Repelling terrorist attacks
Ports need to seriously consider implementing hostile vehicle mitigation measures, finds Barry Cross
Recent terrorist outrages using heavy goods vehicles as improvised weapons has generated concern among the general public, governments and law enforcement agencies. But ports, too, should be concerned as the sheer weight and size of these vehicles allows them to break through traditional perimeter security fences on many port-terminal boundaries.
There are mitigation solutions available to thwart hostile vehicle attacks, many of which start at the design level. The design of the perimeter and its components need to be considered as part of the overall security of a site, says Paul Gaston, one of the directors of DynaSystems. “Ultimately, an adversary will seek to exploit the weakest point to achieve their aim. Therefore, the elements [of a perimeter security solution] should seek to conceal their true strength,” he says, adding that a large part of this is managed through design and speed control.
Steve Bailes, a perimeter security expert at Zaun, notes that many maritime ports could potentially be at risk from hostile incursions by HGVs if they simply retain traditional palisade or chain-linked fences.
“Although we haven't yet had a port-related incident in the UK involving an HGV being used as a weapon this doesn't mean that this could not be a future threat,” he says. Protecting airport terminals from similar incursions underwent a sea change in 2007 when a jeep was used to smash its way into the terminal building at Glasgow, which was full of passengers.
Given the location of some port terminals close to perimeter roads, fences erected to keep intruders from entering a premises will do little to repel a hostile vehicle. And once within a terminal, the potential havoc such a vehicle could cause is enormous.
“There are lots of things that you can do to mitigate such incidents. The main danger comes from an HGV being driven head on into the fence. By realigning roadways, which can involve putting in chicanes where appropriate that becomes much more difficult,” says Mr Bailes. “You can also put bollards in place, making certain sections of fencing a lot less attractive for terrorist strikes.”
Upgrading existing installations can be done relatively quickly and within tight budgets. Zaun, for example, will take a look at a potential customer's premises and identify vulnerable points, where simple redesigns or upgraded fences would mitigate hostile intrusion from road vehicles.
“Modern fencing can be designed to completely stop a certain size of HGV ramming it at a given speed. In most cases, this will result in the virtual decapitation of the vehicle at the perimeter. However, in many ports, a head on strike is less likely, which means that a hostile vehicle, even if it is very large, will bounce off a well-built fence all together,” says Mr Bailes.
A lot of fences nowadays, he adds, don't require deep foundations to perform effectively, although certain key structures may require footings of up to one metre of concrete. This helps make swapping old fences for new ones highly cost effective.
“At Zaun, we offer a range of products that could help boost a port terminal's perimeter; and where we don't produce an exact solution ourselves, we work with external partners to ensure that we can upgrade any existing facilities to make them safer,” says Mr Bailes.
At Dynasystems, the company's main solution is the Universal Construction System (DUCS), which is, essentially, a blast mitigation system whose key features are claimed to be its modularity and ease of transport.
It is one of a range of products which, although developed for the military, are now used to protect a variety of critical national infrastructure installations around the world. In Iraq and Afghanistan, DUCS was used to ensure that both walls and towers could be erected quickly to protect installations.
According to Mr Gaston, ports that believe that existing perimeter fences leave them vulnerable could benefit from deploying DUCS. “Systems can be delivered onto site as a flat pack, then constructed by local labour. Being flexible, the structures can be moved around and later dismantled,” he notes.
The concrete-filled cubes, which are clad in Dynablok panels that add ductility to the concrete, can withstand a major blast, since the concrete flexes rather than shatters. The composite material properties allow the wall to increase its energy absorbent capability by allowing it to deform without spall up to a rotation angle of eight degrees, nearly twice that of a regular reinforced concrete wall. The cubes can also be stacked on top of one another to form a tower.
In this configuration, they are held together by specially developed energy absorbing spring bolts. Should a tower be subjected to a blast, it will sway slightly, but not fall over. The connections mitigate the effects of ground shock being transmitted through the floor, thereby protecting the occupant's limbs from injury.
“Dynasystems products have been subjected to extensive testing by a variety of international government testing and evaluation agencies,” says Mr Gaston. “Furthermore, our products have been installed in a number of high profile military and civil locations in some of the world's most hostile environments.”
Another of the company's solutions is the Dynablok wall system, which has been designed to use Dynablok panels as the formwork for concrete pouring, thus eliminating the need for complex formwork assembly and disassembly. Furthermore, the panels are designed with an interlocking mechanism and connectors, which enable speed and ease of construction.
“Because of its use of recycled materials - which provide excellent thermal and acoustic insulation as well as being fire-resistant - the Dynablok walling system is recognised as being “green” building technology, too,” says Mr Gaston.
Significantly, Dynablok panels are lightweight and easy to handle, resulting in nearly 30% reduced total wall weight compared to a typical concrete wall. This, adds Mr Gaston, allows for better protection with less mass, which in turn results in smaller support footprints, something that is key in space-constrained port terminals.
The units are invariably in use in high risk locations such as entry control points where potential threats from vehicle borne attacks need to be mitigated. Because of their modular design they can be moved to reflect changes in layout due to expansion or other operational reasons which makes them an economic and flexible solution.
BARRIER SYSTEMS DISSIPATE ENERGY
J&S Franklin has developed a range of both non-metallic and metallic barrier systems that are marketed under the “Defencell” brand. These, claims sales manager Jeremy Milton, could be used by ports and port terminals to mitigate possible incursions by HGVs, preventing them from reaching key areas and causing substantial damage.
According to Mr Milton, the main product of interest to the ports sector is the “Profile”, which consists of a series of polypropylene geo-textile containers that can be filled with locally available recyclable materials, such as sand, earth or crushed rock. Each unit is porous, so any water ingress is naturally drained away.
The containers can be stacked so that each overlaps the next to form a protective barrier, which is sufficient to easily stop an 18.5-ton truck striking it at 40mph.
“Each container has an inner cellular structure, which dissipates energy along the barrier rather than at the point of impact. This compares to a standard concrete barrier, which, when struck, would simply be forced backwards,” says Milton.
The containers can also be stacked to form a berm, which is mound that can be turned into a discrete structure when covered with either grass or foliage. Given the material used, the berm could potentially remain in place for 20-30 years. The berm is structured to have a 50-degree facing edge, effectively preventing any vehicle from climbing over it, thereby given added protection in areas of the port that are vulnerable to ingress from vehicles running at speed along perimeter roads.
Alternatively, says Milton, profile units can be stacked to provide a temporary barrier, if, for example, work needed to be undertaken on a perimeter fence, potentially leaving a vulnerable gap for several days. The containers could be stationed inside the work area for as long as necessary.
“Profile units also send out a message to potential terrorists that a terminal is serious about preventing incursions,” says Mr Milton.
“It's an economical system, requiring little maintenance and is long lasting, as well as being discrete. Furthermore, it offers a good level of blast protection, being able to mitigate the effect of a standard car or truck bomb.”
Little skill is required in the installation and it is possible to put in place 30-50 metres of protective barrier in a day, using standard diggers and compacting tools. Being surface mounted, there is no need to move underground installations either.
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