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Title:
SECURITY BARRIER ASSEMBLIES
Document Type and Number:
WIPO Patent Application WO/2017/194977
Kind Code:
A1
Abstract:
A secure barrier assembly (30) for resisting attack by an attack tool (82) such as a disc cutter, a cropping tool or grinding tool. The assembly (30) includes a plurality of elongate, longitudinally extending, substantially parallel ridge formations (34). Each formation (34) defines a trough (36).

Inventors:
HENMAN, Alastair (Zaun Limited, Steel Drive, Wolverhampton WV10 9ED, WV10 9ED, GB)
CHRISTIE, Adam (Zaun Limited, Steel Drive, Wolverhampton WV10 9ED, WV10 9ED, GB)
Application Number:
GB2017/051358
Publication Date:
November 16, 2017
Filing Date:
May 15, 2017
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
ZAUN LIMITED (Steel Drive, Wolverhampton WV10 9ED, WV10 9ED, GB)
International Classes:
E04H17/16; E02D29/02
Foreign References:
DE102013003189A12014-08-28
FR2909117A12008-05-30
US4530622A1985-07-23
GB2279388A1995-01-04
JPS57202552U1982-12-23
US5556080A1996-09-17
Other References:
None
Attorney, Agent or Firm:
IP-ACTIVE.COM LIMITED (The TechnoCentre, Coventry University Technology Park,,Puma Way, COVENTRY Warwickshire CV1 2TT, CV1 2TT, GB)
Download PDF:
Claims:
CLAIMS

1 . A security barrier assembly for resisting attack by an attack tool such as a disc cutter, a cropping tool or grinding tool, the assembly including a plurality of elongate, longitudinally extending, substantially parallel ridge formations, each formation defining a trough.

2. An assembly according to claim 1 , in which each trough extends in depth from a mouth to a base and has a depth dimension and a mouth width dimension.

3. An assembly according to claim 2, in which the depth dimension and the mouth width dimension are sized to prevent, in use, an attack tool from entering into the trough sufficiently far so as to permit the attack tool to attack the base.

4. An assembly according to claims 2 or 3, in which the mouth width dimension is at least 50mm, may be at least 60mm and optimally is at least 65mm.

5. An assembly according to any of claims 2 to 4, in which the mouth width dimension is no more than 90mm, may be no more than 80mm, and optimally is no more than 75mm. 6. An assembly according to any of claims 2 to 5, in which the depth dimension is at least 100mm, and may be at least 120mm and optimally is at least 140mm.

7. An assembly according to any of claims 2 to 6, in which the depth dimension is no more than 400mm, and may be no more than 280mm and optimally is no more than 160mm.

8. An assembly according to any of claims 2 to 7, in which the ratio of the depth dimension to the mouth width dimension is at least 1 : 1 , and optimally, the depth: mouth width ratio may be at least 2: 1 . 9. An assembly according to any of claims 2 to 8, in which each trough tapers inwardly in width from the mouth down to the base.

10. An assembly according to any of claims 2 to 9, in which each formation comprises a base wall, which has a width and is located at the base of the trough and each formation includes side walls extending from the base wall, each side wall extending to a top vertex.

1 1 . An assembly according to claim 10, in which each formation includes a peak wall, each side wall extends between a respective base wall and a respective peak wall, and each top vertex is located between a respective side wall and a respective peak wall.

12. An assembly according to claim 1 1 , in which the peak wall has a width which is similar to the base width.

13. An assembly according to claim 12, in which the peak wall width is no greater than the mouth width dimension.

14. An assembly according to any of claims 1 1 to 13, in which the top vertex is a nominal vertex in the case in which the formation includes a chamfer or radius between the peak wall and the respective side wall.

15. An assembly according to any of claims 10 to 14, in which the mouth extends between adjacent top vertices.

16. An assembly according to any of claims 10 to 15, in which each formation includes an internal base vertex between the base wall and the respective side wall.

17. An assembly according to claim 16, in which the base vertex is a nominal vertex in the case in which the formation includes a chamfer or radius between the base wall and the respective side wall.

