What a proper HVM site survey covers before any product is chosen

The threat statement is the input every other decision depends on, and it needs to be specific to the site rather than copied from another project.

Start with the credible vehicle. What can actually be obtained, driven and brought to this location — and, just as importantly, what already comes here legitimately? A specification written around a 6,800 kg medium truck is indefensible on a site that receives thirty-tonne tankers daily, because the attack vehicle of choice is frequently one that is already expected at the gate.

Then set out the tactics being mitigated, because they demand different answers. A penetrative attack drives through the line at speed and is answered by rated barriers and by removing achievable speed. Encroachment at low speed into a crowd is answered by continuous lines and pedestrian protection rather than by high ratings. A parked vehicle-borne device is a standoff problem, not a barrier-strength problem, and is answered by keeping vehicles at a distance. Deception and layered attacks, where a vehicle follows an authorised one through a gate, are answered by interlocks and by the sequence at the entry point rather than by the barrier itself.

Write the threat statement down and have the client sign it. It is the document that justifies every cost in the scheme, and the one that protects the design when the budget is challenged.

A vehicle dynamics assessment models how a vehicle can actually behave on the approaches to your site: which routes are available, what speed is genuinely achievable at each point of impact, at what angle, and with what vehicle mass. The National Protective Security Authority treats it as the starting point for any hostile vehicle mitigation scheme, and publishes guidance for clients commissioning one, including the questions to put to a prospective provider.

It matters because both of the intuitive shortcuts are wrong. Assuming the posted speed limit understates what a determined driver can reach on a clear approach. Assuming maximum vehicle speed overstates it, because kerbs, radii, camber, level changes and the handling limits of a loaded truck all intervene — a heavy vehicle attempting a tight turn at speed may roll before it reaches the line at all.

The physics behind the result is worth keeping in view while reviewing it. Kinetic energy is half the mass times the square of the speed, so a 6,800 kg vehicle at 80 km/h arrives with roughly 1.7 megajoules, while the same vehicle at 48 km/h arrives with roughly 0.6 megajoules. Removing a third of the achievable speed removes well over half the energy. That is why road geometry, chicanes and approach treatment usually buy more protection per riyal than a higher barrier rating.

Underestimating the vehicle threat — the available vehicle types, their handling capability, or the approach speeds — is the failure mode that leaves a site exposed despite a fully compliant barrier line. Make the assessment a named deliverable rather than an assumption.

Most barrier products are constrained by what is under the ground, not by what is above it. Survey accordingly.

Establish the available depth along the whole intended line, not at one trial position. Buried services — power, communications, drainage, irrigation, fuel and process lines — must be traced on site with detection equipment and trial pits, because record drawings in the region are frequently out of date and a services corridor discovered during piling is a programme event. Record the water table, the ground bearing conditions and the presence of rock, since all three change what foundation is buildable.

Then record the geometry: levels and crossfall along the line, drainage routes and flood paths, the kerb line and footway widths, the turning circles that delivery vehicles need, and any existing structure that could serve as an anchor or an obstruction. Note overhead constraints and access for installation plant, because a bollard line that requires a crane in a live forecourt is an operational problem before it is a security one.

Finally, record where the line cannot be continuous. Every gate, crossing, ramp and drainage gap is a designed weakness that has to be closed by something else — an active barrier, a chicane, a guarded position — and each one has its own survey requirements.

A scheme that is secure and unusable will be defeated by the people who work there within a month, usually by leaving something open. So the survey has to capture normal operations in numbers.

Count the traffic: vehicles per hour at peak by type, the daily and weekly profile, and the seasonal peaks. Identify who must not be delayed — fire appliances and ambulances first, then shift buses, refuse, fuel, catering and the arrivals that carry reputational weight. Establish the inspection regime, because search and under-vehicle inspection consume time that has to be modelled against the arrival rate, and a queue that reaches the public road is both a traffic offence and a target.

