Hostile Vehicle Mitigation

Vehicle-borne threats range from vandalism to sophisticated or aggressive attack by determined criminals or terrorists. The mobility and payload capacity of a vehicle offers a convenient delivery mechanism for a large explosive device, although the vehicle itself may be used as a weapon. This section contains guidance that will help practitioners determine the vehicle-borne threat, assess site strengths and vulnerabilities, and identify suitable options for Hostile Vehicle Mitigation (HVM) measures.

Determining the type of vehicle-borne threat being faced

When specifying the nature of the vehicle-borne threat it is important to understand:

  • Modus Operandi (MO) - this includes parked, penetrative, encroachment, deception and duress or a combination of attack methods including surreptitious and forcible attack on the barrier with hand tools or explosives
  • Threat vehicle(s) - unmodified road vehicles with specific characteristics - mass, speed and structure, as well as vehicle specific capabilities
  • Blast effect - especially if considering VBIED attack
  • Stand-off distance from the asset/s - must be considered in conjunction with the site operational needs and security plan

How do I assess the strengths and vulnerabilities of my site to vehicle-borne threats?

Once the nature of threat is understood, practitioners should take a methodical and  considered approach to determine project objectives and highlight security vulnerabilities:

  • Develop detailed security requirements for HVM - Operational Requirements (OR) 
  • User Requirement Document (URD) if not covered in the detailed requirements - addressing additional business needs e.g. stakeholder liaison, planning and design
  • Practical site assessment - a layered approach incorporating the local area, blast stand-off, traffic management and vehicle access control
  • Technical assessment - e.g. Vehicle Dynamics Assessment (VDA) at specific locations based on the relevant threat vehicle(s)
  • Liaison with technical or security experts - e.g. CPNI or CTSAs, or RSES professionals with relevant experience

How can I reduce the vulnerability of my site and mitigate vehicle-borne threats?

Based on the project objectives and site assessment, a range of options can be incorporated into the design of a robust HVM strategy:

  • Principles of hostile vehicle mitigation - determine the aims of the HVM strategy and how it will integrate with other site security measures 
  • Traffic calming - can be used to limit vehicle approach speeds to a manageable level
  • Vehicle Security Barriers (VSB) -  provide proven vehicle impact protection and maintain blast stand-off.
  • Traffic management - when and how legitimate traffic will access the site
  • Vehicle access control - consider deployment of active VSB solutions, access procedures, long term operational management and emergency access 


What vehicle impact test standards should I be using?

CPNI recommend that a barrier deployed for the purposes of countering terrorism to protect assets against vehicle-borne threats should be a ‘Rated Vehicle Security Barrier’ that has undergone formal vehicle impact testing.

The testing should:

  • be conducted to a recognised vehicle impact test standard
  • be performed at an independent test house
  • achieve a performance rating in accordance with the chosen standard
  • Our guidance, Impact Testing of Vehicle Security Barriers, provides clarity and answers to recurring queries that circulate across the industry

For further information please see our advice note - Due diligence in the selection and procurement of vehicle security barriers.

Mitigating the risk to high streets

The risk to pedestrians from Vehicle As a Weapon (VAW) attack remains a real possibility during the COVID-19 pandemic. Social distancing measures will require authorities and businesses to guide customers in and around commercial premises and publicly accessible locations e.g. high streets. In order to minimise the risks to people, organisations and authorities can take practical steps to reduce the risk. CPNI has published guidance on protective security considerations for high street hospitality and guidance on protecting queues to counter this attack methodology.

Vulnerability of rising arm and swing arm barriers

Some rising arm and swing arm Vehicle Security Barriers (VSBs) are vulnerable to impact from smaller cars even though they may be able to stop a larger vehicles travelling at speed.

  CPNI recommends that rising & swing arm VSBs deployed to protect assets against vehicle borne threats should be tested and rated to the following standards and include an M1 classification vehicle i.e. passenger car:

In recent years, vehicle borne threats have evolved to include Vehicle as a Weapon (VAW) attacks, with perpetrators using a wide range of vehicles from passenger cars up to lorries. A number of security related incidents and terrorist attacks have involved or used hatchback and saloon cars to target people or attempt to breach perimeters. Their use remains a realistic possibility.  

Consequently, following a programme of research and full scale vehicle impact testing, CPNI recommends a full range of potential threat vehicles and attack methodologies (including a range of impact speeds) are considered when developing an HVM Operational RequirementAssurance should be sought during the tender procurement process that the proposed VSB attained the necessary vehicle impact performance rating/s against your identified vehicle borne threats.  

For rising arm and swing arm VSBs already in place, discuss your requirements with the original equipment manufacturer. HVM specialist members of the Register of Security Engineers and Specialists will also be able advise you of specific design features that may need addressing. 

Engineered design modifications to barriers should not be implemented without first validating the performance through vehicle impact testing as detailed above.

Additional advice may be sought from:

The six metre Cedar Gate successfully stops a car at 48 km/h (IWA14-1)

Public realm integration

Integration of HVM measures within the public realm is increasingly common and whilst requiring the application of informed design choices meeting the needs of numerous stakeholders, can provide proportionate security measures without impinging on the needs of local businesses or functionality of the public space.

In addition to the publication of a public realm design guide for hostile vehicle mitigation CPNI has collaborated with the Department for Transport to produce guidance regarding the incorporation of HVM measures in the public space and specific advice on the use of bollards and their effect on pedestrian movement.

The related documents and pages provide a range of advice on standards and selection of appropriate measures. External links are listed below:

ISO – IWA 14-1:2013 Vehicle security barriers – Part 1: Performance requirement, vehicle impact test method and performance rating
ISO – IWA 14-2:2013 Vehicle security barriers – Part 2: Application 
BSI – PAS 68:2013 Impact test specifications for vehicle security barrier systems 
BSI – PAS 69:2013 Guidance for the selection, installation and use of vehicle security barrier systems 
CEN - CWA 16221:2010 Vehicle security barriers. Performance requirements, test methods and guidance on application 

DFT-TAL 1/16: Influence of bollards on pedestrian evacuation
DfT-TAL 2/13: Bollards and pedestrian movement 
DfT TAL 1/11 Vehicle security barriers within the streetscape 
NaCTSO – Crowded places guidance 

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