AU2008259380B2

AU2008259380B2 - Loop apparatus and installation method thereof

Info

Publication number: AU2008259380B2
Application number: AU2008259380A
Authority: AU
Inventors: Peter James Gambell
Original assignee: Pjs Loop Service Pty Ltd
Current assignee: PJ'S LOOP SERVICE Pty Ltd
Priority date: 2008-01-11
Filing date: 2008-12-18
Publication date: 2013-08-29
Anticipated expiration: 2028-12-18
Also published as: NZ573771A; AU2008259380A1

Abstract

Abstract Loop Apparatus, and Installation Method Thereof 5 A loop apparatus (400, 500, 700, 800) for detecting a vehicle on a roadway. The loop apparatus (400, 500, 700, 800) comprises an insulated loop of conductive wire for connection with sensor electronics, and a cover layer (430, 530, 730, 830) provided on top of the loop of conductive wire. The cover layer (430, 530, 730, 830) is of a material different to that of the roadway surface (425, 520, 725, 825). -5/7

Description

S&F Ref: 889751 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address PJ's Loop Service Pty Ltd, of Applicant: 118 Weaver Street, Erskine Park, New South Wales, 2759, Australia Actual Inventor(s): Peter James Gambell Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Loop apparatus and installation method thereof Associated Provisional Application Details: [33] Country: [31] Appl'n No(s): [32] Application Date: AU 2008900156 11 Jan 2008 The following statement is a full description of this invention, including the best method of performing it known to me/us: 5845c(1 899510_1) - 1 Loop Apparatus and Installation Method Thereof Technical Field The present invention relates generally to loop detectors, and in particular, to loop detectors used 5 in the detection of vehicles on roadways. Background Loop detectors are commonly used in the detection of vehicles on roadways, such as at traffic signals, car parks, and at automatic gates/boom gates. As shown in Fig. 1, a loop detector 100 0 includes a loop of wire 110 comprising of a number of coils/turns 215 (Fig. 2) installed under the surface of the roadway, and sensor electronics 120 to which the loop of wire 110 is connected. The sensor electronics 120 detects changes in the inductance of the loop of wire 110 caused by the entering and exiting of a body of conductor (such as a vehicle) into and out of the area of the loop of wire 110. 5 A conventional method of installing a loop detector 100, as shown in Fig. 2, involves stripping off a top layer of a roadway 200, laying and connecting the loop of wire 110, and resurfacing the roadway 200 thereafter. An adhesive material 210 is sometimes used to hold the loop of wire 110 in place during the installation process. This method of installation, however, is laborious and D time consuming. This method of installation is also disadvantageous as the loop of wire 110 is left exposed to traffic (construction or otherwise) which may run over the wires. For example, if road works span several days it is not uncommon for regular traffic to be allowed onto the section of roadway being worked on at certain times of the day. Even if regular traffic is not allowed onto the roadway under construction, construction vehicles are still present and allowed 25 to travel over this roadway. Such traffic would cause damage to the wires, and/or cause them to move even if adhered to the ground by the adhesive material 210. Another conventional method of installing a loop detector is as shown in Fig. 3. In this method, a trench 310 is cut into the roadway, and the loop of wire 110 laid into the trenches 310. The 30 trenches 310 are filled in and the roadway resurfaced after the loop of wire 110 is laid. This installation method is commonly used to install a new loop detector 100 into an existing roadway, such as in a roadway where an old loop detector has failed, or in an existing roadway where no loop detector has been previously installed. This method of installation, however, does -2 not remove any existing loops of wire previously installed into the roadway, and instead installs a new loop of wire over, or shifted laterally from, any existing loops of wire. As a rule of thumb, up to a maximum of four loops of wire may be installed one next to another in a standard size lane of a roadway. This means that after four loop detectors have been installed, and subsequently failed, the section of roadway must be stripped and a new loop detector installed according to the above described first conventional method. Further, both the above described conventional installation methods do not provide protection for the loop of wire 110 from common causes of coil malfunction after installation. Common causes of coil malfunction include natural earth movement, and warping of the roadway due to one or a combination of heat and heavy vehicle traffic/braking on the roadway. Such movement causes the roadway and hence the wires installed therein to move, resulting eventually in the breaking of the wires, shorting, and the like. It would be advantageous if loop detectors could be installed in a more reliable and efficient manner. It would further be advantageous if the loop detectors could be installed in such a manner as to be more