Vehicle Arresting Device

The present invention relates to vehicle arresting devices, such as may be deployed by law enforcement agencies or military forces to safely stop the progress of a target vehicle for example if stolen or suspected to be engaged in criminal or hostile activity.

A known vehicle arresting device for these purposes is described in WO 2004/072382. It comprises a flexible substrate in the form of a net of generally rectangular planform intended to be laid flat on the ground across the path of an oncoming vehicle and having rows of upwardly-directed barbed spikes attached to the net along its leading edge (in the sense of its orientation to the oncoming vehicle). When a vehicle runs over the device the run-over spikes engage in its front tyres and the net is caused to wrap around the front wheels, the portion of the net between those wheels being pulled tight under the vehicle so that the tension in the net prevents further rotation of the wheels and the vehicle is brought to a stop. In practice this occurs in a similar distance to an emergency stop as if the vehicle's brakes had been applied, and has the advantage that it can stop the vehicle without causing serious damage to the vehicle or injury to its occupants.

Devices substantially in accordance with WO 2004/072382 are marketed by the present applicant under the registered trade mark "X-Net" and have been found to be safe and very effective in arresting target vehicles when properly deployed. In this respect it is usual for the device to be deployed manually across a road from a folded condition at one side of the road when used ad hoc at a location ahead of a target vehicle, or it can be similarly deployed by use of a motorised winch, e.g. as described in WO

2007/141479, when used at an established or temporary vehicle checkpoint. It is, however, important to making an arrest that the device is deployed in the correct angular orientation to the oncoming vehicle - namely flat on the ground with the spiked edge leading - and there may be circumstances under which it is desired to deploy a vehicle arresting device but where it cannot be guaranteed that the known device will unfold and settle in the correct orientation - for example if deployed from a moving vehicle ahead of the target vehicle or dropped from an aircraft into the path of the target vehicle or generally where it is desired to deploy a vehicle arresting device which can be effective irrespective of its particular angular orientation with respect to the direction of the oncoming vehicle.

With the foregoing in mind, in one aspect the present invention resides in a vehicle arresting device comprising a flexible substrate adapted to lie flat on the ground in the path of a vehicle to be arrested, with one or more rows of upwardly-directed spikes attached to the substrate around its outer periphery. In this way the device will be presented "spikes first" to the vehicle in whichever relative angular orientation it may be deployed.

The substrate of the device is preferably in the form of a net, or may be for example a panel of silk or other woven material, and may be of circular, polygonal or some other planform.

Preferably the device comprises means whereby it can open automatically from a folded or otherwise compacted condition so that the substrate lies flat on the ground with the spikes directed upwardly, which means may operate e.g. by use of an expanding gas and/or stored strain energy.

The invention also resides in a method of arresting a vehicle which comprises deploying a device as defined above on the ground in the path of the vehicle such that when the front tyres of the vehicle run over the outer periphery of the device one or more said spikes become embedded in each said tyre, the substrate becomes wrapped around the front wheels of the vehicle, and the portion thereof between those wheels is pulled tight under the vehicle, thereby preventing further rotation of those wheels.

The invention further resides in a method of deploying a device as defined above which comprises dropping or lowering the device to the ground from an aircraft or road vehicle at least initially in a folded or otherwise compacted condition, and causing the device to open so that the substrate lies flat on the ground with said spikes directed upwardly.

These and other aspects of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:-

Figure 1 is a plan view of one embodiment of a vehicle arresting device in accordance with the invention, in its deployed configuration;

Figure 2 is a plan view of the device of Figure 1 in a folded condition;

Figure 3 is a vertical section, to an enlarged scale, through a spike of the device of Figure 1 and its attachment to other components of the device;

Figure 4 illustrates two different relative angles of approach of a target vehicle to the device of Figure 1 ;

Figure 5 is a side view illustrating the deployment of devices according to the invention by air;

Figure 6 is a plan view of the devices as deployed in accordance with Figure 5;

Figure 7 is a plan view of another embodiment of a vehicle arresting device in accordance with the invention, in its deployed configuration; and

Figure 8 is a plan view of the device of Figure 7 in a folded condition.

With reference to Figure 1 there is shown a plan view of one embodiment of a vehicle arresting device 1 according to the invention in its deployed configuration, that is to say lying flat on the ground. The device comprises a net 2 of circular planform and with a central circular aperture 3, the actual mesh of the net only being depicted for a small portion 2A in the Figure. Edging strips of webbing material 4 and 5 are attached to the net 2 around its outer and inner peripheries respectively. Circumferential rows (rings) of upwardly-directed tyre-piercing spikes 6 - in this case three such rows - are also attached to the net 2 around substantially the whole of its outer periphery. The device is normally stored and transported in a folded condition as shown in Figure 2, radial fold lines - twelve in this case - being indicated at 7 in Figure 1.

