‘Anti-terrorism’ bollards, blockers and other security barriers intended to protect against hostile vehicles are a common sight in many cities around the world. What began as temporary military measures implemented in high-threat environments has evolved into often permanent barriers around publicly accessible locations all over the world. But why are they used and when did it all begin?
Hostile Vehicle Mitigation (HVM) is a security discipline encompassing the physical security measures designed to prevent vehicles from being used as weapons against people, buildings, or infrastructure.[1] In the context of organised criminality and direct-action protests, the targeting tends to relate more to the use of vehicles to penetrate into target sites to facilitate a hostile action such as theft or sabotage. In the terrorism context, the threat relates primarily to vehicle ramming attacks and vehicle bombings (AKA vehicle borne improvised explosive device, VBIED attacks) – a particularly high-impact tactic.
The primary purpose of HVM measures are to keep hostile vehicles from getting to within a certain distance of the protected site or space at which they could do the most harm. This is known as ‘stand-off’, and is a core principal of HVM as every meter of distance between an explosive device at its target can be the difference between life and death. Additionally, a target can be protected by other methods, such as preventing hostile vehicles from being able to gain the speed necessary to penetrate into a site. In some environments, it is also necessary for the HVM measures to be capable of not only deterring, but also mitigating attacks by resisting the force projected against them by a hostile vehicle, as demonstrated in the image below.
Threat actors have used motor vehicles for attacks as far back as the early 1900s, at a time when there were also even attacks using horse-drawn wagons packed with explosives. However, it was the use of VBIEDs by paramilitary organisations, such as the Provisional IRA in Northern Ireland in the early 1970s that prompted the first organised attempts to protect checkpoints and vulnerable sites using heavy concrete blocks. The blocks and planters deployed by Security Forces (namely the British Army, working closely with the Royal Ulster Constabulary), were rudimentary and unrated, but generally effective as a deterrence measure, though attacks continued. At this early point, vehicle security barriers (VSBs) – the general term for the barriers used for hostile vehicle mitigation – were often deployed on a temporary basis: to protect specific locations while deemed to be at particular risk.
By the 1980s, terrorist groups also began increasingly using VBIEDs in Western Europe and the Middle East, often with devastating impact. Diplomatic missions, host nation government buildings, military bases, police stations and religious institutions all experienced VBIED attacks using different vehicles, from motorcycles to vans to heavy goods vehicles. The deadliest of these attacks was in 1983, when terrorists initiated two truck bombs at a marine barracks in Beirut, Lebanon, killing approximately 305 people – mostly US and French military personnel.[2] The size of the vehicles enabled them to carry huge explosive payloads, and the secondary device made the attack even more deadly. In the same year, terrorists also conducted a VBIED attack at the US Embassy in Beirut, killing 63 people. The devastating attacks on people, facilities and assets in the Middle East prompted efforts to deploy barriers capable of withstanding forceful impact from hostile vehicles, of which there did not yet exist tested and certified products. Consequently, concrete blocks and Jersey barriers – developed to securely separate two-way traffic on US roads – were widely used as a protective security measure against hostile vehicles due to their relative ease of deployment and cost. The attacks also prompted the creation of the first ever vehicle security barrier standards by the US Bureau of Diplomatic Security, who introduced the US DoS SD-STD-02.01 standard.[3] This standard specified impact ratings and penetration distances for VSBs, helping to provide assurance that barriers deployed would be capable to mitigating certain types of vehicular threats.
The 1990s marked a significant shift in threat perception in the US and UK, where huge economic damage and loss of life was caused by several high-impact VBIED attacks. The 1993 World Trade Centre bombing, in which a 603-kilogram VBIED was initiated below the North Tower of the WTC, highlighted significant vulnerabilities in urban infrastructure at the centre of the US economy. In the UK, the Provisional IRA conducted a campaign of terrorist attacks on primarily economic targets on the mainland, including VBIED attacks which caused extensive damage and huge economic cost. This campaign prompted UK security authorities to begin systematically evaluating vehicle-borne threats in urban centres and implementing permanent HVM measures protecting vulnerable and critical locations such as Westminster, the City of London, and Canary Wharf. In 2004, the UK established the National Barrier Asset – deployable security barriers to protect against VBIEDs and vehicle-as-a-weapon attacks.[4] With the growth of HVM installations, it was also deemed necessary to establish national standards for barriers, and in 2005 the British Standards Institution introduced PAS 68, which established rigorous testing protocols for VSBs.
The 9/11 terrorist attacks in 2001 were arguably the single most significant and consequential attacks, both for the transformation of the global security profession and industry, and more specifically, for the HVM discipline. While the attacks themselves did not involve hostile motor vehicles, the weaponisation of conventional transportation with such impactful consequences led to widespread reassessment of the threat that vehicles could pose in urban environments. In the US, the Government began mandating crash-rated barriers around Federal Government buildings, and large corporations and organisations invested heavily in HVM to protect their head offices and other major sites.
Since 9/11, both Europe and the US has experienced multiple high-profile vehicle-as-a-weapon (VAW) attacks that have continued, or perhaps accelerated, the adoption of HVM within publicly accessible urban spaces. The 2016 Nice attack was particularly deadly, killing 68 and injuring over 430 people, and Berlin, London, Barcelona, Stockholm, New Orleans and other cities have also experienced attacks using similar attack methods. The main similarities have been the presence of attractive targets in large numbers, a suitable location and the absence of adequate HVM, creating opportunities that have been exploited by motivated and sufficiently capable terrorists.
In response to the continued threat from the hostile use of vehicles, HVM technology has advanced and gradually diversified. While fixed and rising bollards and road-blockers are still generally the most common type of barrier found, there has been an increase in the use of concrete planters and other solutions that double as greenery or have another regular purpose and can therefore blend into an environment unnoticed, limiting the visual impact. For example, manufacturers now offer benches, lampposts, bins and bicycle stands that can all be constructed to meet HVM standards.
The market for temporary and quickly deployable mobile VSBs has also grown, with the need to protect publicly accessible and crowded spaces, such as town centres and areas hosting large events. Consequently, some local authorities now operate their own deployable VSBs, and many private companies exist that offer VSB products rentals. However, one of the most common methods still chosen, though not crash-rated, is often to either deploy basic multi-purpose concrete blocks or to park heavy vehicles blocking roads leading to the protected location. Aside from cost and availability, one of the key benefits of using such methods is that they can often by moved aside very quickly, for example to let emergency vehicles enter a protected area during an emergency.
Today, the trend continues to be towards integration of VSBs with other security technologies (such as access control and video surveillance systems) and proactively designing-in HVM through landscaping and street furniture, when urban spaces are being created or redeveloped. The terrorism threat main concern in European cities is currently with low-sophisticated attack methods such as VAW attacks, which require less capability and planning. However, as is often the way in the history of security: it is likely that threat actors’ methods will evolve over time and that new vehicle-based attack methods are developed, requiring new HVM tactics in response.
[1] https://www.npsa.gov.uk/specialised-guidance/hostile-vehicle-mitigation-hvm
[2] https://2021-2025.state.gov/40th-anniversary-of-the-beirut-marine-corps-barracks-bombing/
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