FIELD OF THE INVENTION

[0001 ] The present invention relates to a method and system for reinforcing an in-ground utility pole having a region of corrosion. As the invention is particularly suited for reinforcing an in-ground utility pole in the form of a frangible classified street light pole, it will be convenient to primarily describe the invention with reference to this particular type of pole. It should however be understood that the invention can also be applied to other forms of utility poles which are mounted in an upright position directly into the ground.

BACKGROUND TO THE INVENTION

[0002] The term "utility pole" as used herein refers to an upright pole or post which is used to support a street light, an overhead power line, a

telecommunications line, a road sign or the like.

[0003] Utility poles are usually made of wood, concrete, steel or fibreglass. Utility poles in the form of street light poles are generally installed on a roadside in close proximity to travelling vehicles in order to provide sufficient illumination of the road surface. Accordingly, street light poles are often in locations where, in the event of an accident, they may be impacted by out of control vehicles. Street light poles are typically hollow, of circular or octagonal transverse cross-section and constructed of relatively thin metal. In this respect, the metal is usually only about 3 mm thick as the poles are designed to be frangible and deform

progressively upon vehicle impact. A frangible street light pole is a safety requirement of most road and traffic authorities. Such authorities are usually responsible for stipulating the requirements to be met for a street light pole to attain a frangible classification. [0004] A problem with frangible street light poles is that their relatively thin metal construction for frangible classification does not allow for significant galvanisation and therefore contributes to premature pole failure. In this respect, over a period of years moisture typically penetrates and corrodes the pole. The corrosion usually occurs near the surface of the ground or below ground level. Over time the corrosion degrades the strength of the pole rendering the pole unsafe and ineffective in withstanding high loads.

[0005] When corrosion occurs, it is necessary to either replace the pole if the corrosion is substantial or attempt to repair the pole to good working condition. In the past, attempts have been made to stabilise/repair corroded street light poles by embedding into the surrounding ground a reinforcement nail on opposite sides of the pole. A reinforcement nail is a form of elongate member, usually of galvanised metal construction, which is placed in abutment with an outer surface of the street light pole.

[0006] Known reinforcement nails are generally designed to be only a temporary solution for street light poles at risk of failure when there are no resources available to replace the pole within a suitable timeframe. Nails at opposing sides of the pole are at least partly driven approximately 700mm into the ground at the base of the pole and then secured to one another with some form of metal strap band which extends around the pole and nails to maintain the nails in abutment with the pole. This generally requires the nails to extend approximately 750mm above ground so that the metal strap band is able to lever, if necessary, the length of the nails into abutment with the pole as the strap is tightened. A problem with this type of nail and fastening arrangement is that the repaired pole can usually no longer be classified as frangible. Further, the metal strap may not be able to prevent the nails from sliding with respect to the pole in the event of an impact.

[0007] It would be desirable to provide a system for supporting an in-ground utility pole and an associated installation method which allows a corroded pole to be reinstated cost effectively and allows the pole to remain classified as frangible. [0008] Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material formed part of the prior art base or the common general knowledge in the relevant art on or before the priority date of the claims herein.

SUMMARY OF THE INVENTION

[0009] In accordance with a first aspect of the invention, there is provided a system for supporting an in-ground utility pole having a region of corrosion at or below ground level, the system including at least one reinforcement nail and a plurality of blind fasteners, the reinforcement nail including an elongate main body for abutting an outer wall of the pole, the main body including an upper section and a lower section with each section having at least one aperture therein, the upper and lower sections being, in use, secured to the pole above and below the region of corrosion, respectively, by said blind fasteners passing through the apertures and into the pole, such that the nail bridges across the region of corrosion to thereby reinforce the pole.

[0010] The utility pole is preferably a frangible street light pole which is hollow and of thin-wall construction. The outer wall of the pole and the reinforcement nail are preferably forced together by said blind fasteners passing through the apertures and into corresponding mounting holes in the outer wall of the pole.

[001 1 ] In one embodiment, the upper and lower sections each include a plurality of apertures for the blind fasteners to secure the nail to the pole. In this regard, the apertures in the upper and lower sections are preferably arranged in one or more rows perpendicular to a longitudinal axis of the main body.

