The present invention relates to a flexible post. The present invention particularly relates to a flexible post suitable for use in a wire cable safety barrier, such as used on roadsides and for separating road lanes .

There are a number of existing configurations of posts which are used in constructing wire cable safety barriers . They typically share the common features of being constructed from metal and having apertures for receiving the wire cables . The posts also typically include a number of components for locating and retaining the cables in the appropriate aperture .

The design, construction and materials of existing posts suffer from a number of disadvantages :

• the posts are typically constructed from metal or some other rigid material . This is a significant safety issue during road collisions , especially for motorcycle riders who have suffered serious injury or death when they or their motorcycle impacts the metal post;

• the rigidity and multicomponent construction of the post complicates replacement or repair of the posts when damaged. Typically, damaged posts will need to be replaced, requiring additional cost of materials and labour ;

• the complex construction of existing posts and the

requirement of a number of components in order to assemble the posts means that construction of new wire cable safety barriers is time intensive with attendant high labour costs .

It is therefore an object of the present invention to provide a flexible post suitable for use in a wire cable safety barrier which overcomes, or at least alleviates, one or more of the problems discussed above. According to the present invention there is provided a flexible post for use in a wire cable safety barrier, the flexible post being substantially elastically deformable and including a laminate formed by bonding together under heat and pressure an assembly of layers including at least one layer comprising uncured elastomer material , said post including one or more apertures for retaining therein respective wire cables of the wire cable safety barrier . The elastomer material may be rubber.

The present invention also provides a wire cable safety barrier incorporating one or more flexible posts as described above .

As used herein, the term "substantially elastically

deformable" means that the post may experience bending, twisting or other distortion upon application of a

sufficiently high force and then returns to substantially its original shape when the force ceases.

In an embodiment of the invention, the apertures are adapted to releasably retain therein the respective wire cables .

Preferably, they are adapted to release the wire cables upon impact of an object having sufficient force, such as a vehicle or a person in the course of a road accident.

The laminate is formed by bonding an assembly of layers, including at least one layer comprising uncured, wire

reinforced rubber, together under heat and pressure. The or each wire reinforced rubber layer may comprise a sheet formed by providing a wire containing sub layer between two uncured rubber sub layers . The rubber sheets may have Tensile strength varying between 10 and 15 MPa such as about 12 MPa. The elongation may be from 400% to 500%, such as about 450%. The hardness may vary from about 65 to 80 Shore A, such as about 68 Shore A. The density may be from about 1 to 1.5 g/cm ³ , such as about 1.2 g/cm ³ . Lamination may be conducted in a mold having heated platens . The temperature and pressure of lamination will depend on the softening temperature of the rubber and the number of layers in the laminate . The platen temperature may be at least 140°C, such as around 150°C. The pressure of lamination may be in excess of 100 psi, such as around 150 psi . The laminate may have between approximately 2 and 10 of the rubber sheets. Each wire reinforced rubber sheet may include a plurality of substantially parallel wires extending across the sheet. As mentioned embedded within the uncured rubber sheet is wire reinforcing. The wire reinforcing may conveniently be provided within a mesh structure within the rubber sheet.

The flexible post may have greater than 75% shape memory after deformation. Preferably, it has greater than 90% shape memory, such as greater than 95% shape memory.

The flexible post of the present invention may be erected by engagement with suitably shaped post socket which has been positioned and stabilised in the ground such as by concrete or other suitable means . The flexible post may then be inserted into the socket and is retained therein by the wire cables under tension. In the event of impact by an object with sufficient force, the flexible post is adapted to disengage from the socket. In addition, if the apertures are adapted to releasably retain wire cables , the post may also be disengaged from the cables .

In an embodiment of the flexible post of the invention, the post has two or more of the apertures which are arranged on opposing sides of the post. In this embodiment, the apertures may include lateral slots which extend inwardly from

respective lateral sides of the post. The lateral slots are configured to allow release of a respective wire cable upon impact with the post by a moving object, such as a vehicle or a person in the course of a road accident. Each aperture may include a retaining portion for retaining the wire cable in the aperture , and a passage extending from the mouth of the aperture to the retaining portion.

In one embodiment, the passage comprises the lateral slot and has a width which is narrower than the diameter of the wire cable . The post is sufficiently deformable to allow

separation of the walls of the passage to the extent necessary to allow the wire cable to be pushed through the passage and into the relatively wider retaining portion . Separation of the walls may be by way of deforming the walls, or by

deforming the post in order to space the walls from each other. When the wire cable is received in the retaining portion, the passage prevents the wire from being released from the retaining portion under normal usage conditions .

However, if the post and/or cable is subjected to a

sufficiently high force the cable will be released.

In another embodiment, the retaining portion includes a lip defining a narrowing of the passage at the entrance to the retaining portion. The narrowing may have a width which is less than the diameter of the wire cable, with the lip being sufficiently resilient to allow the wire cable to be pushed through the narrowing upon application of sufficient force thereto. The lip is configured such that, with the post erected in the wire cable safety barrier and the wire cable received in the retaining portion, the lip substantially prevents the wire from exiting the retaining portion under normal usage conditions . The lip may include a downwardly extending face or edge facing the narrowing which assists in guiding the wire cable through the narrowing. The lip may also include a laterally extending face or edge to assist in retaining the wire cable in the retaining portion . The aperture may be configured to facilitate the release of the wire cable from the aperture upon the application of a sufficiently high force to the post and/or wire cable. The force will typically be that applied due to a collision of a vehicle and/or a person with the wire cable safety barrier during the course of a road accident. The force should be sufficient to distort the resilient lip and thereby allow release of the cable from the aperture .

The passage which extends from the mouth of the aperture to the retaining portion may be substantially perpendicular to the longitudinal axis of the post. Alternatively, the passage may be inclined at an angle to the longitudinal axis of the post. In an embodiment, the passage extends downwardly, relative to the top of the post when erected vertically, at an angle of approximately 45° to the longitudinal axis. The narrowing may extend in a substantially downward direction, with the retaining portion being located below the narrowing. The retaining portion may also extend at least partially in a laterally outward direction from the narrowing.

In an embodiment of the post of the invention, there are three apertures provided on the post. Two of the apertures may be provided on one side and one positioned on the other side of the post, preferably between the other two apertures. The three apertures are preferably substantially evenly

longitudinally spaced from each other .

In another embodiment, there are four apertures provided in the post. Two apertures may be provided on one side and two on the otherside preferably in a staggered arrangement. The apertures may be integrally formed in the posts during the moulding process. Alternatively, the apertures may be formed after moulding the post, such as by cutting, for example with a high pressure water cutter or by punching out.

The post may have an elliptical or rectangular cross-section. Ά wire cable safety barrier incorporating one or more posts of the invention is constructed by positioning the desired number of post sockets into the ground and retaining them in the ground such as with concrete . The wire cables are then positioned within the respective apertures of the respective flexible posts . Each flexible post is fixed in place by tensioning the wire cables in a known manner . In the event of a collision between one or more flexible posts and a vehicle , the post is sufficiently flexible to bend away from the point of impact, and depending on the force of the impact, may disengage from its socket and/or the wire cables if the apertures have a releasable configuration. Accordingly, damage afforded by the flexible post to a vehicle or to a person is reduced as compared to the prior rigid posts , yet the wire cable/s remain in place and perform the desired function of keeping the vehicle on the roadway . Repair of the wire cable safety barrier may then be undertaken by simply reinserting the flexible post (or a new flexible post if the original post has been damaged) into the socket and/or repositioning the wire cables into the apertures. In this manner, material wastage and/or labour costs are minimised.

Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which :

Figure 1 is a perspective view of a flexible post in

accordance with a first embodiment of the present invention ;

Figure 2 is a cross-sectional view of the first embodiment post shown in Figure 1 along the line II-II;

Figure 3 is a detailed view of an aperture in the first embodiment of the post shown in Figure 1.

Figure 4 is a perspective view of a flexible post in

accordance with a second embodiment of the present invention . Figure 5 is a detailed view of the arrangement of apertures in the second embodiment of the post. With respect to Figure 1, there is shown a flexible post 10 suitable for use in the wire cable safety barrier . The flexible post is substantially elastically bendable . The flexible post is adapted to bend and/or distort in response to contact with a vehicle or person in the course of a road accident in order to allow the post to deflect from the path of movement of the vehicle or person and to allow release of the wire cables from the post and is adapted to return to its original shape thereafter . The flexible post is constructed from a laminate comprising a plurality of wire reinforced rubber layers as is shown in detail in the cross-sectional view in Figure 2. Each layer 12 of the laminate 14 comprises a rubber sheet 16 which is reinforced by a plurality of substantially parallel wires 20 extending across the sheet. The laminate 14 was formed by assembling two or more layers of the wire reinforced sheet 12 in an uncured state and applying heat and pressure to the assembly in order to bond the sheets together into the laminate. As is evident from Figure 2, the cross-section of the flexible post is substantially elliptical and this shape is imparted to the laminate by use of a suitably shaped mould during the bonding process .

As is shown in Figure 2 the embodiment of the flexible post has six wire reinforced rubber layers. The post shown in Figure 1 has greater than 90% shape memory after it is impacted with a vehicle or a person .

The flexible post 10 also includes three apertures 22 which are arranged on opposing sides of the post 10. Two apertures 22a, 22b are longitudinally spaced from each other on one side of the post with the third apertures 22c arranged between them on the other side of the post. Referring now to Figure 3, a detailed view of the aperture 22c is shown. The aperture 22c includes a retaining portion 24 for retaining a wire cable therein during use . The aperture 22c also includes a passage 26 extending downwardly from the mouth 28 of the aperture 24 at an approximately 45° angle to the longitudinal axis of the post 10. The wall of the retaining portion 24 includes a lip 30 which defines a narrowing 32 of the passage 26 at the entrance to the

retaining portion 24. The narrowing 32 extends substantially vertically downward to the entrance to the retaining portion 24. The narrowing 32 has a width w which is less than the diameter of the wire cable (not shown) . The lip 30 is sufficiently resilient to allow the wire cable to be pushed through the narrowing 32 upon application of sufficient force thereto, typically using manual force. The lip 30 includes a laterally extending retaining surface 34 which is located on the underside of the lip to assist in retaining the wire cable in the retaining portion 24. The lip 30 also includes a downwardly extending guiding surface 36 which assists in guiding the wire cable past the narrowing 32. The size of w will depend on the degree of flexibility of the lip 30.

However, w may be greater than 50% of the diameter of the wire cable. Preferably, w is between 50 and 90% of the diameter of the wire cable. In an embodiment, w is greater than 70% of the diameter of the wire cable .

Figures 4 and 5 illustrate a second embodiment of the flexible post, indicated generally at 110, in which similar reference numerals relate to similar parts of the first embodiment 10.

The second embodiment of the flexible post 110 differs from the first embodiment 10 only in respect of the shape and configuration of apertures 122a, 122b, 122c and 122d. The apertures are arranged on respective lateral sides of the flexible post in a staggered, longitudinally spaced

arrangement . Figure 5 provides a close up view of the aperture arrangement. Each aperture 122a, b, c, d comprises a respective retaining portion 124a, b, c, d for retaining a wire cable (not shown) therein during use and a respective passage 126a, b, c, d extending laterally outwards at substantially right angles to the longitudinal axis of the post 110. The post is

sufficiently flexible to enable walls 140a, b, c, d of each passage 126a, b, c, d to be separated apart from each other a sufficient distance to allow wire cable to be forced through the passage and into the retaining portion.

Many modifications may be made to the embodiment of the present invention described above , without departing from the spirit and scope of the present invention.