A key part in selecting the right Hostile Vehicle Mitigation measure is an understanding of how hard they might be hit. To understand this a Vehicle Dynamics Assessment (VDA) should be performed. The possible approach routes to each part of your target building or facility should be mapped, bearing in mind that normal ‘rules of the road’ become irrelevant for such a study. For each attack the length of run up distances, the radii of bends, inclines and declines and the nature of the surface need to be mapped out and recorded. Approved tables are then used for a logical selection of vehicle classes to establish the most probable velocity at impact (velocity being speed and direction). A VDA is a meticulous exercise and should be supported by a site visit or detailed photography and terrain and contour mapping where available.
It is also the case, that despite the comprehensive efforts so far, there will factors such as specific gradients that are not covered. In such cases it is possible to carry out practical tests with the perceived threat vehicle at the correct mass and see what speed is achievable.
It is important to remember that when undertaking a VDA, the normal rules of the road do not apply. Traffic lights, lane markings, correct side of the road, pedestrian zones, pavements and one way systems are to be ignored. Events have ably demonstrated that the driver of such a vehicle is not worried about his wellbeing or mid to long-term life expectancy. The driver is certainly not worried about preserving the paintwork on his vehicle or any other damage that will affect its future resale value.
From the appropriate scale mapping, each potential route is broken down into elements. Each element might allow the vehicle to accelerate along a straight section or have its speed limited by having to take a corner/make a bend. From a standing start, at the furthest point of the attack, the speed at the end of each element is used in the calculations for what happens in the next, and so on, until the target is hit. This impact may be straight on or it could be at angle, all important information with which to determine what rating any HVM equipment should be.
SJH Projects has undertaken many VDAs, both on the ground and as desktop exercises.
If you need help in determining what rating of HVM equipment you need to create a cohesive and effective perimeter to your location, then let us know.
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