[0012] In an embodiment, at least a rear face of the main body is V-shaped in transverse cross-section to conform with a corresponding V-shape of the outer wall of the pole. In a more preferred embodiment, the pole is octangular in transverse cross-section with the outer wall of the pole having eight side walls, and the entire main body of the reinforcement nail is V-shaped in transverse cross-section. The V-shaped main body conforming with two side walls of the pole.

[0013] The one or more rows in the upper and lower sections of the nail preferably extend from one side of the V-shaped main body across to the other side of the V-shaped main body. The sides of the V-shaped main body are preferably angled at approximately 135° with respect to one another. This angle conforms the V-shaped main body with the angle between adjacent side walls of a pole which is octangular in transverse cross-section.

[0014] In a particularly preferred embodiment, at least one aperture from each row is provided on one side of the V-shaped main body and at least one further aperture from each row is provided on the other side of the V-shaped main body. Preferably, the apertures are approximately 12.5mm in diameter to accommodate high strength blind fasteners made of steel.

[0015] Preferably, each nail is approximately 750 mm in length and in use, no more than approximately 250 mm of the nail is above ground level. This advantageously assists the reinforced pole to remain classified as frangible.

[0016] The apertures in the upper section are preferably spaced at least 100 mm from the apertures in the lower section of the nail. Further, in use, the apertures in the upper section are preferably at least approximately 50 mm above the region of corrosion and the apertures in the lower section are preferably at least approximately 50 mm below the region of corrosion. This advantageously ensures that the securing of the nail to the pole is in regions which are not impacted by corrosion.

[0017] In one embodiment the reinforcement nail preferably includes a projecting shoulder for engagement by a driving tool to drive the nail into the ground. The projecting shoulder preferably extends outwardly from the main body.

[0018] The nails preferably have a thickness of approximately 6mm and the blind fasteners are preferably rivets.

[0019] In another aspect of the invention, there is provided a method of reinforcing an in-ground utility pole having a region of corrosion at or below ground level, the method including the steps of:

- excavating around the pole to a predetermined below ground level;

- providing a plurality of blind fasteners;

- providing a first reinforcement nail having an elongate main body, the main body including an upper section and a lower section with each section having at least one aperture therein for a fastener;

- positioning the elongate main body of the first reinforcement nail in abutment with an outer surface of the pole such that at least one aperture in the lower section of the main body is below the region of corrosion;

- securing a blind fastener into the pole through an aperture in the upper section; and

- securing another blind fastener into the pole through an aperture in the lower section, thereby securing the first reinforcement nail to the pole such that the nail bridges across the region of corrosion to reinforce the pole.

[0020] Preferably, the predetermined depth is approximately 500mm and the step of positioning the reinforcement nail in abutment with the outer wall of the pole includes positioning the nail such that at least one of the apertures in the upper section is at least approximately 50 mm above the region of corrosion and at least one of the apertures in the lower section is at least 50 mm below the region of corrosion. This advantageously ensures that the securing of the nail to the pole is in regions which are not impacted by corrosion. [0021 ] The upper and lower sections may each include a plurality of apertures arranged in one or more rows perpendicular to a longitudinal axis of the main body. Further, the at least one aperture in the upper section which is at least approximately 50mm above the region of corrosion is preferably in a row closest to the region of corrosion. The method may include the further step of securing a blind fastener into the pole through said at least one aperture in said row of the upper section closest to the region of corrosion.

[0022] Preferably, the at least one aperture in the lower section which is at least approximately 50mm below the region of corrosion is in a row of the lower section which is closest to the region of corrosion. In addition, the method may include the further step of securing a blind fastener into the pole through said at least one aperture in said row of the lower section closest to the region of corrosion.

[0023] Depending upon the extent of the corrosion, there may be some instances where the at least one aperture in the lower section which is at least approximately 50mm below the region of corrosion, is in a second or subsequent row of the lower section away from the region of corrosion. In addition, the method may include the further step of securing a blind fastener into the pole through said at least one aperture in said second or subsequent row of the lower section.