resilient, and to hence require less frequent re-installation and repair. Summary According to an aspect of the disclosed invention, there is provided a loop apparatus for detecting a vehicle on a roadway, the loop apparatus comprising an insulated loop of conductive wire provided on a surface of the roadway for connecting to sensor electronics, and a cover layer provided on top of the insulated loop of conductive wire, the cover layer being of a material different to that of the roadway surface. The cover layer is mechanically bonded to the surface of the roadway as a result of heating applied to the cover layer. According to another aspect of the disclosed invention, there is provided a method of installing a loop apparatus for detecting vehicles on a roadway. The method comprises the steps of: laying the loop apparatus on a surface of the roadway; and applying heat to cause the loop apparatus to melt and thereby form a mechanical bond with the surface of the roadway. According to another aspect of the invention, there is provided a pre-fabricated loop apparatus comprising a plurality of coils or turns of insulated conducting wire sandwiched '7C1 AEL 1 -3 between sheets of thermoplastic material and heated to cause said thermoplastic material to encapsulate said plurality of coils or turns of insulated conducting wire, wherein said thermoplastic material has a melting temperature lower than that of the insulating material covering the plurality of coils or turns of conductive wire. Brief Description of the Drawings Some aspects of the prior art and one or more aspects of the disclosed invention will now be described with reference to the drawings, in which: Fig. 1 is a plan view of a loop detector. Fig. 2 illustrates a conventional installation of a loop of wire in a loop detector. Fig. 3 illustrates another conventional installation of a loop of wire in a loop detector. Figs. 4A to 4C illustrate a loop apparatus, and an installation thereof, according to an aspect of the disclosed invention. Fig. 5 illustrates a loop apparatus, and an installation thereof, according to another aspect of the disclosed invention. Figs. 6A to 6B illustrate a packaged-coil according to another aspect of the disclosed invention. Figs. 7A to 7C illustrate a loop apparatus, and an installation thereof, according to another aspect of the disclosed invention. Figs. 8A to 8C illustrate a loop apparatus, and an installation thereof, according to another aspect of the disclosed invention. Detailed Description In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and together with which is described by way of illustration one or more exemplary embodiments of the present invention. The following detailed description is not to be taken in a -4 limiting sense. Further embodiments may be utilized, and logical, mechanical, and other changes may be made without departing from the spirit or scope of the present invention. The scope of the present invention is defined only by the appended claims. 5 With reference to Figs. 4A through to 4B, a loop apparatus 400, and an installation thereof, according to a first embodiment is described. The loop apparatus 400 includes a loop of wire for connection with sensor electronics (not shown). The loop of wire comprises a number of insulated coils/turns 415. The coils 415 are laid on a sub-surface 420 beneath the level of a roadway surface 425. The roadway surface 425 may, for example, be stripped to expose the sub 0 surface 420. Alternatively, the coils 415 may be laid on the sub-surface 420 at the time of roadway construction, before the roadway is sealed by the roadway surface 425. As used herein, a roadway includes roads, thoroughfares in and around parking areas, parking bays, vehicle accessible ramps, garage floors, showroom floors, and any surface on which a vehicle may be present. 5 Following the laying of the coils 415 on the sub-surface 420, a thermoplastic material 430 is laid on top of the coils 415. The thermoplastic material 430 is heated, whereby the thermoplastic material 430 melts over the coils 415. Preferably, the thermoplastic material 430 is heated or otherwise adapted to at least partially seep into the sub-surface 420 to form a mechanical bond .o therewith. The thermoplastic material 430 is selected to have a melting temperature lower than that of the insulating material sheathing the coils 415. The thermoplastic material 430 is left to harden, thereby forming a cover layer 430 over the coils 415, as shown in Fig. 4B. The loop of wire, coils 415, and cover layer 430 form a primary portion of the loop apparatus 400. 25 The cover layer 430 provides a function of adhering the coils 415 in place. More importantly, the cover layer protects the coils 415 from damage. For example, in the event that construction of, or on, the roadway extends over a number of days, the roadway can still be opened for public use while minimizing any potential damage to the coils 415 from traffic. Even if the roadway is closed to public use over the construction period, the cover layer 430 provides protection against 30 damage to the coils 415 from construction vehicles such as loaders, trucks, steam rollers and the like.

