Managing Editor, IFSEC Insider

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James Moore is the Managing Editor of IFSEC Insider, the leading online publication for security and fire news in the industry. James writes, commissions, edits and produces content for IFSEC Insider, including articles, breaking news stories and exclusive industry reports. He liaises and speaks with leading industry figures, vendors and associations to ensure security and fire professionals remain abreast of all the latest developments in the sector.
June 28, 2023


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The purpose and benefits of a Vehicle Dynamic Assessment

The growing and elusive threat of lone actor vehicular terrorism is prompting organisations across the UK to update or implement Hostile Vehicle Mitigation (HVM) solutions, perhaps for the first time at many sites. Lucy Ketley, Sales and Marketing Director at ATG Access and Chris Stevens, Specialist Security and Risk Director at SIDOS, provide IFSEC Insider readers with an overview of Vehicle Dynamic Assessments, their purpose and key considerations when looking to carry one out.


Lucy Ketley, Sales and Marketing Director, ATG Access

This calls for fresh threat and vulnerability assessments, and experts from the CPNI to HVM counter-terror consultants say that a Vehicle Dynamic Assessments (VDA) is the necessary starting point. A VDA is a long-established technical component of HVM and essential to specifying a robust and appropriate defence for vulnerable targets.

So, why is it that some clients choose to forego a VDA? Clients know a VDA is important, but perhaps not quite how important and the extent of its added value.

In this article, we explore the importance and value of VDAs in detail and explain why it is always a worthwhile investment.

Editor’s note: CPNI (Centre for Protection of National Infrastructure) was absorbed into the newly created National Protective Security Authority (NPSA) in March 2023. 

Choosing your Vehicle Dynamic Assessment scope and skills

A Vehicle Dynamic Assessment (VDA) is one part of an extensive, specialist process to procure Hostile Vehicle Mitigation (HVM) measures. A VDA assesses threats and vulnerabilities at multiple access and entry points around project sites, crowded spaces and other infrastructure.

Before heading into a VDA and engaging with an advisor, it is crucial to establish a clear scope of VDA requirements to ensure the right level of risk is mitigated. (i.e., locations? is it for counter-terror purposes only, crime prevention, or both? and what threats and vulnerabilities exist per site?).

If you need support achieving this, look for professional organisations experienced in delivering VDAs in a HVM, counter-terror context. Ideally, their capability should come on recommendation, too. The same credentials should apply to the specific individual who’ll eventually conduct the VDA.

Formal VDA scoping will be unfamiliar or new to most clients or project managers. It’s essential that it’s complexity and criticality are appreciated and that all stakeholders are clear on the importance of preliminary scoping. After all, it is a precursor to every HVM decision made thereafter.

Beginning the Vehicle Dynamic Assessment process

A VDA may be your first advisory step in a security scheme or the progression of a process already in hand. Depending on breadth of knowledge, experience or project immersion, you may choose to undertake a VDA yourself – as a CTSA or Tier 1 Site Risk Manager, for example – or commission a specialist security consultant.

Regardless of the stage you are currently at, it is wise to familiarise yourself with VDA associated liabilities. In short, whoever provides HVM advice post-VDA is liable for the recommendations made should HVM fail.

Is a VDA required?

Often, there is a very clear case for a VDA on the basis that HVM is already a consideration in a scheme. But there is always a possibility that the clients for whom you work (or perhaps you are the specifying company?) won’t know that HVM is required or how to begin the threat identification process.

In these cases, it is recommended that a threat and vulnerability assessment is undertaken ahead of a VDA. This is also true for any sites where HVM demand has not been identified, but the landscape is changing. i.e., you may have three sites in a project of which two have never been threat assessed. At this point you should:

  • Undertake a risk assessment for each location in a project
  • Determine the threats and vulnerabilities facing each location
  • Work with someone experienced with HVM in a counter-terror context

But, assuming the need for HVM has been identified, a VDA should follow and broadly speaking will consider the following elements:

  • Existing security measures, procedures and practices
  • All potential routes a vehicle could negotiate to the point of contact
  • The size of vehicle that could negotiate said route, i.e., width
  • The speed a vehicle could achieve along that route
  • The weight of vehicle that could negotiate the route, i.e., 3.5 tonne, 7.5 tonne, 7.5 tonne laden to 18 tonne, or fully laden HGV at 30 tonne

How to procure a credible VDA

A credible and professional VDA depends on the specialism and experience of the individual running the assessment and giving advice. A VDA provider must provide clients with several assurances that they are right for the job, which we have compiled in the following checklist:

  • Transparency: A VDA provider must be clear about what is being paid for as part of a VDA. This includes being transparent about what a client needs as part of their VDA to mitigate overspend. For example, unless a bespoke engineered solution is required, a client does not need to have kilojoule energy at the point of contact calculated.
  • Advice only: A VDA provider should be providing advice only. Their function is not to define scope, nor should they recommend specific products or providers. (One exception to this rule is when a bespoke solution is clearly required)
  • Rationalisation: A VDA provider will clearly explain why a client should consider HVM recommendations with evidence of strategic and critical thinking, i.e., looking at points of failure and not just points of success.
  • Referrals: Wherever possible choose a VDA provider who has been recommended to you and comes with ample references. Architects in particular along with CTSAs should look to include a trusted security consultant specialising in counter terror or errant vehicle HVM in their network.
  • Proof of execution: The scope of security is vast and therefore, the scope of a VDA can be similarly vast. To ensure that the right level of risk is mitigated, work only with professionals who can prove successful execution of VDAs on similar projects to your own.
  • Accountability: A VDA provider must have the right level of insurance and have their recommendations underwritten. They will be committed to upholding the golden thread and will readily stand behind their rationale in court if necessary.

VDAs and the ‘area of probability’

The core purpose of a VDA is to verify that products installed for hostile or errant vehicle mitigation are appropriate for the calculated speed of applicable vehicle sizes and weights, that can realistically encroach on specified locations.

On paper, that can sound somewhat formulaic but the reality of VDAs and subsequent recommendations is altogether more nuanced.

That’s because with security, especially in a HVM counter-terror scenario, almost anything is possible, but not everything is probable.

That area of ‘probability’ is where vulnerability lies. So, that is where decisions must focus. Fixed calculations may overlook game-changing context resulting in under or over specification.

For example, bollards capable of stopping a 7.5 tonne vehicle to a 5-metre penetration depth are recommended. But, there is only space for bollards three metres from the building lobby. On the other hand, HVM may be recommended to stop HGVs approaching at 50mph, despite natural obstructions on approach (such as narrow and windy streets) making the vehicle size and speed impossible.

A security professional will spot these nuances immediately.

In summary, a VDA is a balancing act between probability proportionality, and the stopping power of a specified product.

Specifiers and consultants: What value does a Vehicle Dynamic Assessment provide a client?

1) Certainty: From a client’s perspective, the greatest value of a VDA is the certainty if offers. As a result of calculated assessment and transparent, accountable (and ideally underwritten) advice, clients can unequivocally prove that their HVM solution is appropriate for the threat a site faces.

Simply put, clients can rest assured they have the best option to mitigate risk and can track every decision back to that crucial VDA.

2) Spend: A blanket ‘golden standard’ approach – when the highest specification product is chosen regardless of calculated threat – is rather common. However, it is not always justifiable.

That’s because to be justifiable and appropriate, HVM recommendations must be realistic, proportionate, sustainable and effective as per specific VDA findings. And that doesn’t always mean defending against 7.5 tonnes at 50mph if such a threat isn’t viable (i.e., a speed-limiting obstruction).

Sometimes, the best product option to mitigate risk may not exist. In these scenarios an engineered solution is required but up to that point, existing tested products will fit with VDA advice.

3) Liability: When a CTSA or security consultant delivers a VDA, those individuals are liable for the HVM advice provided.

ATG_VehicleDynamicAssessment2-23So long as a client acts on this advice, maintains regular inspections, doesn’t modify products and that manufacturers install products correctly, all legal liability rests at the door of the person who provided advice following a VDA.

In theory, if a VDA was scoped, run and interpreted as per best practice, there is no cause for concern. However, a crucial component of this is insurance. Independent Security Consultants are able to obtain insurance and underwrite the recommendations they make. CTSAs, though, are not, meaning that corporate manslaughter charges can be made.

Although the UK has yet to charge a CTSA or uninsured security consultant, that’s not to say prosecutions won’t happen. For example, while still being a draft bill, the Protect Duty is set to reframe liability in HVM situations. The best option for all parties is to place VDAs and advice into the hands of a counter terror specialist, dealing exclusively with HVM threats.

The importance of a VDA to the ‘golden thread’ principle

The golden thread is an accountability principle whereby a trail of every HVM decision is logged and accessible. The golden thread of security covers every stage of a project and every stakeholder involved, spanning from credible assessment (e.g. Threat assessments and VDAs), through to tested products procured, installed and maintained to manufacturer standards and operated as intended.

As the first stitch in the golden thread, a VDA is crucial to liability mitigation. In fact, if the worst was to happen, it will be the subject of immediate questioning: was a comprehensive VDA completed, who ran it and made recommendations, can it be produced?

A VDA demonstrates due diligence as part of the golden thread, and when completed by an insured expert, the chances of being convicted in court reduce enormously.

Summary: A VDA is always worth the money

VDAs deliver huge net benefits for what, in the grand scheme of a HVM project, amounts to very little cost. For a typical project, VDAs generally cost a few thousand pounds – negligible in comparison to expensive HVM solutions.

And in almost every scenario, money will be saved by undertaking a VDA. If engaging with the right security consultant, you fully understand risk and know whether HVM solutions are appropriate or excessive.

That means clients spend only the money they have to spend, crucially while maintaining an evidence trail that admonishes them of liability.

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