[0024] Preferably, after the step of positioning the nail in abutment with the pole, the method includes the further step of drilling mounting holes in the outer wall of the pole where one or more of the apertures in the nail overlie the pole.

[0025] The apertures in the upper section are preferably spaced at least 100 mm from the apertures in the lower section, and the apertures are preferably approximately 12.5 mm in diameter. [0026] The step of positioning the reinforcement nail in abutment with the outer surface of the pole includes positioning the nail such that no more than approximately 250 mm of the nail is above ground level. This advantageously assists the pole to remain classified as frangible.

[0027] The method may further include the steps of:

- providing a second reinforcement nail having an elongate main body, the main body including an upper section and a lower section with each section having at least one aperture therein for a blind fastener;

- positioning the elongate main body of the second reinforcement nail in abutment with the outer wall of the pole at an opposite side of the pole to the first

reinforcement nail such that at least one aperture in the lower section of the second reinforcement nail is below the region of corrosion;

- securing a blind fastener into the pole through an aperture in the upper section of the second reinforcement nail; and

- securing another blind fastener into the pole through an aperture in the lower section of the second reinforcement nail, thereby securing the second

reinforcement nail to the pole such that the second reinforcement nail bridges across the region of corrosion to reinforce the pole.

[0028] The method may further include the step of clamping the first and second reinforcement nails together prior to securing the nails to the pole with said blind fasteners.

[0029] To assist the further understanding of the invention, reference will now be made to the accompanying drawings which illustrate preferred embodiments. It is to be appreciated that these embodiments are given by way of illustration only and the invention is not to be limited by this illustration. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 shows a cross-sectional view of two reinforcement nails of a first type secured to an in-ground utility pole in accordance with an embodiment of the invention.

[0031 ] Figure 2 is a transverse cross-sectional view of the two reinforcement nails and utility pole shown in Figure 1 .

[0032] Figure 3 is a perspective view of a first type of reinforcement nail in accordance with an embodiment of the invention, which is particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole has a width of approximately 75mm.

[0033] Figure 4 is a perspective view of another first type of reinforcement nail which is particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole has a width of approximately 1 15mm.

[0034] Figure 5 is a front view of another first type of reinforcement nail which is particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole has a width of approximately 135mm.

[0035] Figure 6 shows a cross-sectional view of two reinforcement nails of a second type secured to an in-ground utility pole, the reinforcement nails of the second type each having a projecting shoulder extending along a spine of the nail, in accordance with an embodiment of the invention.

[0036] Figure 7 is a transverse cross-sectional view of the two reinforcement nails and utility pole shown in Figure 6. [0037] Figure 8 is a front view of a reinforcement nail of the second type which is particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole has a width of approximately 75mm.

[0038] Figure 9 is a front view of a reinforcement nail the second type which is particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole has a width of approximately 1 15mm.

[0039] Figure 10 is a front view of a reinforcement nail of the second type which is particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole has a width of approximately 135mm.

[0040] Figure 1 1 is a side view of the reinforcement nails of the second type illustrated in Figures 8-10 of the accompanying drawings.

[0041 ] Figure 12 is a perspective view of a blind fastener in the form of a rivet used to secure the reinforcement nails to the pole, in accordance with an embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0042] With reference to the accompanying drawings, there is shown a system for supporting an in-ground utility pole having a region of corrosion at or below ground. The in-ground utility pole may be a street light pole 1 having a region of corrosion 2 at ground level. The pole 1 is of the type which is typically installed by drilling a hole in the ground, inserting an end/base of the pole 1 , backfilling around the base, and compacting the ground to retain the pole 1 in an upright vertical position. The pole 1 is adequately supported when new by the base of the pole 1 extending a sufficient distance below ground level. However, as the pole 1 is normally constructed of a metal such as steel, the base of the pole 1 is prone to corrosion which in some instances leads to significant structural weakening. The pole 1 illustrated in Figures 1 , 2, 6 and 7 is octagonal in transverse cross-section, and the system and method for supporting the pole 1 will be described with reference to a pole 1 of this cross-sectional profile. The system and method of the present invention may however be adapted to suit poles of other cross-sectional profile such as heptagonal, hexagonal, pentagonal, circular, square or triangular.

[0043] The system of the present invention includes at least one

reinforcement nail 3 for supporting an in-ground pole 1 . The nail 3 includes an elongate main body 5 for abutting an outer wall of the pole 1 . The main body includes an upper section 6, which is normally above ground when the nail 3 is installed, and a lower section 8 which is normally below ground level when the nail 3 is installed. The upper and lower sections 6, 8 each have at least one aperture 7, preferably a multiple number of pre-drilled apertures 7 therein.

[0044] The system of the present invention further includes a plurality of blind fasteners which are each preferably in the form of a rivet 4, for example a high strength stainless steel MAGNA-LOK® rivet 4 as illustrated in Figure 12. The nail 3 can be mounted to the pole 1 by securing a rivet 4 into the pole 1 through an aperture 7 in the upper section 6 and securing at least one other rivet 4 into the pole 1 through an aperture 7 in the lower section 8 of the nail 3. In this regard, the upper and lower sections 6, 8 are, in use, secured to the pole 1 above and below the region of corrosion 2, respectively, such that the nail 3 bridges across the region of corrosion 2 to reinforce the pole 1 .

[0045] In Figures 1 and 2, the pole 1 is shown with two nails 3 of a first type secured to the outer surface of the pole 1 at opposite sides. Similarly, in Figures 6 and 7, the pole 1 is shown with two nails 3 of a second type secured to opposite sides of the pole 1 . The opposing arrangement is the preferred approach for reinforcing the pole 1 . Additional nails 3 may be positioned around the pole 1 if required. The main difference between the two types of nails 3 is that the second type is specifically designed to be driven into the ground. In this regard, as shown in Figure 1 1 the second type of nail 3 has a projecting shoulder 13 which extends outwardly from the main body 5 of the nail 3. The projecting shoulder 13 of reinforcement nail 3 can be engaged with a driving tool, for example a jack hammer, during installation to drive the nail 3.

[0046] A cross-sectional view of the pole 1 with reinforcement nails 3 of the first type on opposing sides, and of the second type on opposing sides, is shown in Figures 2 and 7, respectively. Like reference numerals are used in the drawings to identify the same features of both nail types. The main body 5 of nail 3 has a rear face in abutment with the outer wall of the pole 1 . In this respect, the main body 5 of both nails 3 is V-shaped in transverse cross-section with one half of the main body 5 being angled with respect to the other half about a centrally located longitudinal axis. However, in other embodiments, only the rear face of the main body 5 may be shaped to conform with the outer surface of the pole 1 with a front face of the main body being shaped differently. The pole 1 illustrated in Figures 1 , 2, 6 and 7 is octagonal is transverse cross-section and the main body 5 of each nail 3 conforms with two side faces of the pole 1 . In this regard, one half or side of the V-shaped main body 5 is preferably angled at 135° with respect to the other half or side which is consistent with the angle between adjacent side faces of the pole 1 shown. The angle between the two halves of the V-shaped main body 5 may in other embodiments be greater or less than 135° to conform with the particular transverse cross-sectional profile of the pole 1 . In addition, each half of the V-shaped main body 5 preferably has a width which substantially corresponds to the width of the side face of the pole 1 . Further, nails 3 used on poles 1 which are circular in transverse cross-section preferably have a main body 5 which is arcuate to conform with the surface of the pole 1 .

[0047] Figures 3, 4 and 5 illustrate embodiments of the first type of

reinforcement nail 3 and Figures 8 to 1 1 illustrate embodiments of the second type of reinforcement nail 3. The main difference between the two types of nails 3 is that the second type is longer at approximately 950mm and specifically designed to be driven into the ground.

[0048] The first type of nails 3 illustrated in Figures 3, 4 and 5, are each of different size and are particularly suited for utility poles of octagonal transverse cross-section where each side face of the pole 1 has a width of approximately 75mm, 1 15mm and 135mm, respectively. Likewise, nails 3 of the second type illustrated in Figures 8, 9 and 10, are each of different size and suited for utility poles 1 having side faces with a width of approximately 75mm, 1 15mm and 135mm, respectively. The apertures 7 in the nails 3 are ideally arranged in a series of rows perpendicular to a longitudinal axis of the main body 5. The first type of reinforcement nails 3 illustrated in Figures 3 and 5 have two rows of apertures 7 provided in the upper section 6. In contrast, the first type of nail 3 illustrated in Figure 4 has three rows of apertures 7 in the upper section 6. All three of the reinforcement nails 3 have four rows of apertures 7 in the lower section 8 of the nail 3. The top row of apertures 7 in the lower section 8 is sufficient for most applications with the three lowest row of apertures 7 being required if the corrosion zone of the pole 1 extends a greater than normal distance, for example greater than 100mm in length longitudinally of the pole. Likewise, the number of apertures in each row of the second type of nails 3 may vary depending upon the size of the nail 3 with larger nails 3 generally having more apertures 7. In both nail 3 types, the rows preferably extend across both halves of the V-shaped main body 5 with a space provided between the upper and lower sections 6, 8 to bridge across the corroded region.

[0049] The reinforcement nails 3 illustrated in Figures 3 and 8 are the smallest versions of both nail 3 types and are designed for use on 6.5m and 7.0m steel street light poles. The reinforcement nails 3 illustrated in Figures 4 and 9 are intermediate sized nails 3 designed for 10.5m steel street light poles. These nails 3 are significantly wider than the smaller versions illustrated in Figures 3 and 8 as taller street light poles generally have wider side faces. These nails 3 may also have in some instances more apertures 7 than the smaller versions illustrated in Figures 3 and 8. The nails 3 illustrated in Figures 5 and 10 are the largest versions and are designed for 12.5m steel street light poles and have twenty four fastening apertures 7. The apertures 7 in nails 3 of the first type are preferably approximately 12.5 mm in diameter which is substantially the same diameter as the preferred stainless steel high strength rivets 4. In contrast, the apertures 7 in nails 3 of the second type are slightly smaller with a diameter of approximately 10 mm and subsequently require rivets 4 of a smaller diameter. The reinforcement nails 3 are preferably made from 6 mm thick, 350 mPA grade steel which is galvanised in accordance with AS/NZS 4680:2006.

[0050] The reinforcement nails 3 of the first type illustrated in Figures 3, 4 and 5 are approximately 750 mm in length. When the reinforcement nails 3 are installed on a pole 1 , the majority of the nail 3 is below ground with preferably no more than approximately 250 mm of the nail 3 above ground level. This ensures that in the event of the pole 1 being impacted by a motor vehicle in an accident, the majority of the vehicle impact with the pole 1 will be above the nail 3. This advantageously assists the pole 1 to maintain a frangible classification which is particularly important for safety. The apertures 7 in the upper section 6 of the nail 3 are preferably spaced at least approximately 200 mm from the apertures 7 in the lower section 8. It is in the region between the upper and lower sections 6, 8 that the corroded region of the pole 1 is ideally positioned.

[0051 ] The method of installing a nail 3 on a corroded pole 1 includes the initial step of checking the pole 1 location and identification number to ensure that it is the correct pole 1 requiring repair with a nail 3. A visual inspection may then be conducted of the top region of the pole 1 to confirm that it can be repaired safely. A further visual inspection of the pole 1 at ground level may be

undertaken to assess whether the pole 1 requires temporary support during the repair/reinstatement process.

[0052] In preparation for the installation of the nail 3, the ground soil immediately surrounding the pole 1 is preferably excavated to a depth of approximately 500 mm and a check of the condition of the pole 1 below ground undertaken. A pole 1 is generally considered to be repairable if the region of corrosion in or around the pole 1 is approximately 245 mm or less (excluding surface rust) in length longitudinally of the pole 1 . As street light poles, typically have a cable entry slot at or near the base of the pole for electrical cable, it is important that the cable entry slot is located such that the nail 3 is not installed against the pole 1 in a position which would impede upon the electrical cable. In this regard, it should be noted that street light poles which are classified by regulatory authorities as being frangible do not usually have overhead pole cabling as the cabling would tend to hold the pole upright in the event of an impact. Frangible street light poles therefore have internal electrical cabling for the light source on top of the pole 1 . The electrical cabling enters the pole 1 via the cable entry slot which is generally located directly below the termination hole and cover plate. The cover plate may need to be removed to check that the cables are not touching the outer wall of the pole 1 and cannot be damaged during drilling of mounting holes in the pole 1 for the nails 3.