-5 After the thermoplastic material 430 has hardened, the sub-surface 420 is filled in/sealed, as shown in Fig. 4C with bitumen, aspheric concrete, paving/tiling, or other suitable material 440. The roadway surface 420 may be thereafter flattened in a variety of methods known to those skilled in the art. 5 In addition to the protection offered by the cover layer 430 at the time of construction, the cover layer further assists in extending the life of the coils 415 during operation. The cover layer minimizes the movement of the coils 415 in response to movement or warping of the roadway from ground movement, heat, heavy vehicles, and the like. The frequency of repairs on the o roadway is therefore reduced. At any time after the laying of the coils 415 on the sub-surface 420, the loop apparatus 400 may be connected to the sensor electronics (not shown) to form a loop detector. 5 A loop apparatus 500, and an installation thereof, according to a second embodiment is described with reference to Fig. 5. The loop apparatus 500 includes a loop of wire comprising a number of insulated coils/turns 515. The loop of wire is laid on a roadway surface 520. A thermoplastic material 530 is laid over the coils 515 and melted thereon. The thermoplastic material 530 is chosen to have a lower melting temperature than that of the insulating material sheathing the o coils 515. Preferably, the thermoplastic material 530 is heated and/or otherwise adapted to at least partially seep into the roadway surface 520 to form a mechanical bond therewith. The loop of wire, coils 515, and cover layer 530 form a primary portion of the loop apparatus 500. The loop apparatus 500 according to the second embodiment can be installed without requiring 25 the roadway surface 520 to be stripped off. Installation of the loop apparatus 500 is hence significantly simpler and quicker as compared to the conventional loop detector requiring stripping or trenching of the roadway surface 520. Furthermore, repairs and re-installation of the loop apparatus according to the second embodiment are significant quicker and easier as the malfunctioned loop of wire can be easily removed off of the roadway surface 520 and a new loop 30 of wire installed thereon. A loop apparatus 700, and an installation thereof, according to a third embodiment is described with reference to Figs. 6A to 6B, and 7A to 7C. The loop apparatus 700 according to the third -6 embodiment is partially fabricated off-site. Packaged-coils 600 are pre-fabricated off-site by sandwiching insulated coils 615 between two sheets of thermoplastic material 630, as shown in Fig. 6A. The sheets of thermoplastic material 630 are of similar material and properties to those used in the embodiments described hereinbefore. The sheets of thermoplastic material 630 are of 5 a size suitable for sufficiently encapsulating the insulated coils 615 when melted, and typically are around 75mm in width. It should be understood that this width is exemplary only, and the actual width of the sheets of thermoplastic material 630 are not limited in this manner. The packaged-coils 600 of the present embodiment are shown comprising two insulated coils 615, however it should be understood that any number of insulated coils 615 may be encapsulated. o The insulated coils 615 and thermoplastic material 630 are heated using, for example, a jig to form or fabricate packaged-coils 600. The packaged-coils 600 are transported to the work site for installation. Figs. 7A to 7C illustrate the process of installing the packaged-coils 600. As shown in Fig. 7A, 5 and in a similar manner to the process illustrated in Figs. 4A to 4C, a roadway surface 725 may, for example, be first stripped to expose the sub-surface 720. Alternatively, the insulated coils 615 may be laid on the sub-surface 720 at the time of roadway construction, before the roadway is sealed by the roadway surface 725. Packaged-coils 600 are laid upon the sub-surface 720. o As shown in Fig. 7B, the packaged-coils 600 are heated to cause the thermoplastic material 630 of the packaged-coil 600 to melt. Preferably, the thermoplastic material 630 is heated or otherwise caused to at least partially seep into the sub-surface 720 to form a mechanical bond therewith. In Fig. 7C, after the thermoplastic material 430 has hardened, the sub-surface 720 is filled in/sealed, as shown with bitumen, aspheric concrete, paving/tiling, or other suitable 25 material 740. The roadway surface 720 may be thereafter flattened in a variety of methods known to those skilled in the art. The packaged-coils 600 may be made in a variety of sizes to suit various applications. Typically, the packaged-coils 600 are of width 50mm to 100mm. 30 Fabricating the packaged-coils 600 off site allows for better fabrication efficiency and tighter tolerances. The time spent on site is further reduced, whereby roadway closures and traffic congestion and general inconveniences caused thereby are minimized.

