AU2015100857A4 - A Frangible Pole Assembly - Google Patents

Abstract

A frangible pole assembly comprising a ground sleeve that is at least partially inserted into the ground, and a pole that can slide at least partially within the ground sleeve to hold the pole in place, the pole being provided with circumferential longitudinal flutes at least in the region where the pole contacts an upper edge of the ground sleeve. m ft x :: lal xb ',X: AM\ Sm 6 m -X.:.X. sm MEMEN, 'm . RON, M X mr. "x 0:11 Fi gure I

Description

A FRANGIBLE POLE ASSEMBLY TECHNICAL FIELD [0001] The present invention relates to a frangible pole and particularly to a frangible sign pole that can be used on highways, airports and elsewhere. BACKGROUND ART [0002] The dangers associated with vehicles striking a pole are well known. Highways and roadways are provided with signs, poles and the like which are positioned on the side of the road. If such a sign/pole is struck by a car, death and injury can result. [0003] For this reason, there have been many attempts made to provide some form of safety pole or safety sign. Thus, it is known to provide a pole which is relatively lightweight and which can simply break or shatter when struck by a car thereby reducing injury to the car occupants. However, the main disadvantage with this type of arrangement is the time that is required to replace the pole. [0004] To overcome this disadvantage, many attempts have been made to provide some form of pole that can be more easily replaced should the pole become damaged or destroyed. The main focus has been on the ability to quickly replace the pole. Thus, it is well known to provide a first member that stays in the ground, and a pole that is fixed to the first member by some form of sacrificial pin and the like. If the pole is struck, the sacrificial pin will break, the pole and pin will be destroyed but the first member stays intact. It is considered that the pole and sacrificial pin can be more easily replaced if the ground member (the first member) is protected. [0005] There have been many variations to this type of arrangement, but each still requires some form of sacrificial pin or other member that is broken or sheared when the pole is struck. The main disadvantage is that it still takes some time to replace the pole that has a sacrificial pin or other member, as assembly and attachment of the sacrificial pin can take some time. [0006] There would be an advantage if it were possible to provide some form of replaceable pole which did not require a sacrificial pin or other member. [0007] Another consideration, particularly for poles that support large signage, is that the pole must be able to take wind load on the sign without breaking. Some sacrificial members will break under high wind loads which is not desirable.