[0053] Once the ground soil is excavated and cable entry slot located, a suitably sized reinforcement nail 3 is then selected, taking into consideration the dimensions of the pole 1 . A first nail 3 is then positioned in abutment against the pole 1 and a second nail 3 is preferably positioned in abutment with the pole 1 at an opposite side face of the pole 1 . The nails 3 are then preferably held together with some form of chain, ratchet strap or the like which ensures that the nails 3 remain in close proximity to the pole 1 during the installation process.

[0054] If a nail 3 of the second type is being installed the projecting shoulder 13 may then be engaged with a driving tool, for example a jack hammer, to drive the nail 3 into the ground below the excavated region approximately 200mm further. In this respect, nails 3 of the second type have an overall length of approximately 950mm which is about 200mm longer than nails 3 of the first type. The driving tool is ideally positioned over at least the projecting shoulder 13 of the nail 3 to drive the nail 3 downwardly to the desired predetermined depth.

[0055] The correct depth/location of the reinforcement nail 3 with respect to the pole 1 is a position where the lowest row of apertures 7 in the upper section 6, ie the row of apertures closest to the region of corrosion, is approximately 50 mm above the region of corrosion in the pole 1 . If a bottom edge of the corrosion/rust band overlaps or is within approximately 50 mm of the top row of apertures 7 in the lower section 8, ie the first row of apertures 7, the next (second) or

subsequent row of apertures 7 located approximately 100mm immediately below the first (top) row of apertures 7 may instead be used to secure the nail 3. In this respect, the bottom three rows of apertures 7 in the lower section 8 of the nail 3 are utilised as required if the corrosion zone extends beyond what would generally be regarded as normal, ie if the rust band exceeds approximately 100mm.

[0056] Once both reinforcement nails 3 are correctly positioned against the pole 1 , a drill can be placed in the required apertures 7 such that appropriate mounting holes for the rivets 4 can be drilled in the pole 1 . A rivet gun may then be used to install high strength rivets 4 into each desired aperture 7 of the upper and lower sections 6, 8 and underlying mounting hole 4. Once the rivets 4 have been secured, ground soil can be returned around the base of the pole 1 and compacted if required.

[0057] Blind fasteners such as rivets 4 are used in the installation process for a number of important reasons. Firstly, there is no internal access to the pole apart from the cable entry slot. Accordingly it is extremely difficult if not impossible to fasten the nail 3 and outer wall surface of the pole 1 together using a nut and bolt arrangement. The rivets 4 advantageously allow for the attachment of the nails 3 without having to gain access inside the pole 1 . Secondly, as street light poles which are classified as frangible are usually hollow and of thin-wall construction, securing a nail 3 to the pole 1 with a fastener extending right through to the other side of the pole 1 could crush the walls of the pole 1 .

Securing the nails 3 instead with rivets 4 advantageously avoids this issue.

Further, the use of rivets 4 advantageously eliminates the potential for vandals to easily remove the fasteners and thus prevent the structural integrity of the pole 1 being impacted. In addition, the inherent deformation of the riveting process avoids the potential for loosening, unlike nut and bolt arrangements which are prone to loosening over time due to cyclic loading. Moreover, rivets 4 are robust enough to apply a clamping force to ensure the interface of the nail 3 and pole 1 are in near contact. All components of the system including the reinforcement nails 3 are advantageously manufactured from materials designed for durability within the environment in which the poles 1 are installed. By riveting a reinforcement nail 3 directly to the pole 1 above and below the corroded section, the system of the present invention advantageously provides a load bridge connecting the upper portion of the pole 1 to structurally sound pole 1 below the corroded section.

[0058] Although the preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.