protection of National Infrastructure or CPNI) recommends that any physical security measure to protect against vehicle threats be appropriately certified for use.

    This means that it must have been tested to a recognised vehicle impact test standard, performed by an independent test house and achieved a performance rating in line with the impact test standard.

    Hostile Vehicle Mitigation Bollards

    Bollards are generally the preferred form of passive HVM measure within busy sites located in the public realm such as squares and transportation hubs as they allow for pedestrian permeability. This is important when blending security measures into crowded, urban environments as the flow of pedestrians and authorized traffic must be maintained and not hindered.

    Bollards are also the first choice when being installed within a public UK highway as their aesthetic is less obtrusive when compared to a road blocker or arm barrier solution, blending into the surrounding environment and avoiding the creation of a fortress mentality.

    Hostile vehicle mitigation bollards and barriers will often have been crash-tested to one or more of the major crash test standards currently in place.

    These are BSI PAS 68 (UK), ISO IWA 14-1 (International) and ASTM F2656 (USA). If you would like to learn more about PAS 68 or IWA 14, or other crash-ratings standards, we recommend reading our crash-rating guides to get a more in-depth understanding of them.

    If you’re looking for more information on counter-terrorism measures such as HVM bollards, we recommend reading our blog post “What do we mean by HVM Bollards?”, which gives a more in-depth look at these measures.

    Hostile Vehicle Mitigation Barriers

    Hostile vehicle mitigation barriers tend to come in two types: permanent HVM barriers, which are predominantly used in securing critical national infrastructure and portable hostile vehicle mitigation barriers, which are used to protect events and crowded spaces such as Christmas markets and festivals temporarily.

    Permanent hostile vehicle mitigation barriers will often be used to control an access point or secure a perimeter.

    Products for access control can be automatic or manually operated. These can come in various types, such as beam barriers, swing gates and manual arm barriers to name just a few, each with its own benefits and ideal applications.

    For perimeter security, industrial and military sites generally use high-security fencing or wire-rope systems to secure long-span perimeters. This method also keeps people, as well as vehicles, out – which might be the objective for a data centre or a military base – whilst allowing approved access via the secured access point for vehicles and pedestrians. For urban areas such as transportation hubs and financial districts, pedestrian foot flow is encouraged and so, in this instance, bollards or impact-tested street furniture products might be preferred to ensure a welcoming aesthetic.

    If you would like to learn more about hostile vehicle mitigation as a whole, we recommend reading the National Protective Security Authority (NPSA) guide.

    If you need any advice on impact-tested products or have any questions regarding IWA 14, PAS 68, or ASTM, then contact one of our experts on +44 (0) 345 350 3799 and they’ll be more than happy to help.