Establish the staffing reality as well. A gate design that assumes two guards at all times will behave differently at 02:00 on a Friday with one. Ask what happens when an active barrier is out of service, and whether there is a defined manual procedure or whether the gate simply stays open.

Finally, look at emergency egress. Evacuation routes that cross the barrier line need a defined arrangement, agreed rather than improvised, and it should be tested during commissioning.

The distance between the barrier line and what you are protecting is usually the most valuable variable in the scheme, and the cheapest one to change early.

Record what sits behind the line: occupancy and where people gather, the facade and glazing type and whether it has been assessed, critical plant and single points of failure, fuel and chemical storage, and the routes emergency services would use. Then compare the standoff you have with the penetration band you intend to accept. A barrier certified with a penetration of up to seven metres, installed three metres from an occupied facade, has met its certificate and failed the design.

Where standoff is short and cannot be increased, say so in the survey and record it as a residual risk, with the options — a lower penetration band, a different barrier line position, facade treatment, or an operational control. That record is what allows a client to make an informed decision rather than discovering the constraint after handover.

A survey that produces a recommendation and no evidence is not a deliverable. Require a defined output set.

The signed threat statement, including credible vehicle types and masses and the tactics in scope. The vehicle dynamics assessment, with approach routes, achievable speeds and impact angles at each point on the line. A marked-up site drawing showing the protected line, every gap and how it is closed, standoff distances, and the buried services survey. Required barrier performance expressed as a full designation under one named standard and edition. Foundation constraints by location, including available depth and ground conditions. The operational requirements: traffic volumes, inspection regime, emergency access and failure procedures. And a residual risk register listing what has not been mitigated and why.

Two Saudi-specific threads should run through all of it. For petroleum, petrochemical, power, water, mining and similar facilities, the High Commission for Industrial Security is the regulator whose security directives apply and whose approval is a prerequisite for operation, so the survey should be aligned to that route from the start rather than reworked to suit it later. And anything that touches the public right of way — bollards on a footway, a gate that changes a road line, a queue that affects a junction — needs municipal and traffic authority engagement early, because those approvals sit on the critical path far more often than the equipment does.

Four failures recur often enough to be worth naming. Surveying the main gate only, and discovering the service yard later. Trusting record drawings for buried services instead of proving them on site. Specifying a rating before measuring standoff, so the penetration band is chosen after the budget is fixed. And surveying the site as it is today, rather than as it will be when the adjacent plot is developed and the quiet access road becomes a through route.

The fifth, and the most expensive, is treating the survey as a sales visit. A survey performed by the party who will supply the barrier, with no independent threat statement and no vehicle dynamics assessment, produces a scheme shaped by a catalogue. Keep the threat definition and the dynamics assessment separable from the supply, even where the same organisation ultimately delivers both.

Require the survey to deliver each of the following before any product is selected:

• A written threat statement, signed by the client, naming credible vehicle types and masses and the tactics in scope.
• A vehicle dynamics assessment covering approach routes, achievable impact speed and angle at each point on the line, by a competent provider.
• A buried services survey proven on site with detection equipment and trial pits, not from record drawings alone.
• Ground conditions, water table and available foundation depth recorded along the whole line, not at a single position.
• Levels, crossfall, drainage and flood routes, turning circles and installation plant access.
• Every gap in the line identified, with the measure that closes it.
• Standoff distance measured to each protected asset, and compared with the penetration band to be accepted.
• Traffic volumes at peak by vehicle type, the inspection regime, emergency access, and the procedure when a barrier is out of service.
• Required barrier performance expressed as a full designation under one named standard and edition.
• A residual risk register, listing what is not mitigated and the options considered.
• Regulatory route confirmed: HCIS engagement where the facility falls under its directives, and municipal or traffic authority approvals for anything in the public right of way.
• The threat statement and dynamics assessment procured so that they are not dependent on the barrier supplier.