-7 A loop apparatus 800, and an installation thereof, according to a fourth embodiment is described with reference to Figs. 8A to 8C. The installation of the loop apparatus 800 is similar to that for the loop apparatus 400 described hereinbefore, except that thermoplastic material layers 835 and 5 830 are laid under and on top of the insulated coils 815, respectively, as shown in Fig. 8A. The thermoplastic material used in the fourth embodiment is of similar material and properties to those used in the preceding embodiments. The top layer of thermoplastic material 830 forms a cover layer, and the bottom layer of thermoplastic material 835 forms an under-layer. The preceding and subsequent processes of stripping the roadway surface 825, heating the 0 thermoplastic material layers 830 and 835, sealing the roadway surface 825, and so on are otherwise identical to those illustrated in Figs. 4A to 4C. During installation, the under-layer is also heated so as to bond with the cover layer. Preferably, the under-layer is heated to also partially seep into the sub-surface 820 and form a mechanical bond therewith. 5 Providing a further under-layer of thermoplastic material 835 under the insulated coils 815 affords additional protection to the insulated coils 815 during construction, and additional resilience to warping and breakage after construction and during roadway use. The thermoplastic materials or layers 430, 530, 630, 830 used in the above described 0 embodiments may be of the same or similar material used for lane marking. An example of a suitable thermoplastic material is Flexitherm Preform Thermoplastic TM manufactured by Benty Pty Ltd of Lot 15, Saltspray Close, Redhead NSW 2290, comprising of hydrocarbon resins, glass beads, plasticisers, titanium dioxide, and inert extenders, and Quartz/Glass bead aggregate mixes, also manufactured by Benty Pty Ltd, comprising of crystalline silica and soda lime glass. 25 Introduction of the use and installation of the loop apparatuses 400, 500, 700, 800 into current construction workflows, practices, and logistics is hence simplified as new or exotic materials are not required. The insulated coils/turns 415, 515, 615, 815 may be wound in a variety of arrangements, 30 including clockwise, anti-clockwise, figure-8, and the like. Each loop of wire 110 may comprise one or more turns, depending on a required sensitivity.

Claims

1. A loop apparatus for detecting vehicles on a roadway, the loop apparatus comprising: an insulated loop of conductive wire provided on a surface of said roadway for connecting to sensor electronics; and a cover layer provided on top of the insulated loop of conductive wire, the cover layer being of a material different to that of the roadway surface; wherein said cover layer is mechanically bonded to the surface of said roadway as a result of heating applied to said cover layer.