18. An assembly according to claims 16 or 17, in which the base extends between adjacent internal base vertices.

19. An assembly according to claim 1 1 or any claim dependent thereon, in which the side walls are angled at a taper angle to a normal of the base walls and/or the peak walls, which is an oblique angle.

20. An assembly according to claim 19, in which the taper angle is no less than 4° and may be no less than 5°.

21 . An assembly according to claims 19 or 20, in which the taper angle is no more than 15° and may be no more than 10°.

22. An assembly according to any of the preceding claims, in which the ridge formations comprise a corrugated surface.

23. An assembly according to claim 22, in which the assembly includes a corrugated layer, and the corrugated surface comprises part of the corrugated layer.

24. An assembly according to claim 23, in which the corrugated layer comprises a mesh material.

25. An assembly according to claim 24, in which the mesh material is formed by a manufacturing process to comprise the ridge formations.

26. An assembly according to claims 24 or 25 when dependent on claim 1 1 or any claim dependent thereon, in which the mesh material is formed so that the ridge formations are formed on both a front face and a back face of the corrugated layer, with the back face being the reverse of the front face, so that the peak walls of one face are the base walls of the other face and vice versa. 27. An assembly according to any of claims 24 to 26, in which the mesh material comprises a plurality of first members, which are arranged substantially parallel to one another so that they do not cross one another and are spaced apart at a first spacing. 28. An assembly according to claim 27, in which the first members extend along a first direction.

29. An assembly according to any of claims 24 to 28, in which the mesh material comprises a plurality of second members which are arranged substantially parallel to one another so that they do not cross one another and are spaced apart at a second spacing.

30. An assembly according to claim 29 when dependent on claim 28, in which the second members extend along a second direction, which is different to the first direction and may be at 90° to the first direction.

31 . An assembly according to claims 29 or 30 when dependent on claims 27 or 28, in which the first and second members are interconnected by fixing together at contact points, possibly by welding.

32. An assembly according to any of claims 29 to 31 when dependent on claim claims 27 or 28, in which the first spacing is different to the second spacing and may be smaller than the second spacing. 33. An assembly according to claim 28 or any claim dependent thereon, in which the first direction extends substantially along the length of the ridge formations.

34. An assembly according to claim 23 or any claim dependent thereon, in which the assembly includes a non-corrugated rear layer, which is substantially planar, and is located adjacent to the corrugated layer, and is fixed adjacent to the corrugated layer.

35. An assembly according to claim 23 or any claim dependent thereon, in which the assembly includes a non-corrugated front layer, which is substantially planar, and is located adjacent to the corrugated layer, and is fixed adjacent to the corrugated layer.

36. An assembly according to claim 35 when dependent on claim 34, in which the front layer is located adjacent to the corrugated layer, against an opposite face of the corrugated layer to the rear layer. 37. An assembly according to claims 34, 35 or 36, in which the rear layer and/or the front layer comprise mesh material.

38. An assembly according to claim 37 when dependent on claim 24 or any claim dependent thereon, in which the rear layer and/or the front layer comprise substantially the same mesh material as the corrugated layer.

39. An assembly according to claim 38 when dependent on claims 34, 35 or 36, when dependent in turn on claims 27 and 29, in which the directions of the first and second members of the rear and front layers are substantially at 90° to those of the corrugated layer.

40. An assembly according to claims 34 or 35 or any claim dependent thereon, when dependent on claim 23 or any claim dependent thereon, in which the assembly includes fastenings, which fasten the corrugated layer and the rear and/or front layers together.

41 . An assembly according to claim 40, in which the fastenings comprise bolts, nuts and washers.

42. An assembly according to claims 40 or 41 , in which the fastenings are located in a pattern of horizontal and vertical spacings.

43. An assembly according to claim 42, in which the pattern is a regular repeating pattern.

44. An assembly according to claim 42 or 43, in which the horizontal spacings and the vertical spacings are substantially similar. 45. An assembly according to any of claims 40 to 44 when dependent on claims 1 1 , 23 and 34 or 35, in which the fastenings include peak fastenings, which fasten the corrugated layer and the rear and/or front layers together through the peak walls. 46. An assembly according to any of claims 40 to 45 when dependent on claims 10, 23 and 34, in which the fastenings include base fastenings, which fasten the corrugated layer and the rear layer together through the base walls. 47. An assembly according to claims 27 or 29, in which the mesh members are in the form of rods or wires, which may be formed of metal, possibly steel, possibly high tensile steel, which may be galvanised.

48. A method of preventing or hindering unauthorised access, the method including providing a security barrier assembly for resisting attack by an attack tool such as a disc cutter, a cropping tool or grinding tool, the assembly including a plurality of elongate, longitudinally extending, substantially parallel ridge formations, each formation defining a trough.

49. A method according to claim 48, in which the assembly includes any of the features defined in any of claims 1 to 47.

Description:
Security Barrier Assemblies

The present invention relates to security barrier assemblies, particularly but not exclusively security barrier assemblies for resisting attack by an attack tool such as a disc cutter, cropping tool or grinding tool.

Conventionally, it is known to provide barrier assemblies such as security fences for preventing or hindering unauthorised access. The assemblies can comprise substantially flat fence panels, supported by spaced upright posts. In some arrangements, the fence is topped by a roll of barbed wire, and/or includes an angled overhang to deter intruders from climbing over. Typically, each panel comprises a mesh of steel wire strands, which may be woven or welded together. The increasing availability of portable and powerful cutting, cropping and grinding hand tools provides intruders with the means of cutting or breaking through the wire strands relatively quickly. This can mean that although security personnel may be alerted by alarms, security cameras or the noise of the cutting process, the fabric of the barrier provides inadequate delay time for an effective response. Typically, security barriers may be tested in accordance with recognised standards to obtain a security rating. The rating is dependent on the tools and time required for penetration. Higher ratings require the fence to provide resistance to more aggressive tools for longer delay periods.

According to a first aspect of the present invention, there is provided a security barrier assembly for resisting attack by an attack tool such as a disc cutter, a cropping tool or grinding tool, the assembly including a plurality of elongate, longitudinally extending, substantially parallel ridge formations, each formation defining a trough. Possibly, each trough extends in depth from a mouth to a base. Possibly, the trough has a depth dimension and may have a mouth width dimension. Possibly, the depth dimension and the mouth width dimension are sized to prevent, in use, an attack tool from entering into the trough sufficiently far so as to permit the attack tool to attack the base.

Possibly, the mouth width dimension is at least 50mm, may be at least 60mm and optimally is at least 65mm. Possibly, the mouth width dimension is no more than 90mm, may be no more than 80mm, and optimally is no more than 75mm.

Possibly, the depth dimension is at least 100mm, and may be at least 120mm and optimally is at least 140mm. Possibly, the depth dimension is no more than 400mm, and may be no more than 280mm and optimally is no more than 160mm.

Possibly, the ratio of the depth dimension to the mouth width dimension is at least 1 : 1 . Possibly, the depth: mouth width ratio is at least 1 .2: 1 and may be at least 1 .4: 1. Optimally, the depth: mouth width ratio may be at least 2: 1 .

Possibly, each trough tapers inwardly in width from the mouth down to the base.

Possibly, each formation comprises a base wall, which may have a width and may be located at the base of the trough. Possibly, each formation includes side walls extending from the base wall. Each side wall may extend to a top vertex.

Possibly, each formation includes a peak wall. Possibly, each side wall extends between a respective base wall and a respective peak wall, and each top vertex may be located between a respective side wall and a respective peak wall.

Possibly, the peak wall has a width which is similar to the base width. Possibly, the peak wall width is no greater than the mouth width dimension.

The top vertex may be a nominal vertex in the case in which the formation includes a chamfer or radius between the peak wall and the respective side wall.

The mouth may extend between adjacent top vertices.

Possibly, each formation includes an internal base vertex between the base wall and the respective side wall. The base vertex may be a nominal vertex in the case in which the formation includes a chamfer or radius between the base wall and the respective side wall.

Possibly, the base extends between adjacent internal base vertices.

Possibly, the side walls are angled at a taper angle to a normal of the base walls and/or the peak walls, which may be an oblique angle. Possibly, the taper angle is no less than 4° and may be no less than 5°. Possibly, the taper angle is no more than 15° and may be no more than 10°.

Possibly, the ridge formations comprise a corrugated surface. Possibly, the assembly includes a corrugated layer, and the corrugated surface comprises part of the corrugated layer. Possibly, the corrugated layer comprises a mesh material, which may be formed by a manufacturing process to comprise the ridge formations. Possibly, the mesh material is formed so that the ridge formations are formed on both a front face and a back face of the corrugated layer, with the back face being the reverse of the front face, so that the peak walls of one face are the base walls of the other face and vice versa.

Possibly, the mesh material comprises a plurality of first members, which may be arranged substantially parallel to one another so that they do not cross one another and may be spaced apart at a first spacing. Possibly, the first members extend along a first direction.

Possibly, the mesh material comprises a plurality of second members which are arranged substantially parallel to one another so that they do not cross one another and may be spaced apart at a second spacing. Possibly, the second members extend along a second direction, which may be different to the first direction and may be at 90° to the first direction.

Possibly, the first and second members are interconnected by fixing together at contact points, possibly by welding. Possibly, the first spacing is different to the second spacing and may be smaller than the second spacing.

Possibly, the first direction extends substantially along the length of the ridge formations.

Possibly, the assembly includes a non-corrugated rear layer, which may be substantially planar, and may be located adjacent to the corrugated layer, and may be fixed adjacent to the corrugated layer. Possibly, the assembly includes a non-corrugated front layer, which may be substantially planar, and may be located adjacent to the corrugated layer, and may be fixed adjacent to the corrugated layer. Possibly, the front layer is located adjacent to the corrugated layer, against an opposite face of the corrugated layer to the rear layer.

Possibly, the rear layer and/or the front layer comprise mesh material and may comprise substantially the same mesh material as the corrugated layer.

Possibly, the directions of the first and second members of the rear and front layers are substantially at 90° to those of the corrugated layer.

Possibly, the assembly includes fastenings, which may fasten the corrugated layer and the rear and/or front layers together. Possibly, the fastenings comprise bolts, nuts and washers. Possibly, the fastenings are located in a pattern of horizontal and vertical spacings. Possibly, the pattern is a regular repeating pattern. Possibly, the horizontal spacings and the vertical spacings are substantially similar.

Possibly, the fastenings include peak fastenings, which fasten the corrugated layer and the rear and/or front layers together through the peak walls. Possibly, the fastenings include base fastenings, which fasten the corrugated layer and the rear layer together through the base walls.

Possibly, the mesh members are in the form of rods or wires, which may be formed of metal, possibly steel, possibly high tensile steel, which may be galvanised.

According to a second aspect of the present invention, there is provided a method of preventing or hindering unauthorised access, the method including providing a security barrier assembly for resisting attack by an attack tool such as a disc cutter, a cropping tool or grinding tool, the assembly including a plurality of elongate, longitudinally extending, substantially parallel ridge formations, each formation defining a trough. Possibly, the assembly includes any of the features described in any of the preceding statements or following description. Possibly, the method includes any of the steps described in any of the preceding statements or following description.

An embodiment of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:-

Fig. 1 is a perspective view of a known security barrier assembly not according to the invention;

Fig. 2 is a relatively enlarged view of a part of the assembly of Fig. 1 , as indicated by the oval labelled II in Fig. 1 ;

Fig. 3 is a perspective view of a security barrier assembly according to the invention;

Fig. 4 is a plan view from above of the assembly of Fig. 3;

Fig. 5 is a front view of the assembly of Figs. 3 and 4;

Fig. 6 is a side view of the assembly of Figs 3 to 5;

Fig. 7 is a plan view from above of the assembly of Figs. 3 to 6 in a first stage of an attack by an attack tool; and

Fig. 8 is a plan view from above of the assembly of Figs. 3 to 6 in a second stage of the attack by the attack tool.

Fig. 1 shows a known fence assembly 10 including spaced substantially vertical supports 12 in the form of rectangular hollow section posts and panels 14 which are fixed to the supports 12.

Each panel 14 is formed of a mesh material 16 which includes a plurality of spaced substantially parallel first mesh members 18 in the form of rods or wires, which extend along a first direction 60, and a plurality of spaced substantially parallel second mesh members 22 in the form of rods or wires, which extend along a second direction 62, which is substantially at 90° to the first direction. The panels 14 and the mesh material 16 is usually planar.

In the example shown, the first direction 60 is substantially horizontal and the second direction 62 is substantially vertical.

The first and second mesh members 18, 22 are located adjacent to each other and fixed together by welding at contact points.

The first mesh members 18 are spaced at a first spacing 24, and the second mesh members 22 are spaced at a second spacing 26, in each case the spacings 24, 26 being the minimum distance between corresponding parts (eg centre to centre) of the neighbouring mesh members 18, 22 respectively.

In the example shown, the first spacing 24 of the first (horizontal) mesh members 18 is smaller than the second spacing 26 of the second (vertical) mesh members 22. Thus the number density (ie number of members per unit distance) of first members 18 extending horizontally is greater than the number density of second members 22. Such an arrangement is typical of high security fence panels.

The wire mesh 16 defines mesh apertures 28 which are defined by the first and second mesh members 18, 22. In the example shown, each mesh aperture 28 is rectangular and elongate along the first (horizontal) direction. In one example, the first and second mesh members 18, 22 are in the form of wire rods of 4mm diameter. The first spacing 24 could be approximately 12.7mm and the second spacing 26 could be 76.2 mm. With these dimensions, the first spacing 24 prevents the insertion of fingers and most tools thus preventing climbing.

Figs. 3 to 8 show an embodiment of the invention, a secure barrier assembly 30 for resisting attack by an attack tool 82 such as a disc cutter, a cropping tool or grinding tool, the assembly 30 including a plurality of elongate, longitudinally extending, substantially parallel ridge formations 34. Each formation 34 defines a trough 36.

Each trough 36 extends in depth from a mouth 42 to a base 40 and has a depth dimension 38 and a mouth width dimension 44.

Each trough 36 tapers inwardly in width from the mouth 42 down to the base 40. Each formation 34 comprises a base wall 46, which has a width 74 and is located at the base 40 of the trough 36, a peak wall 48, and side walls 50 extending from the base wall 46 to neighbouring peak walls 48.

Each formation 34 includes a top vertex 52 between the peak wall 48 and the respective side wall 50.

The mouth 42 extends between the adjacent top vertices 52 of neighbouring peak walls 48. Each formation 34 includes an internal base vertex 54 between the peak wall 48 and the respective base wall 46.

The base 40 extends between adjacent internal base vertices 54. The trough base width 74 is the dimension between the adjacent internal base vertices 54.

The side walls 50 are angled at a taper angle 56 to a normal of the base walls 46 and the peak walls 48. The taper angle 56 is an oblique angle. In one example, the taper angle 56 could be no less than 4°, and could be no less than 5°. In one example, the taper angle 56 could be no more than 15° and could be no more than 10°. In one example, the mouth width dimension 44 could be at least 50mm, more desirably could be at least 60mm and optimally could be at least 65mm. In one example, the mouth width dimension 44 could be no more than

90mm, more desirably could be no more than 80mm, and optimally could be no more than 75mm.

In one example, the depth dimension 38 could be at least 100mm, more desirably could be at least 120mm and optimally could be at least 140mm.

In one example, the depth dimension 38 could be no more than 400mm, more desirably could be no more than 280mm and optimally could be no more than 160mm.

The ratio of the depth dimension 38 to the mouth width dimension 44 is at least 1 : 1 . In one example, the depth: mouth width ratio could be at least 1 .2: 1 .

In another example, the depth: mouth width ratio could be at least 1 .4: 1 . Optimally, the depth: mouth width ratio could be at least 2: 1 .

In one example, the mouth width dimension 44 could be approximately 70mm, the depth dimension 38 could be approximately 100mm, the base and peak wall widths 74, 76 could be approximately 40mm, the taper angle 56 could be approximately 8.6° and the ratio of the depth dimension 38 to the mouth width dimension 44 could be approximately 1 .43: 1 . In a further example, the mouth width dimension 44 could be approximately 70mm, the depth dimension 38 could be approximately 150mm, the base and peak wall widths 74, 76 could be approximately 40mm, the taper angle 56 could be approximately 5.7° and the ratio of the depth dimension 38 to the mouth width dimension 44 could be approximately 2.14: 1 .

In the example shown, the ridge formations 34 comprise a corrugated surface 32. The assembly 30 includes a corrugated layer 58, and the corrugated surface 32 comprises part of the corrugated layer 58.

In one example, the corrugated layer 58 comprises mesh material 16A. Initially, in a planar condition, the corrugated mesh material is similar to the known mesh material 16 of the security barrier assembly 10 shown in Figs. 1 and 2. Thus, the corrugated layer mesh material 16A comprises first members 18A and second members 22A which extend respectively in first and second directions 60A, 62A. However, in the security barrier assembly 30 of the invention, the mesh material 16A is formed by a manufacturing process to comprise the ridge formations 34.

As will be seen from the drawings, the mesh material 16A is formed so that the ridge formations 34 are formed on both a front face 78 and a back face 80 of the corrugated layer 58, with the back face 80 being the reverse of the front face 78, so that the peak walls 48 of one face are the base walls 46 of the other face and vice versa. As shown in the drawings, the peak wall 48 has a width 76 which is similar to the trough base width 74, so that the corrugated layer 58 is substantially reversible. This also has the advantage of simplifying manufacturing.

The assembly 30 includes a non-corrugated rear layer 64, which is substantially planar, and is fixed adjacent to the corrugated layer 58.

In the example shown, the assembly 30 includes a non-corrugated front layer 66, which is substantially planar, and is fixed adjacent to the corrugated layer 58, against an opposite face of the corrugated layer 58 to the rear layer 64.

The rear layer 64 and the front layer 66 respectively comprise rear layer mesh material 16B and front layer mesh material 16C. In the example shown, the rear layer mesh material 16B and the front layer mesh material 16C are both substantially the same as the mesh material 16 of the known assembly 10 and the mesh material 16A of the corrugated layer 58 in its planar condition.

The rear layer mesh material 16B comprises first members 18B and second members 22B which extend in first and second directions 60B, 62B.

The front layer mesh material 16C comprises first members 18C and second members 22C which extend in first and second directions 60C, 62C.

The directions of the first and second members of the rear and front layers 64, 66 are substantially at 90° to those of the corrugated layer 58. The assembly 30 includes fastenings 68, which fasten the corrugated layer 58, the rear layer 64 and the front layer 66 together. The fastenings 68 could comprise bolts, nuts and washers. The fastenings 68 are located in a regular repeating pattern of substantially similar horizontal and vertical spacings 70, 72.

The fastenings 68 include peak fastenings 90, which fasten the corrugated layer 58 and the rear and/or front layers 64, 66 together through the peak walls 48. The fastenings 68 include base fastenings 88, which fasten the corrugated layer 58 and the rear layer 64 together through the base walls 46. Figs. 7 and 8 show the security barrier assembly 30 of the invention in use and under attack by an attack tool 82 such as a disc cutter, comprising a body 84 and a disc 86. In use, the assembly 30 could be mounted to spaced substantially vertical supports 12.

In order to penetrate the assembly 30, it is necessary for the intruder to cut through a certain number of the first or second members 18, 22 to form, for example, an aperture in the assembly 30. The easiest and quickest way for the intruder to do this is by cutting through the less number dense second members 22 and then opening up the slit thus formed. This is a relatively easy task in the known assembly 10. For example, in the known assembly 10, to form a slit which is 500mm long would require the cutting of six second members 22.

In trying to penetrate the inventive assembly 30, the intruder must first attack the second members 22C of the front layer 66 to form a slit as described above. In Fig. 7, a slit has been formed for the disc 86 of the disc cutter 82 to penetrate, but the body 84 of the disc cutter cannot penetrate further because the slit has not been opened sufficiently. The spaced fastenings 68 permit only limited opening of the slit formed and thus it is likely to be necessary for the intruder to cut through at least one fastening 68, and more possibly two.

It will also be apparent from Fig. 7, that, having cut through some of the second members 22C of the front layer 66, the disc 86 almost immediately encounters the higher number density first members 18A at the peak walls 48 of the corrugated layer 58. The corrugated layer 58 first members 18A thus prevent or hinder penetration of the disc 86 into the trough 36.

Fig. 8 shows the situation at a later stage of the attack in which the front layer 66 has been removed. The width 44 of the trough mouth 38 is of a size which prevents entry of the body 84 into the trough 36 and the depth 38 of the trough 36 is deep enough so that the disc 86 cannot reach the base wall 46, the rear layer 64, or the base fastenings 88. It is therefore necessary for the intruder to cut through the corrugated layer 58. If the intruder forms a slit by cutting through some of the second members 22A in one of the peak walls 48, then he/she will need to cut through the higher density first members 18B of the rear layer 64, but will not then be able to open any slit formed out without further extensive cutting. Thus, the depth dimension 38 and the mouth width dimension 44 are sized to prevent, in use, the attack tool 82 from entering into the trough 36 sufficiently far so as to permit the attack tool 82 to attack the base 40.

The Applicant has realised that the security rating is increased as the mouth width dimension 44 is reduced and the trough depth dimension 38 is increased. However, reducing the mouth width dimension 44 and increasing the trough depth dimension 44 both increase the material usage, weight and cost per unit barrier area. The examples given represent the optimum balance of dimensions to maximise the delay gained in penetration of an attack tool 82 while minimising material usage, weight and cost.

In an alternative embodiment, a security barrier assembly could be provided without the front layer 66, as shown in Fig. 8. Thus, the security barrier assembly 30 of the invention provides a number of advantages over conventional arrangements. The ridge formations 34 are sized to prevent penetration of the body 84 of the attack tool 82 into the troughs 36 and prevent attack upon the base wall 46 and the rear layer 64. In addition, the directions of the first and second members of the rear and front layers 64, 66 are substantially at 90° to those of the corrugated layer 58, which means that there are no clear and easy routes to form useful size slits. These features serve to increase the attack time to achieve penetration significantly. A further advantage is that the security barrier of the invention utilises known and standardised mesh material. Various other modifications could be made without departing from the scope of the invention. The security barrier assembly and its components could be of any suitable size and shape, and could be formed of any suitable material (within the scope of the specific definitions herein). In one example, the corrugated layer 58 could be formed of the mesh material 16, but the front and rear layers 64, 66 could be formed of different materials and/or of a different construction eg solid, woven, wood, expanded metal, sheet metal, plastics materials, toughened glass etc. In another example, the assembly could comprise a substantially solid layer which includes a surface having a plurality of elongate, longitudinally extending, substantially parallel ridge formations, each formation defining a trough. The assembly of the invention could comprise part of another structure, for example, a gate, wall, floor or ceiling, and could be incorporated into the structural fabric of a building.

The mesh materials could have different numbers and arrangements of members from that described. The first and second members could be of different spacings from that described. In one example, the first and second members could have similar or the same spacings.

The top and base vertices 52, 54 could be nominal vertices in the cases in which the formation 34 includes a chamfer or radius (not shown) between the peak wall 48 and the respective side wall 50 and/or the base wall 46 and the respective side wall 50. The peak walls 48 and base walls 46 could differ in width. However, the peak wall width 76 should be no greater than the mouth width 44, as otherwise this would provide an attack route. In another example, the ridge formations 34 could be formed without peak walls 48, so that the respective side walls 50 meet at one respective top vertex 52. In yet another example, the ridge formations 34 could be formed without base walls 46, so that the respective side walls 50 meet at one respective base vertex 54.

In another example, the trough 36 might not taper inwardly from the mouth 42 to the base 40. The taper angle 56 might be 0°, so that the side walls 50 are at 90° to the base and peak walls 46, 48. In another example, the trough 36 might taper outwardly from the base to the mouth in the form of a dovetail.

In another example, the assembly 10 could include a plurality of corrugated layers 58 located between the front and rear layers 56, 54. The corrugated layers 58 could be located alongside each other, or the assembly 10 could include intermediate layers (not shown) similar to the front and rear layers 56, 54 located between the corrugated layers 58.

In another example, the ridge formations 34 could be formed separately and fixed to a support surface (not shown) to form the corrugated surface 32.

There is thus provided a security barrier assembly with a number of advantages over conventional arrangements.