[0008] It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. SUMMARY OF INVENTION [0009] The present invention is directed to a frangible pole, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice. [0010] With the foregoing in view, the present invention in one form, resides broadly in a frangible pole assembly, the assembly comprising a ground sleeve that is at least partially inserted into the ground, a pole that can slide at least partially within the ground sleeve to hold the pole in place, the pole being provided with circumferential longitudinal flutes at least in the region where the pole contacts an upper edge of the ground sleeve and a restraint assembly to attach the pole to the ground sleeve to prevent separation of the pole from the ground sleeve after the pole has broken. [0011] In an alternative form, the present invention resides in a frangible pole assembly, the assembly comprising a ground sleeve that is at least partially inserted into the ground, a pole that can slide at least partially within the ground sleeve to hold the pole in place, the pole being provided with circumferential longitudinal flutes at least in the region where the pole contacts an upper edge of the ground sleeve and a point of weakness formed in the pole above the ground sleeve. [0012] In still another form, the present invention resides in a method of erecting a frangible pole assembly, the assembly comprising a ground sleeve that is at least partially inserted into the ground, a pole that can slide at least partially within the ground sleeve to hold the pole in place, the pole being provided with circumferential longitudinal flutes at least in the region where the pole contacts an upper edge of the ground sleeve and a point of weakness formed in the pole above the ground sleeve, the method including the step of orienting the pole such that the point of weakness is oriented toward a most likely direction of impact. [0013] In one preferred embodiment, the upper edge of the ground sleeve acts as a sheer point and depending upon the particular molecular structure of the alloy of material used, will bend the pole at the point of impact and will ultimately shear and break at the top of the ground sleeve. The flutes on the pole are designed to further assist in the breakaway process by reducing the external surface area of the pole in contact with the ground sleeve. [0014] Ian alternative embodiment, the provision of the point of weakness creates a shear point in the pole to encourage breaking of the pole at or through that point when the pole suffers an impact. [0015] It is found that the arrangement of circumferential flutes on the pole enables the pole to be sheared off when struck with little or no damage to the ground sleeve. Typically, the pole is sheared at or adjacent the upper edge of the ground sleeve. Also, a sacrificial pin and the like is not required. The arrangement of the flutes seems to enable the pole to be broken without substantial damage to the ground sleeve and in a manner that is safer to vehicles that may strike the pole compared with a metal pole that is simply concreted directly into the ground. [0016] The flutes should be provided on the poles at least in a region where the pole contacts the upper edge of the ground sleeve. However, as it is preferred that the pole is extruded from aluminium, it may be effective to simply extrude the pole with the flutes extending along the entire length of the pole. [0017] It is preferred that the flutes extend entirely about the pole and on the outer surface of the pole. The flutes may be spaced apart from each other by a distance of between 2-20 millimetres. The flutes may have a depth of between 1-5 millimetres, and a width of between 3 15 millimetres. The flutes may be substantially rectangular when viewed in plan. [0018] To assist in providing the pole with frangible properties, it is preferred that the pole is manufactured from a material that can shear when struck by a load. It is found that aluminium is a suitable material and it is therefore preferred that the pole is manufactured from aluminium. However, it is envisaged that other metals and possibly metal alloys may have desirable properties including alloys containing zinc, nickel, lead, copper, iron and the like. [0019] In a particularly preferred embodiment, the pole is made from structural grade 6261 T5 or T6 aluminium. A preferred material has a yield strength of approximately 275MPa. [0020] It is also preferred that the pole is hollow to reduce weight and materials. [0021] Another advantage in using aluminium is that the pole has less weight than a typical steel pole and therefore more poles can be loaded onto a truck, and the poles can be handled more easily. Also, aluminium is more resistant to corrosion and environmental degradation compared to steel poles.

[0022] The length of the pole can vary depending on its use. The typical length will be anywhere between 1-6 metres or even longer and it is not considered that the invention should be limited to any particular length of the pole. [0023] The pole will usually be cylindrical. However there may be an advantage in providing the pole with other configurations such as slightly oval, rectangular, or other irregular shapes. [0024] If the pole is cylindrical, the outside diameter of the pole may be anywhere between 50-150 millimetres and preferably between 60-130 millimetres and most preferably between 60 120 millimetres. [0025] The wall thickness of the pole will vary depending on the diameter of the pole, the wind loading on the pole, the size and weight of the signage or other item that is attached to the pole, etc. However, it is envisaged that the wall thickness will be between 3-7 millimetres and preferably between 3-6 millimetres and most preferably between 3.75-5.5 millimetres. [0026] The pole may be provided with an upper end cap to prevent water from entering into the pole. This cap may be made of plastic, rubber, metal and the like. [0027] The ground sleeve may be made of any suitable material and it is preferred that the ground sleeve is made of metal such as aluminium. The ground sleeve will typically have an internal diameter or cross-section which is slightly larger than the external diameter or cross section of the pole to enable the pole to slide into the ground sleeve, although a snug or interference fit is preferred. [0028] Suitably, the pole will be cylindrical and therefore the ground sleeve will also be cylindrical. The ground sleeve may have a length of between 20-100 centimetres depending on the dimensions of the pole, etc. The ground sleeve will normally have an internal diameter of between 50-150 millimetres but the diameter should be to enable the pole to slide within the ground sleeve. [0029] In use, the ground sleeve is positioned in the ground and typically in such a manner that the upper edge of the ground sleeve is slightly spaced above the ground, the spacing typically being between 3-10 centimetres. [0030] The ground sleeve can have a wall thickness of between 3-10 millimetres although this can vary to suit.

[0031] The ground sleeve may be provided with one or more fastener to fix the pole into the ground sleeve. Each fastener may comprise a bolt, although no limitation should be placed on the innovation merely by describing a bolt and the fastener may comprise a screw, a clamp, a wedge, a locking pin and the like. [0032] If desired, a separate wedge may be provided to further hold the pole within the ground sleeve, although this wedge is not the same as a sacrificial pin as it does not break or shatter in a sacrificial manner. [0033] The ground sleeve may be provided with means to prevent or to resist rotation of the pole within the ground sleeve. If the pole is cylindrical and the ground sleeve is cylindrical, one way in which this can be achieved is to provide a small bead or projection in the ground sleeve and which can engage in a flute on the pole thereby preventing the pole from rotating within the ground sleeve. If necessary and more preferred, more than one such bead or projection can be provided. In practice, at least two beads or protections will be provided. [0034] If the ground sleeve is made of extruded aluminium, the bead or projection can form part of the extrusion. [0035] In particular, it is preferred that the ground sleeve will be provided with a mounting portion for mounting the fasteners thereto. Preferably, a mounting portion will include a substantially U-shaped wall portion located in a wall of the ground sleeve. Preferably, the ground sleeve will be circular in order to provide frangibility in multiple directions and the mounting portion is provided over at least a portion of the height of the ground sleeve. [0036] Typically, the substantially U-shaped mounting portion will extend over the height of the ground sleeve although it may be restricted to a particular portion of the ground sleeve. In particular, it is preferred that and the U-shaped mounting portion will be provided adjacent to the top edge of the ground sleeve and be located above the ground surface when the sleeve is properly installed. [0037] Typically, the U-shaped mounting portion includes a pair of walls extending perpendicularly away from the solid wall of the ground sleeve and an outer wall linking the pair of walls. This configuration preferably forms the U-shaped channel in the side wall of the ground sleeve. Typically, the mounting portion is located outside of the internal shape of the ground sleeve so as not to obstruct insertion and removal of the pole therefrom. [0038] The fasteners used to fix the pole relative to the ground sleeve will preferably be mounted through the mounting portion, and particularly, through the outer wall approximately perpendicularly to the pole. [0039] The mounting portion will typically be integrally formed with the ground sleeve typically by extrusion. [0040] The frangible pole of the present invention may include a transition shoe. Where provided, the transition shoe will typically be located adjacent to the mounting portion and it is particularly preferred that the transition shoe is located between the mounting portion and the exterior surface of the pole. Even more preferred is that the transition shoe is located between the fasteners and the pole. [0041] Typically in use, the end of the preferred fasteners will abut the transition shoe which in turn abuts the pole in order to fix the pole in position by applying a clamping force. This also has the effect of spreading the load applied by the fasteners over a greater area of the pole. [0042] The transition shoe of the present invention will typically include a substantially planar shoe portion for insertion between the mounting portion of the ground sleeve and the pole. [0043] The transition shoe will also typically be provided with a gripping portion at or adjacent an upper end of the shoe portion. The gripping portion will typically be angled relative to the shoe portion. It is particularly preferred that the angle used is at least 900 or more preferably, obtuse although the angle can be less than 900 if desired provided that it is able to be gripped. [0044] The gripping portion will also preferably function as a locating portion, acting to prevent the transition shoe falling between the pole and the ground sleeve. [0045] The transition shoe will preferably be attached to the ground sleeve using an appropriate method so that the transition shoe is not accidentally separated or lost when the pole is removed for replacement or repair. One simple manner of attaching the transition shoe to the ground sleeve is the provision of an opening in the transition shoe, typically in the gripping portion in order to attach a chain, string or similar elongate member or mechanism which is attached to the ground sleeve. [0046] Typically, the transition shoe may be attached to any part of the ground sleeve but the preferred method is the provision of a light chain or similar having one or more links which can be located about or relative to a fastener used to fix the position of the pole relative to the ground sleeve. In this way, the fastener can extend through the opening in one of the links and abut the typically enlarged head of the fastener, preventing removal of the link from the fastener while the fastener engaged with the pole. [0047] The shoe portion of the transition shoe will typically be an elongate, substantially planar portion. The lower end of the shoe portion will typically be tapered to allow easier insertion between the pole and the ground sleeve. The tapered portion can be arcuate when viewed from the side. Typically, the tapered portion will have a concave surface oriented toward the pole. [0048] Preferably, one or more ribs extend longitudinally over the length (or height) of the shoe portion of the transition shoe. Typically, a pair of ribs will be provided extending from adjacent to the gripping portion downwardly to the lower end of the shoe portion. Typically, the ribs will be arcuate in cross-section in order to provide strength to the shoe portion. [0049] The shoe portion may be waveform in shape when viewed from above. The waveform shape can be provided by the ribs or simply that the shoe portion is shaped in that way. [0050] Preferably, the waveform shape is provided such that at least one concave face is oriented toward the pole when the transition shoe is properly inserted. [0051] The assembly of the present invention is preferably provided with a pole restraint device in order to hold a portion of the pole, typically a lower portion of the pole to the sleeve top after the pole has been separated from the sleeve. [0052] In use, the frangible pole of the present invention is designed tear and breakaway at the sleeve top upon impact and in some instances could become a dangerous missile. Using the restraint device, the separated portion of the pole is held to the sleeve and prevents the impact which breaks the pole, from also turning the separated portion of the pole into a projectile. [0053] The restraint device of the preferred embodiment typically includes a restraint collar which is attached to the ground sleeve. The restraint collar is preferably formed to correspond to the outer shape of the pole. It is particularly preferred that the restraint collar be formed from a portion corresponding in cross-sectional shape to the ground sleeve although this is not essential. It is convenient however to use a portion of ground sleeve extrusion to form the restraint collar. It is preferred that the restraint collar be clamped to the pole, approximately 200mm above the upper periphery of the ground sleeve.

0 [0054] The restraint device also includes an attachment assembly to attach the restraint collar (and thereby the pole) to the ground sleeve. Normally, a coupling assembly is provided. The couple assembly typically is or includes a flexible coupling such as a chain or wire or other elongate flexible coupler. [0055] The preferred embodiment of the coupling assembly is a chain. A heavy duty galvanised chain is preferably attached to the restraint collar and connected to the ground sleeve. [0056] In this preferred configuration, the coupling assembly is attached at one portion to a lower fastener used to fix the pole to the ground sleeve and at another portion to the restraint collar. The length of the coupling assembly can vary depending on the pole diameter. Generally the coupling assembly will be approximately 500mm long to allow sufficient length for the pole to break free from the ground sleeve before being pulled to the ground, allowing the vehicle to pass safely over. [0057] The restraint device is easy to fit with the restraint collar mounted to the pole before the pole is placed in the ground sleeve. Once the pole is properly inserted and fixed relative to the ground sleeve, the restraint collar can be fixed relative to the pole. [0058] Normally, the restraint collar will be fixed to the pole in the same method as the pole is fixed to the ground sleeve, namely using a fastener to fix the coupling assembly to the restraint collar and also to fix the restraint collar to the pole. As the preferred restraint collar also includes the preferred U-shaped mounting portion, at least one fastener is used to attach the coupling assembly to the restraint collar and the restraint collar to the pole. The fastener usually includes an enlarged head which prevents removal of the coupling assembly from the ground sleeve or from the restraint collar. [0059] To ensure the breakaway process remains consistent, it is preferred that the pole be provided with a point of weakness. Preferably, the point of weakness is provided or created at the time of installation to prevent unintended breakage of the pole during transport or during installation. It is particularly preferred that an opening is formed in the pole after the pole has been inserted into the sleeve and fixed there using the fasteners. [0060] The opening will preferably be sized according to the dimensions of the pole. For a 100mm pole, a 10mm hole is preferred. As mentioned above, the hole will normally be drilled on site through the pole. The hole is preferably provided above the upper edge of the sleeve into which the pole is inserted. Preferably, the hole is formed approximately 15mm above the sleeve top edge. [0061] Further, the opening will normally be formed in the side of the pole, above the fasteners or locking bolts in the sleeve. This side of the pole and sleeve are preferably installed facing the oncoming traffic when the assembly is used in a traffic sign application. In order to prevent or minimise water, pest or detritus ingress, the hole should also be plugged. Normally the plug will be manufactured of a resilient material and will be deformed during insertion with the resilience of the plug preferably sealing the hole that has been formed. [0062] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention. [0063] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge. BRIEF DESCRIPTION OF DRAWINGS [0064] Various embodiments of the invention will be described with reference to the following drawings, in which: [0065] Figure 1 is an isometric illustration of a frangible pole assembly with transition shoe according to a preferred embodiment of the present invention. [0066] Figure 4 is an axonometric view of the frangible pole assembly illustrated in Figure 1. [0067] Figure 5 is a view from the side of the frangible pole assembly illustrated in Figures 1 and 4 with the transition shoe not fully inserted. [0068] Figure 6 is a view from the side of the frangible pole assembly illustrated in Figures 1 and 4. [0069] Figure 6A is a detailed view of the engagement between the ground sleeve, pole and transition shoe according to a preferred embodiment of the present invention. [0070] Figure 7 is a front view of a transition shoe for use in a frangible pole assembly of a preferred embodiment. [0071] Figure 8 is a side view of the transition shoe illustrated in Figure 7.

IV1~ [0072] Figure 9 is a top view of the transition shoe illustrated in Figures 7 and 8. [0073] Figure 10 is an axonometric view of the components of the restraint device for a frangible pole according to a preferred embodiment of the present invention with the chain connected. [0074] Figure 11 is axonometric view of the components illustrated in Figure 10 with the chain disconnected. [0075] Figure 12 is an axonometric view of a frangible pole with restraint device and transition shoe of a preferred embodiment of the present invention. DESCRIPTION OF EMBODIMENTS [0076] According to a particularly preferred embodiment of the present invention, a frangible pole assembly is provided. [0077] Referring to the illustrations and initially to Figure 1, there is illustrated a frangible pole assembly which comprises a pole 10 and a ground sleeve 11. It should be appreciated that in the illustrations, the length of the pole 10 and the length of the ground sleeve 11 have been shortened. Typically, pole 10 will have a length of anywhere between 1-6 metres and ground sleeve 11 will have a length of anywhere between 20-100 centimetres. [0078] Pole 10 is made of extruded aluminium and particularly of 6261 T5 or T6 aluminium, a high strength, marine grade alloy with a typical yield strength of 275MPa. [0079] The illustrated pole is cylindrical and hollow and has a wall thickness of between 3.75-5.5 millimetres depending on the length of the pole and the use of the pole. [0080] The pole contains a circumferential array of flutes 12 in the outside of the pole. The flutes (see also Figure 3) comprise longitudinal channels extending into the outer face of the pole which define raised portions between the flutes. The flutes extend entirely along the length of the pole and have a width of between 2-5 millimetres and a depth of between 1-4 millimetres. The flutes are somewhat rectangular when viewed in plan, but their cross-sectional shape is not limiting in any way. [0081] The ground sleeve 11 is generally cylindrical and hollow and has a wall thickness of between 3-10 millimetres. The internal diameter of ground sleeve 11 is slightly larger than the external diameter of the pole such that the pole can be positioned within the ground sleeve.

1 1 [0082] The ground sleeve contains a thickened portion 13 or shaped portion to support a pair of threaded fasteners or bolts 14 that is used to fix pole 10 in place once the pole has been positioned within the ground sleeve. [0083] In use, the ground sleeve is concreted or otherwise fixed into the ground surface with approximately 10 centimetres projecting above the ground. [0084] To prevent pole 10 from rotating within the ground sleeve, the ground sleeve is provided with two inwardly extending longitudinal beads 15 (see Figure 2) which extend into the flutes of pole 10 when the pole sits within sleeve 11. [0085] The transition shoe 17 of the preferred embodiment is located adjacent to an upper end of the thickened portion 13 which according to the illustrated embodiments, has a U-shaped channel or recess 20 therein, between the thickened portion 13 and the exterior surface of the pole 10. It can be seen that the transition shoe 17 is located between an inner end of the bolts 14 and the pole 10. [0086] The inner end of the bolts 14 abut the transition shoe 17 which in turn abuts the pole 10 in order to fix the pole in position by applying a clamping force. This also has the effect of spreading the load applied by the bolts 14 over a greater area of the pole 10. [0087] The transition shoe of the preferred embodiment is best illustrated in Figures 7 to 9 and includes a substantially planar shoe portion 22 for insertion between the thickened portion 13 of the ground sleeve 11 and the pole 10. [0088] The transition shoe 17 also includes a gripping portion 21 at or adjacent an upper end of the shoe portion 22. The gripping portion 21 is angled relative to the shoe portion 22 at an obtuse angle. [0089] As a function of the angle of the gripping portion 21, it will also function as a locating portion, acting to prevent the transition shoe 17 falling between the pole 10 and the ground sleeve 11. [0090] The transition shoe 17 of the illustrated embodiment is attached to the ground sleeve 11 using an appropriate method so that the transition shoe is not accidentally separated or lost when the pole 10 is removed for replacement or repair. The particular method used in the illustrated embodiment is the provision of an opening 23 in the transition shoe in the gripping portion in order to attach a chain 18 which is attached to the ground sleeve 11.