2. A loop apparatus as claimed in claim 1, wherein the loop of conductive wire is provided on a sub-surface beneath a top surface of the roadway.

3. A loop apparatus as claimed in claim 1, wherein the loop of conductive wire is provided on a top surface of the roadway.

4. A loop apparatus as claimed in any one of claims I to 3, wherein the cover layer comprises a thermoplastic material.

5. A loop apparatus as claimed in claim 4, wherein the cover layer is melted over the loop of conductive wire.

6. A loop apparatus as claimed in claim 5, wherein the cover layer has a melting temperature lower than that of the insulating material covering the loop of conductive wire.

7. A loop apparatus as claimed in any one of claims I to 6, wherein the cover layer is adapted to partially seep into the surface on which the loop of conductive wire is provided.

8. A loop apparatus as claimed in any one of claims 1 to 7, wherein the loop of conductive wire comprises a plurality of coils or turns. '7C IA' 7n I -9

9. A loop apparatus as claimed in any one of claims 1 to 7, and further comprising an under-layer provided under the insulated loop of conductive wire, the under-layer being of a material different to that of the roadway surface.

10. A loop apparatus as claimed in claim 9, wherein the under-layer is comprises a thermoplastic material.

11. A loop apparatus as claimed in claim 9, wherein the under-layer is of the same material as the cover layer.

12. A method of installing a loop apparatus for detecting vehicles on a roadway, the method comprising the steps of: laying said loop apparatus on a surface of said roadway; and applying heat to cause said loop apparatus to melt and thereby form a mechanical bond with said surface of said roadway.

13. A method as claimed in claim 12, wherein said step of laying said loop apparatus on a surface of said roadway comprises the sub-steps of: laying a loop of insulated conductive wire on a surface of said roadway; and covering the loop of insulated conductive wire with a cover layer of material different to that of said roadway surface.

14. A method as claimed in claim 12, wherein said loop apparatus is pre fabricated and comprises a loop of insulated conductive wire and a cover layer.

15. A method as claimed in any one of claims 13 to 14, wherein the cover layer comprises a thermoplastic material.

16. A method as claimed in claim 15, wherein the thermoplastic material is heated to a temperature lower than the melting temperature of the insulating material of the loop of insulated conductive wire. '7C IAnVA I -10

17. A method as claimed in any one of claims 15 to 16, wherein the thermoplastic material is heated to a temperature that causes said thermoplastic material to adhere to said surface of said roadway.

18. A method as claimed in any one of claims 15 to 17, comprising the further step of providing an under-layer of thermoplastic material under the loop of insulated conductive wire.

19. A method as claimed in any one of claims 12 to 18, wherein said roadway surface comprises a sub-surface and said method comprises the further step of covering said loop apparatus with roadway surface material.

20. A method as claimed in any one of claims 12 to 19, wherein said loop of insulated conductive wire comprises a plurality of coils or turns of insulated conductive wire.

21. A pre-fabricated loop apparatus comprising a plurality of coils or turns of insulated conducting wire sandwiched between sheets of thermoplastic material and heated to cause said thermoplastic material to encapsulate said plurality of coils or turns of insulated conducting wire, wherein said thermoplastic material has a melting temperature lower than that of the insulating material covering the plurality of coils or turns of conductive wire.

22. A loop apparatus substantially as hereinbefore described with reference to any one of the embodiments, as that embodiment is shown in any one or more of Figs. 4 to 8.

23. A method of installing a loop apparatus, the method substantially as hereinbefore described with reference to any one of the embodiments, as that embodiment is shown in any one or more of Figs. 4 to 8.

24. A pre-fabricated loop apparatus for detecting vehicles on a roadway, the pre fabricated loop apparatus substantially as hereinbefore described with reference to any '7C I A I *1 -Il1 one of the embodiments, as that embodiment is shown in any one or more of Figs. 6 to 7. PJ's Loop Service Pty Ltd Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON