Security Barrier
This invention relates to security barriers and, in particular but not exclusively,
to barriers that provide an effective perimeter protection against wilful intrusion into
high security installations such as airports.
A known anti-vehicle barrier is described in the Applicant's co-pending patent
application number GB2447783. This document discloses a perimeter security barrier
for restraining a vehicle impacting the barrier from a direction substantially
perpendicular thereto or between 25 and 90 degrees relative to the barrier. The barrier
comprises a plurality of wire ropes supported by a series of posts configured to restrain
heavy impacting vehicles.
High security installations such as airports, defence installations etc are,
however, not only prone to attacks by vehicles but also by pedestrians wishing to gain
access thereto. The anti-vehicle fence discussed above would be ineffective against
intrusion by persons who could simply climb over or through the wire ropes. Specialist
anti-personnel fences, comprising panels of small mesh spacing, are known in the art
that are resistant to cutting and climb-over.
The present invention has been devised with the problem of how to effectively
protect against breaches by both persons and vehicles.
According to the present invention, there is provided a security barrier
comprising a first fence and a second fence, the first fence comprising a first series of
posts and the second fence comprising a second series of posts, the first and second
fences being provided adjacent to each other with the first fence being coupled below
ground level with the second fence, wherein the barrier further comprises a footing
having a first post socket for receiving a first post from the first fence and a second post
socket for receiving a first post from the second fence.
It is an advantage that two separate fences are used for the purpose of
preventing access by both vehicles and persons since this avoids providing a single
dual-purpose barrier that is more complex to manufacture and expensive to repair in
the event of a vehicle impact or other damage. However, coupling the fences together
underground provides the further advantage of strengthening the foundations of the
barrier and therefore the barrier itself. It is a further advantage in providing sockets for
each fence post as, in the event of damage to one of the fences, such as by a vehicle
impact, the sockets allow easier and quicker repair of the damaged fence post and
therefore the barrier. Furthermore, by providing both sockets in the same footing, the
strength of the barrier footing is increased relative to providing separate footings for
each socket. Manufacture of the footing for the barrier is also easier with a single
footing.
In an embodiment, the coupling between the first and second fences is provided
between the first post socket and the second post socket. By coupling the fences in
this way, the energy from any impact with one of the fences is at least partially
insulated from the second fence. This is advantageous as it minimises the area of the
barrier damaged thus minimising the area of any breach in the fence that may require
guarding.
Preferably, the footing is formed of concrete. The first and second post sockets
may be of different dimensions. Alternatively, the sockets may be of the same
dimensions.
One or both post sockets may comprise separate inserts - e.g. a liner,
preferably of metal - provided within correspondingly sized apertures within the footing.
This enables easy replacement of the sockets and/or posts in the event of damage due
to an impact. Alternatively, the posts may be fixed directly within the footing etc.
The common footing provided for posts of the first and second fences provides
a secure foundation and adds strength to the barrier, which may be subjected to a high
energy impact from an oncoming vehicle. The common footing also helps to dissipate
energy from the impact through the posts to the footing and ground thus assists in
arresting the vehicle.
In an embodiment, the barrier further comprises connecting means for
connecting the first post of the first fence to the first post of the second fence below
ground level. The connecting means may comprise one or more bolts connecting the
first and second posts and/or sockets. This further strengthens the foundation and aids
energy dissipation in the event of an impact by a vehicle.
In an embodiment the first and second sockets are separated by a spacing
means. Preferably, the posts are separated by a distance of between 2 and 20cm.
Preferably the separation is less than 10cm. Desirably, the first and second sockets
are separated by a distance of 5.0 or 5.5cm. The two fences are preferably provided
as close together as possible, just leaving space therebetween to allow maintenance
access - e.g. for rope tensioning or replacement/re-hanging of ropes following an
impact.
Mounting the two fences close together advantageously reduces the footprint
required on the land. It furthermore facilitates maintenance of the surrounding land
and/or environment as maximum access is provided to the land near the barrier without
the need to interfere with the barrier itself (which may be dangerous due to the threat of
attack of the installation). Furthermore, if the two fences were separated further with a
'no-man's land' therebetween, it would be visually more obtrusive.
In a preferred embodiment the barrier comprises a plurality of footings, each for
coupling a first fence with a second fence such that the first and second fences extend
substantially in the same direction as one another.
The first fence may be an anti-personnel fence configured to prevent access
from pedestrian intruders and the second fence may be a vehicle mitigating fence
configured to withstand and absorb energy from an impact by a vehicle. Preferably,
the anti-personnel fence is disposed with respect to the vehicle mitigating fence such
that the anti-personnel fence will be impacted first by an oncoming vehicle. The vehicle
mitigating fence is thus provided on the opposite side of the barrier (i.e. the side
immediately adjacent the area to be protected). This arrangement helps to minimise
the damage to the barrier as collapse of the anti-personnel fence into the vehicle
mitigating fence has less of an effect on the vehicle mitigating fence than if the vehicle
mitigating fence was disposed on the impact side of the barrier with the antipersonnel
fence being provided on the installation side thereof.
Mounting the two fences close together advantageously controls damage to the
antipersonnel fence since, in the event of a vehicle impact, the vehicle engages with
the anti-personnel fence first and then with the vehicle mitigating fence shortly
thereafter. The closeness of the fences and the effectiveness of the vehicle mitigating
fence in arresting the vehicle means that minimal damage to the anti-personnel fence
occurs. If the anti-personnel fence were provided at a greater distance from the vehicle
mitigating fence, it would be more susceptible to damage over a greater length since it
is inherently not as strong or resistant to damage as the vehicle mitigating fence. If the
two fences were separated at a distance approximately equal to or less than the height
of the anti-personnel fence, a vehicle impacting the anti-personnel fence could force it
down onto the vehicle mitigating fence such that the former acts as a ramp for a vehicle
to breach the latter.
Alternatively, the vehicle mitigating fence is disposed on the impact side of the
barrier with the antipersonnel fence being provided on the installation side thereof.
In an embodiment, the vehicle mitigating fence comprises a plurality of wire
ropes supported by the second series of posts, and the anti-personnel fence comprises
a series of meshed panels supported on the first series of posts. This advantageously
allows a clear line of sight through the fence, enabling visual security checks to be
performed. The vehicle mitigating fence may comprise one or more ropes woven with
respect to the posts and/or one or more unwoven ropes disposed on one side of the
series of posts.
One or each end of the plurality of ropes of the vehicle mitigating fence may
terminate in a terminal, preferably a terminal provided on or in the ground. The last
post in the series of posts of the vehicle mitigating fence may comprise means on or
within the post for supporting the ropes. It is preferable for the ropes to enter the
terminal from the end post at an angle that enables the separation of the vehicle
mitigating fence and the anti-personnel fence to remain substantially constant. That is
to say, even though a terminal for receiving the ends of the ropes of the vehicle
mitigating fence is provided, this does not alter the line of the anti-vehicle or ant i
personnel fence and no interruption or deviation thereof is required.
It is a further advantage that, in the event of an impact to the combined barrier,
the damage to the anti-personnel fence is localised such as to only affect a single or a
small number of panels. Panels away from the vicinity of the impact remain intact or at
least in a condition to withstand further impacts. The vehicle mitigating fence also
remains in place with only a small number of posts in the area local to the impact itself
being bent/deformed. The combined fence thus remains operable allowing time for
repairs to be made thereto whilst still providing a good degree of security.
In another aspect, a post footing for use with a security barrier is provided, as
described above.
Figure 1 shows a perspective view of a security barrier according to an
embodiment of the invention;
Figures 2a to 2c show front elevational views of sections of the security barrier
according to an embodiment of the invention;
Figures 3a and 3b are end views of the security barrier of Figures 2a to 2c;
Figure 4a is a top plan view of an end post and terminal according to an
embodiment of the invention;
Figure 4b is a top plan view of an end post and terminal according to another
embodiment of the invention;
Figure 4c is a top plan view of an end post and terminal according to a further
embodiment of the invention;
Figure 5a is a front perspective view of the end post of the embodiment of
Figure 4a;
Figure 5b is a rear perspective view of an end post;
Figures 6 to 8 show the security barrier of Figure 1 before and after an impact
by a vehicle.
Figure 1 shows a security barrier 10. The barrier 10 comprises a vehicle
mitigating fence 20 for protecting an installation (not shown) against otherwise
penetrative vehicular attacks. The barrier 10 further comprises an anti-personnel fence
40 designed to keep pedestrian intruders out of the installation.
The anti-vehicle fence 20, e.g. Bristorm® manufactured by Hill & Smith Limited,
is intended to restrain heavy vehicles impacting from a direction that is substantially
perpendicular, or at an angle of between 25 and 90 degrees, to the line of the barrier.
Breach of the barrier by a heavy goods vehicle in the order of 7500 kg inertial mass
impacting the barrier at speeds of about 64-80 km/hr is prevented.
The vehicle mitigating fence 20 comprises a series of posts 22 mounted in the
ground. A plurality of ropes 24 are supported on the posts 22. The ropes 24 may be
plastic coated, high tensile steel ropes or cables that are pre-tensioned between the
posts 22.
The ropes 24 may be disposed at a height of between 300 mm and 2 metres
above the ground. The height position of at least some of the ropes 24 is selected to
be such that the engine of an impacting vehicle will impact them. Ropes 24 may be
provided at varying heights above the ground, for absorbing energy from a range of
vehicles of varying sizes.
In the embodiment of Figures 1, 2a-c, 3a and 5a-8, a pair of wire ropes 24a,
24b is provided at or approximately at the midpoint of the posts 22 (i.e. approximately
halfway from the ground level to the top of the posts 22). The ropes 24a, 24b are
sinuously woven with respect to the posts such that a first rope 24a of the pair passes
on a first side of a first post 22, and on an opposite, second side of an adjacent post
22, and so on. The second rope 24b of the pair passes on a corresponding second
side of the first post 22, and on a first side of the adjacent post, etc. An additional rope
24c is sinuously woven between the posts 22 at a vertical position lower than the rope
pair 24a, 24b, and a further rope 24d is sinuously woven between the posts 22 at a
vertical position higher than the rope pair 24a, 24b. These additional ropes 24c, 24d
are oppositely woven with respect to each other such that one passes on a first side of
one post and the other passes on the opposite, second side thereof. A further rope
24e is provided within a slot 26 in the top of the posts 22. Other configurations are
envisaged, e.g. a different combination of woven and unwoven ropes, or with further
woven rope pairs or additional woven or unwoven ropes.
As shown in Figures 1, 3a and 5b, the ropes 24 are supported on the posts 22
using one or more hooks 28 e.g. formed/angled from a stainless steel bar and fixed
within corresponding apertures provided within the posts 22 e.g. with bolts. The design
parameters of the barrier are such that, on impact, the intermediate posts are pushed
back to incline away from the impact direction by up to 40 degrees. The angle of the
hook 28 is such that the ropes 24 will tend to separate from the hook 28 when the
posts 22 are pushed back during impact.
The intermediate posts may be inclined relative to the vertical towards the
predetermined direction, that is, towards the oncoming vehicle. The inclination of the
intermediate post(s) to the vertical may be between 0 and 45 degrees, preferably
between 0 and 20 degrees, and more preferably 10 degrees.
The barrier 10 may be provided as a perimeter security barrier - i.e. extending
around and enclosing an installation, or a length thereof may be provided to e.g. span
the distance between two buildings, walls or other solid structures.
Referring to Figures 4a-c and 5a-b, at an end of the vehicle mitigating fence 20,
the ropes 24 pass around, or are supported by an end post 30. The end post 30 is
vertical and anchored in the ground. A rope support device is provided on the end post
30. In the embodiment of Figure 5b, the rope support device is a tab 3 1 welded or
integrally formed with the post 30. One or more apertures 31a are provided within the
tab 3 1 for receiving one or more ropes 24. In the embodiment shown in Figure 5b,
each of the five ropes 24 pass through and are thus supported by a separate tab
aperture 31a. In alternative embodiments (not shown), the ropes may be supported by
other means e.g. apertures or grooves/notches provided directly within the post 30, or
hooks or provided on the post 30.
The ropes 24 are anchored at each end thereof and terminate in a rope terminal
32. In the embodiments of Figures 4a, 4b, 4c and 5a, the terminal 32 is provided on or
in the ground. The ground terminal 32 may be in the form of bolts or another suitable
mechanical rope gripping device. The terminal 32 also holds the ropes in tension. The
ropes may be tensioned after hanging on the posts 22, and the terminal 32 then acts to
maintain the tension therein. A load or energy-absorbing device (not shown) may be
provided between respective ends of the ropes 24 and the posts 30/terminal 32. This
device may be in the form of a hot rolled channel section or hollow tube that is
configured to absorb energy transmitted from the impacting vehicle by the ropes. The
energy-absorption means is designed to deform under the increased tension load in
the ropes during impact by a vehicle. This limits the peak rope loads to tolerable levels
and restrains the ropes in order that they develop tension to resist penetration or
breach of the barrier by the impacting vehicle.
In the embodiment shown in Figure 4a, the ropes pass around the end post 30
and are fed into the terminal 32 at an angle that is, generally speaking, approximately
equal to or slightly greater than 90° relative to the initial direction of the fences 20, 40.
The ropes 24 pass through tab apertures 31a as described above. Figure 4a shows an
example of termination of the vehicle mitigating fence 20 earlier than the anti-personnel
fence 40.
Figure 4b shows an alternative embodiment wherein two runs of vehiclemitigating
fence 20, 20' are terminated using a common end post 30. The ropes 24 of
a first vehicle mitigating fence 20 pass around the end post 30 as described above and
terminate in a terminal 32. The ropes 24' of a second vehicle mitigating fence 20' pass
around the end post 30 as described above and terminate in a second terminal 32'.
The ropes 24, 24' pass through tab apertures 31a as described above. Separate or
common apertures 31a may be provided for the ropes of each of the two fences 20,
20'.
In each of the embodiments of Figures 4a and 4b, the terminals 32 are inset
from the line of the barrier 10 a little such that the ropes 24 of the vehicle mitigating
fence 20, 20' enter the terminals 32, 32' at an angle slightly greater than 90° relative to
the original direction of the fence 20. This enables the vehicle mitigating fence 20, 20'
and the anti-personnel fence 40 to be situated close together, at substantially the same
separation along the length of the barrier 10 (apart from in the vicinity of where the
ropes 24 pass around the end post 30 - as can be seen in Figures 4a, 4b). In the
embodiments of Figures 4a and 4b, this enables the barrier 10 to be provided with a
90° change of direction. If the terminals 32, 32' were provided at 90° to the original line
of the vehicle mitigating fence 20, this would necessitate a change in the line of the
anti-personnel fence 20 e.g. by flaring it out around the terminals 32. Similarly, in some
known wire rope barriers used for other purposes, the ropes thereof terminate in the
end post itself (i.e. a ground terminal is not used) which, if incorporated in
embodiments of the present invention, would also require flaring out of an adjacent
anti-personnel fence.
It will also be appreciated that the terminals 32, 32' could be provided at
different locations in order to provide a different change of angle (i.e. other than 90°) at
which lengths of vehicle mitigating fence 20, 20' are provided. Posts similar to the end
posts 30 shown in Figures 4a and 5a could also be utilised in directing the ropes 24 of
a single fence 20 to continue at a different angle - 90° or otherwise - e.g. as would be
required if the barrier 10 is employed as a perimeter barrier.
Figure 4c shows an alternative embodiment wherein termination of two runs of
vehicle mitigating fence 20, 20' is required without any change of angle. Again, the
ropes 24, 24' pass through tab apertures 31a on the post 30 and exit at an angle to
terminate in respective terminals 32, 32' such that the vehicle mitigating fences 20, 20'
are provided substantially in line with each other with no change of angle
therebetween. This enables the vehicle mitigating fence 20, 20' to run substantially in
a straight line parallel to the anti-personnel fence 40.
The fences 20, 40 are thus arranged to extend substantially in the same
direction as one another and, when a change in direction is required they remain close
together and continue to extend in substantially the same direction after the change in
angle. The fences 20, 40 may run in a straight line, approximately parallel to one
another, at least over a length thereof. Depending on the nature of the installation to
be protected, the fences 20, 40 may be required to change direction at certain locations
along the length thereof. The ropes 24 can be anchored at any angle relative to the
original direction of a length of fence 20, or in line therewith, depending on the site
topography and/or installation requirements. The fences 20, 40 may also be
terminated in different locations. This provides flexibility to protect a variety of areas of
land/installations.
The anti-personnel fence 40, e.g. Secureguard™ provided by Barkers Fencing,
provides protection against wilful intrusion by people and is designed to mitigate
against intruders climbing over and cutting through the fence. A series of posts 42 are
mounted in the ground. A plurality of mesh panels 44 are secured to the posts 42 e.g.
with tamper-proof bolts 45 (shown in Figure 3b). Alternatively, the anti-personnel fence
may be of the chain link or palisade type. The mesh size is small (e.g. 75mm x
12.5mm produced with 4.00mm +/- 0.10mm wire). The posts 42 are taller than those
22 of the anti-vehicle fence 20, e.g. by approximately a factor of 2, such that the antipersonnel
fence 40 extends vertically beyond the vehicle mitigating fence 20. The ant i
personnel fence 40 is required to be tall in order to keep intruders out of the installation.
The anti-personnel fence can be provided with or without strainer posts 46 e.g. as
shown in Figures 4b, 4c. In an embodiment, strainer posts are used at corners and
intermediate posts of the anti-personnel fence 40 where tensioned line wires are used
to support the mesh (not shown). The strainer post has a "leg" bolted to the side of the
post at an angle of about 45 degrees.
The vehicle mitigating fence 20 and the anti-personnel fence 40 are mounted in
the ground in close proximity to one another. Typically, the minimum spacing required
therebetween is determined by the diameter of the rope 24 plus space to allow access
for installing/rehanging ropes etc. A typical rope diameter used is 15.7mm (excluding
the plastic coating that is preferably provided on the rope). Based on this, plus a small
margin for tolerances plus allowing space for fitting/maintenance access, the gap
between adjacent faces on the posts 22, 42 may be within approximately 2-1 5cm, and
preferably substantially at a separation of 5.5cm. Larger spacings e.g. 20cm or more
are envisaged, but this would compromise the benefit of the barrier 10 occupying only
a small footprint on the land. This spacing allows for the fitting or removal of one of the
ropes 24 without the need to dismantle the entire fence 20. This is particularly
important when repairing the barrier 10 following an impact.
Referring again to Figures 3a and 3b, the vehicle mitigating fence 20 and the
anti-personnel fence 40 are mounted in the ground in a common footing or foundation
50. The footing 50 is provided entirely within the ground. A first channel 52 is sized to
receive the lower end of post 22 of the anti-vehicle fence 20. A second channel 54 is
sized to receive the lower end of post 42 of the anti-intruder fence 40. In the
embodiment shown, the channel 52 for the vehicle mitigating barrier post 22 is wider
and shallower than the channel 54 for the anti-personnel barrier post 42. It will,
however, be appreciated that each channel 52, 54 may be of any width, depth and
height to accommodate different sized posts 22, 42.
Figure 3b shows the footing 50 and details of how the ends of the posts 22, 42
are provided therein. A socket 53a is provided within the channel 52, the end of the
post 22 being received therein. A similar socket 53b is provided within the channel 54
with the end of post 42 being received therein. Each socket 53a, 53b is a metal insert
or sleeve corresponding in size externally to the internal dimensions of the channels
52, 54. The internal size of the socket 53a, 53b correspond to the external dimensions
of the end of the posts 22, 42. The depth of the sockets 53a, 53b define the height of
the posts 22, 42 of the vehicle-mitigating fence 20 and the anti-personnel fence 40
above ground and can vary from post to post and for different installations.
One or more spacer blocks 55 are provided within the footing 50 between the
socket 53a for the vehicle-mitigating fence post 22 and the socket 53b for the anti
personnel fence post 42. In the embodiment shown, two spacer blocks 55 are
provided, welded or otherwise secured to the anti-vehicle post socket 53a. The spacer
blocks 55 can be of any size chosen to define the desired spacing between the posts
22, 42 - e.g. 5.5cm in width as discussed above. The socket 53b for the ant i
personnel fence post 42 is provided with one or more apertures (corresponding to the
number of spacer blocks 55 being used) through which a bolt 57 is provided. The bolt
57 couples the socket 53b of the anti-personnel fence post 42 to the socket 53a and
thus to the vehicle-mitigating fence post 22. Additionally, the anti-personnel fence post
42 is provided with one or more apertures corresponding to the apertures in the socket
53b. The bolt 57 can therefore pass through the apertures of the anti-personnel fence
post 42 to couple the socket 53b and the anti-personnel fence post 42. The position of
the apertures in the socket 53b, anti-personnel posts 42 and thus the position of the
spacer blocks 55 can be chosen relative to the socket 53a for the post 22 of the
vehicle-mitigating fence 20 to control the height of the anti-personnel fence 40 above
the ground. It will be appreciated that the post 42 of the anti-personnel fence 40 could
be provided in a sleeve (not shown) such that one or both posts 22, 42 are mounted in
a sleeve in the footing 50. The spacer block 55 could be welded or bolted (for
example) to either or both sleeves.
A footplate 56 may be provided on the base of one or each of the posts 22, 42.
The footplate 56 helps to secure the post 22, 42 in the footing 50, especially since the
post 22, 42 may be subject to a high-energy impact from a colliding vehicle.
The two fences 20, 40 are thus coupled together underground via the coupling
between the sockets 53a, 53b but remain independent of each other above ground
level. Preferably, the footing 50 is a concrete footing such that the ends of the posts
22, 42 are embedded within the concrete.
In order to erect the barrier 10, the coupled sockets 53a, 53b and anti
personnel fence post 42 are positioned and suspended within a hole in the ground at
the desired height within the hole (defined by the predetermined height of the sockets
53a, 53b). Concrete is then poured into the hole in order to secure the sockets 53a,
53b and post 42 therein. The mesh panels 44 are then attached to the posts 42 of the
anti-personnel fence, and the ropes 24 are mounted on the posts 22 of the vehiclemitigating
fence 20, terminating at the end posts 30 and terminals 32.
As can be seen in Figures 2, 4a, 4b and 4c a larger common footing 60 is
provided in which an end post 30 and one or more adjacent fence posts 22, 22', 42 are
mounted. The common footing 60, preferably concrete, can be of any size to
accommodate the required number of posts 22, 22', 42, 60. The ground terminals 32,
32' can also be mounted on/within the footing 60.
Figure 6 shows a security fence 10 according to embodiments of the invention
just prior to a collision by an oncoming vehicle. The fence 10 is constructed so that an
impacting vehicle will first make contact with the anti-personnel fence 40, and then with
the vehicle mitigating fence 20. As discussed above, the majority of the ropes 24 of the
vehicle mitigating fence 20 are provided at a height that corresponds to the front /
bumper of the vehicle. An impacting vehicle makes contact with the ropes 24 which
push back on the posts 22. This transmits energy to the posts 22 adjacent to the
impact zone, thereby spreading the impact load along the length of the fence 20.
Impact energy is also dissipated through the posts into the common footing 50 and into
the ground.
Figures 7 and 8 show the security barrier 10 after an impact has occurred. It
can be seen that the posts 22 of the vehicle mitigating fence 20 in the vicinity of the
impact have been bent or deformed, but are still standing with at least some of the
ropes 24 being maintained in position with respect to the posts 22. Away from the
impact zone, the posts 22 remain upright with the ropes 24 substantially in their original
positions. Although damaged, the anti-vehicle fence 20 is still capable of withstanding
further impacts from vehicles along its length, and especially away from the point of
impact.
Directly in the vicinity of the impact the panels 44 of the anti-personnel fence 40
have been damaged. The construction of the fence 40, whereby mesh panels 44 are
bolted to the posts 42, means that in the event of an impact the panels 44 in the impact
area are stripped from the posts 42, shown clearly in Figure 8. Since the fence 40
more easily succumbs to damage under impact, the degree of damage away from the
point of impact is less such that only one, two or three panels 44 and posts 42 may be
damaged. The remainder of the fence 40 remains substantially undamaged.
It is therefore easy and inexpensive to replace damaged panels 44 and posts
42, 22 in order to return the security barrier 10 to full containment.
Embodiments of the invention employ separate anti-personnel and anti-vehicle
fences, independent above ground, which advantageously provide great flexibility in
that the design can be adapted to match an existing perimeter or to provide whatever
level of perimeter protection is desired.
A security barrier comprising a first fence and a second fence, the first fence
comprising a first series of posts and the second fence comprising a second
series of posts, the first and second fences being provided adjacent to each
other with the first fence being coupled below ground level with the second
fence;
wherein the barrier further comprises a footing having a first post socket for
receiving a first post from the first fence and a second post socket for
receiving a first post from the second fence.
The barrier of claim 1, wherein the coupling between the first and second
fences is provided between the first post socket and the second post
socket.
The barrier of claim 1 or claim 2, wherein said footing is formed of concrete.
The barrier of any preceding claim, wherein the first post socket and/or the
second post socket is a liner provided within the footing.
The barrier of any preceding claim, wherein the first and second post
sockets are of different dimensions.
The barrier of any preceding claim, further comprising connecting means for
connecting the first post of the first fence with the first post of the second
fence within said footing.
The barrier of claim 6, wherein the connecting means comprise one or more
bolts connecting the first and second posts.
The barrier of any preceding claim, further comprising a spacing means for
separating the first post socket from the second post socket within the
footing.
The barrier of any preceding claim, wherein the first posts of said first and
second fences are separated by a distance of between 2 and 10cm.
The barrier of any preceding claim, wherein the first posts of said first and
second fences are separated by a distance of 5.5cm.
The barrier of any preceding claim, comprising a plurality of footings, each
for coupling the first fence with the second fence such that, over at least a
portion of the barrier, the first and second fences extend substantially in the
same direction as one another.
12. The barrier of claim 11 wherein the first fence is an anti-personnel fence
configured to prevent access from personnel and the second fence is a
vehicle mitigating fence configured to withstand an impact from a vehicle.
13. The barrier of claim 12, wherein the anti-personnel fence is situated with
respect to the vehicle mitigating fence such that the anti-personnel fence
will be impacted first in the event of an impact by a vehicle.
14. The barrier of any preceding claim, wherein the second fence comprises a
plurality of wire ropes supported on said second series of posts.
15. The barrier of claim 14, wherein one or each end of the plurality of ropes
terminate in a ground terminal.
16. The barrier of claim 15, wherein the last post in said second series of posts
comprises means provided on or within said post for supporting said ropes.
17. The barrier of claim 16, wherein the ropes of the second fence enter the
terminal from the end post at an angle that enables the separation of the
first and second fences to remain substantially constant.