I /_ [0091] The transition shoe 17 can be attached to any part of the ground sleeve 11 but the preferred method is the provision of a light chain 18 having one or more links which can be located about a bolt 14 used to fix the position of the pole 10 relative to the ground sleeve 11. [0092] As illustrated in Figures 7 and 8 in particular, the shoe portion 22 of the transition shoe 17 is an elongate, substantially planar portion. The lower end of the shoe portion 22 is tapered to allow easier insertion between the pole 10 and the ground sleeve 11. The tapered portion is arcuate when viewed from the side as seen in Figure 8 with a concave surface oriented toward the pole 10. [0093] A pair of ribs 24 extend longitudinally over the length (or height) of the shoe portion 22 of the transition shoe 17 extending from adjacent to the gripping portion 21 downwardly to the lower end of the shoe portion 22. The ribs illustrated in Figures 7 to 9 are arcuate in cross section in order to provide strength to the shoe portion 22. [0094] The shoe portion is therefore waveform in shape when viewed from above. [0095] In practice, the arrangement of the flutes on the pole is such that should the pole be struck, it will shear at the upper edge 16 of ground sleeve 11 and will break away. The shearing action is contributed to by the flutes 12 and also by the type of metal from which the pole 10 is made. [0096] Figures 10 to 12 show the frangible pole assembly provided with a pole restraint assembly in order to hold a portion of the pole, typically a lower portion of the pole to the sleeve top after the pole has been separated from the sleeve. [0097] The restraint assembly of the preferred embodiment illustrated in Figures 10 and 11 in particular includes a restraint collar 25 which is attached to the ground sleeve 11. The restraint collar 25 is corresponds to the outer shape of the pole 10. A particularly preferred embodiment of the restraint collar 25 is formed from a portion corresponding in cross-sectional shape to the ground sleeve 11 as illustrated. [0098] The restraint assembly of the preferred embodiment also includes a heavy duty galvanised attachment chain 26 to attach the restraint collar 25 (and thereby the pole 10) to the ground sleeve 11. [0099] In this preferred configuration, the chain 26 is attached at one end to a fastener 14 used to fix the pole 10 to the ground sleeve 11 (as illustrated in Figure 12) and at the other end to the restraint collar 25. The length of the chain 26 can vary depending on the pole diameter, but generally the chain will be approximately 500mm long to allow sufficient length for the pole 10 to break free from the ground sleeve 11 before being pulled to the ground, allowing a vehicle to pass safely over. [00100] The restraint assembly is easy to fit with the restraint collar 25 mounted to the pole 10 before the pole 10 is placed in the ground sleeve 11. Once the pole 10 is properly inserted and fixed relative to the ground sleeve 11, the restraint collar 25 can be fixed relative to the pole 10. [00101] Normally, the restraint collar 25 is fixed to the pole 10 in the same method as the pole 10 is fixed to the ground sleeve 11, namely using a fastener 14 to fix the chain 26 to the restraint collar 25 and also to fix the restraint collar 25 to the pole 10. As the preferred restraint collar 25 illustrated in Figures 10 to 12 also includes the preferred U-shaped mounting portion 13, at least one fastener 14 is used to attach the chain 26 to the restraint collar 25 and the restraint collar 25 to the pole 10. The fastener 14 includes an enlarged head which prevents removal of the chain 26 from the ground sleeve 11 or from the restraint collar 25. [00102] The fasteners of the embodiment illustrated in Figures 10 to 12 are all locking bolts with a trilobular tool receiving opening in the enlarged head and are tightened to between 10 - 12 Nm. [00103] It is preferred that the restraint collar 25 be clamped to the pole 10, approximately 200mm above the upper periphery of the ground sleeve 11 as illustrated in Figure 12. [00104] To ensure the breakaway process remains consistent, the pole is provided with a point of weakness, preferably, created during installation to prevent unintended breakage of the pole during transport or during installation. It is particularly preferred that an opening is formed in the pole 10 after the pole 10 has been inserted into the ground sleeve 11 and fixed there using the fasteners 14. [00105] The opening or hole will normally be drilled through the pole 10 on site, preferably, approximately 15mm above the sleeve top edge. [00106] Further, the opening is normally formed in the side of the pole 10, above the fasteners 14 or locking bolts in the sleeve 11. This side of the pole 10 and sleeve 11 are preferably installed facing the oncoming traffic when the assembly is used in a traffic sign application. In order to prevent or minimise water, pest or detritus ingress, the opening should also be plugged. Normally the plug 27 is manufactured of a resilient material and will be I -t deformed during insertion with the resilience of the plug preferably sealing the hole that has been formed. In the illustrated embodiments, a 12mm plug is used for a 10mm hole. [00107] In the present specification and claims (if any), the word 'comprising' and its derivatives including 'comprises' and 'comprise' include each of the stated integers but does not exclude the inclusion of one or more further integers. [00108] Reference throughout this specification to 'one embodiment' or 'an embodiment' means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases 'in one embodiment' or 'in an embodiment' in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations. [00109] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims (5)

1. A frangible pole assembly, the assembly comprising a ground sleeve that is at least partially inserted into the ground, a pole that can slide at least partially within the ground sleeve to hold the pole in place, the pole being provided with circumferential longitudinal flutes at least in the region where the pole contacts an upper edge of the ground sleeve and a restraint assembly to attach the pole to the ground sleeve to prevent separation of the pole from the ground sleeve after the pole has broken.

2. A frangible pole assembly as claimed in claim 1 wherein the ground sleeve is provided with one or more fasteners to fix the pole relative to the ground sleeve.

3. A frangible pole assembly as claimed in either one of the preceding claims wherein the restraint assembly includes a restraint collar attached to the pole and an elongate coupling to attach the restraint collar to the ground sleeve.

4. A frangible pole assembly as claimed in claim 3 wherein the elongate coupling is a chain or cable.

5. A frangible pole assembly as claimed in either one of claims 3 or 4 wherein the restraint collar corresponds in cross-section shape to the ground sleeve.