The design of the spikes 6, and the method of their attachment to the net 2, may be similar to that for the device of WO 2004/072382 and is shown in Figure 3. Each spike 6 has a base portion 8 and a shaft portion 9 tipped with a sharply pointed, generally pyramidal barb 10, undercut at its base as indicated at 1OA. The spikes are held on the edging strip 4 at the desired spacing by multiple hook and loop contact fastener material such as that known under the registered trade mark "Velcro". Lengths of Velcro ^® hook material 11 are sewn to the edging strip 4 and the spikes 6 are attached in the required pattern by pads of Velcro ^® loop material 12 passing over the spike bases 8 and into contact with the surrounding hook material 11 , the pads 12 being apertured to pass the

barbs 10 and shafts 9 of the spikes. The spikes 6 are then attached to the net 2 by thrusting the barb 10 of each spike through a respective knot 2B of the net and passing the knot down to engage frictionally around its shaft 9. A plastics tube 13 is passed over the exposed length of each spike 6 to resist lifting of the net 2 along the shaft 9 and to prevent the barb 10 snagging on the net when it is folded for storage and transportation.

It will be appreciated that in its deployed condition the device 1 will be presented "spikes first" to any vehicle in whose path it lies, irrespective of the relative angular (rotational) orientation of the device to the vehicle path, for example as indicated for two relative angles of approach of target vehicles 14 in Figure 4. When a vehicle encounters the device its front tyres will each run over one or more adjacent spikes 6 in each row. As each spike 6 is encountered the surrounding tube 13 is crushed down by the tyre allowing the spike to penetrate the tyre, and its undercut 10A is designed to catch on the conventional steel braiding within a tyre carcass to resist removal. The net 2 therefore becomes attached to the front wheels of the vehicle at two locations around its outer periphery, being trapped between the bases 12 of the respective spikes 6 and the tyres in which the spikes are embedded. Continued movement of the vehicle therefore causes the net 2 to wrap around the front wheels and the portion between the wheels is pulled tight under the vehicle and around suspension components until its tension prevents further rotation of those wheels, thereby bringing the vehicle to a stop. In practice this occurs in a similar distance to an emergency stop as if the vehicle's brakes had been applied.

It is important to the successful operation of the device that the net 2 has sufficient stretch to absorb the loads that are imposed on it as it pulls tight to arrest a vehicle, and to allow the net to become fully wrapped around the front wheels before the tension builds up to a level at which there might otherwise be a risk of the spikes 6 being pulled from the tyres. This may be achieved for all relative approach angles with a single piece of netting 2 of uniform mesh and appropriate modulus. It is preferred, however, to adopt a mesh with loops of elongate form and with the longer dimension of the loops generally in the radial direction of the device in the initially deployed condition, for example the elongated diamond form of mesh oriented as shown for the net portion 2A in Figure 1. This is capable of significant elongation in the tangential direction of the device before the loops are pulled to a condition in which their longer dimension is in that direction and the net begins to tighten. The net 2 may be woven in a single piece with the desired initial generally radial mesh orientation around the whole net. Alternatively it may be

manufactured in the form of (in this case) twelve similar segments which are joined together along the fold lines 7, as by stitching, lacing or otherwise, to create the complete net 2.

It is of note that the presence of the edging strip 4 does not restrict the tangential elongation of the net 2 when arresting a vehicle because its attachment to the net is by means of the Velcro ^® pads 12 over the bases of the spikes 6 which can pull off from the Velcro ^® material 11 as the net stretches. For a similar reason it will be arranged that the attachment of the net 2 to the edging strip 5 at its inner periphery will be such as to permit release of the net for appropriate stretching in use of the device.

When operational conditions permit, the device 1 may be deployed manually in the path of a target vehicle. Turning to Figures 5 and 6, however, these depict an alternative form of deployment, by air.

In Figure 5 it is assumed that a target vehicle 15 has been identified on a roadway 16 and it is necessary to rapidly deploy one or more devices 1 in its path. A helicopter 17 carrying such devices is flown ahead of the vehicle 15 and drops in this case three devices 1 onto the roadway 16 in order to maximise the chances of a successful arrest. The devices 1 are dropped from the helicopter 17 in their folded condition and unfold on hitting the ground as indicated in Figure 6. Alternatively the unfolding process may start during the time taken to fall to the ground so that the device may be partially or fully unfolded by the time that it reaches the ground. For this purpose each device 1 may be equipped with a network of inflatable radial ribs and/or an inflatable rim which unfold the device when inflated e.g. by means of an associated compressed air bottle or pyrotechnic gas generator. A self-righting mechanism similar to those used on inflatable life rafts may also be employed to ensure that each device is deployed the right way up, i.e. with the spikes 6 pointing upwardly, and/or instead of free falling as indicated in Figure 5 the folded devices 1 may be equipped with parachutes or drogues to ensure that the corresponding package reaches the ground in a specified upright condition.

Alternatively if time permits the helicopter 17 may hover over a target area and lower the devices on a line, with or without ground personnel to assist in deployment. As an alternative to or in combination with an inflatable system the devices may employ stored strain energy for unfolding, e.g. from a network of ribs and/or rim of memory metal or other spring material. It is also possible that instead of folding as indicated in Figure 2 the devices may be folded like an umbrella and unfurled correspondingly.

Devices of this kind could likewise be deployed from the back of a moving road vehicle positioned ahead of the target vehicle.

Figures 7 and 8 illustrate another form of vehicle arresting device 1 ' according to the invention which is similar to the circular device 1 but instead is based upon a polygonal in this case octagonal - planform. It is in other respects constructionally and operationally similar to the device 1 of Figures 1 and 2 and corresponding parts are denoted by the same reference numerals with the addition of a prime (').