P/00/009A Section 29 AUSTRALIA Patents Act 1990 INNOVATION PATENT SPECIFICATION Invention Title: METHOD AND SYSTEM FOR DETECTING COMPONENT DEGRATDATION IN A TRANSPORT NETWORK Applicant: Monash University The invention is described in the following statement: 1 7019 Method and system for detecting component degradation in a transport network 5 This application claims priority from Australian Provisional Patent Application No 2010903914 filed 31 August 2010 the entire contents of which are to be taken as incorporated herein by reference. 10 Field of the Invention The present invention relates generally to detecting degradation, such as stresses and cracking prior to failure, of components in a transport network. The present invention is suitable for use in the detection of degraded insulated rail joints forming part of a network of railway tracks, and it will be convenient 15 to describe the invention in relation to that exemplary, but non-limiting application. Background of the Invention Insulated rail joints are an integral part of rail networks, as they enable 20 the separation of otherwise electrically continuous rail lengths into discrete electrical sections, which allows train controllers to determine whether a train is present in a particular section, as well as to determine whether a rail has failed. By their nature, insulated rail joints are one of the weakest links in continuously welded rail, and can fail without warning, leading to network disruptions as well 25 as a derailment risk. The insulated rail joint consists of insulating material, typically fibreglass matting, sandwiched between steel joint bars on both sides of the rail. The joint bars are bolted to the rails with insulating bushes to provide the mechanical support without electrical contact. 30 An insulated rail joint can fail either electrically or mechanically. Electrical failure occurs when there is breakdown of the insulation between the rails and joint bars that provides a conductive path. Mechanical failure typically occurs with the initiation and then propagation of a fatigue crack from the highly stressed locations; the most common position for such cracking is 2 922953 the lowest position at the midpoint of the joint bars. Electrical failures are less problematic than mechanical failures, as the electrical contact can indicate a problem via the normal signalling circuits, and in most cases take place after mechanical failures. In contrast, cracking at the joint bars prior to mechanical 5 failure is not detectable via the normal signalling systems, and is not detectable via the ultrasonic track inspection vehicles. The only means for detecting cracks in the joint bars is via close inspection of a given joint, which is impractical on a daily basis. In practice, routine visual inspection of the track will reveal locations where there is insufficient track support and therefore 10 higher loading of the insulated rail joint. However, these inspections rely on the skill and experience of the track inspectors, and there is no backup system that provides an active warning to alert the train controllers or any other authorities independent of the track inspectors. 15 There exists a need to detect the degradation of components in a transport network, such as insulated rail joints, in a manner which is simple, reliable and relatively inexpensive. Moreover, there exists a need to provide method and/or system of a detecting the degradation of components in a transport network, such as insulated rail joints, which ameliorates or 20 overcomes one or more disadvantages or inconveniences of known detection methods and/or systems. Summary of the Invention One aspect of the invention provides a system for detecting degradation 25 of a component in a transport network, including: * a group of one or more measurement devices for measuring an operating property of the component; e at least one RFID tag in communication with the group of measurement devices to capture data indicative of the operating property; 30 e at least one RFID reader for reading the captured data from the RFID tag, wherein one of the RFID tag and the RFID reader is attached to vehicle adapted to travel on the transport network, and the other of the RFID tag and RFID reader is provided at a fixed point on the transport 3 922953 network, to enable reading of the captured data when the vehicle travels on the transport network; and * a data analysis device for identifying degraded components from the captured data. 5 In one or more embodiments, the captured data includes: * one or more operating property measurements from the group of measurement devices. 10 In one or more embodiments, one or more of the measurement devices are strain gauges, crack detection or crack propagation gauges or a combination of these items. In one or more embodiments, each strain gauge, crack detection or crack 15 propagation gauges or a combination of these items is affixed to the component. In one or more embodiments, the operating property measurements are peak strain values or crack growth rates. 20 In one or more embodiments, the data analysis device identifies component degradation: e if the operating property measurements indicate a non-operative state of any of the measurement devices. 25 In one or more embodiments, non-operative state is an open-circuit condition of the strain gauges or crack detection gauges. In one or more embodiments, the data analysis device identifies a high risk 30 of component degradation: * If the operating property measurements vary significantly from previous readings. 4 922953 In one or more embodiments, the RFID tag further stores measurement related data including any one or more of: " an RFID tag identifier; " a time stamp indicating when the operating property measurements 5 were taken; and " error checking data comparing different operating property measurements from a plurality of operating property measurements taken at the same time from the same group of measurement devices. 10 In one or more embodiments, the data analysis device identifies measurement device degradation: * if no data was read from the RFID tag. In one or more embodiments, the data analysis device identifies 15 measurement device degradation: 0 if the operating property measurements and/or the measurement related data indicates that data on the RFID tag was not recently updated due to inactivity or non-operation of the controller in the measurement device. 20 In one or more embodiments, the data analysis device identifies measurement device degradation: * if the operating property measurements and/or the measurement related data indicate that a plurality of operating property measurements 25 taken at the same time from the same group of measurement devices are not comparable. Another aspect of the invention provides a method for detecting degradation of a component in a transport network, including: 30 * measuring an operating property of the component with a group of one or more measurement devices; e capturing data indicative of the operating property in at least one RFID tag in communication with the group of measurement devices; 5 922953 " reading the captured data from the RFID tag with at least one RFID reader, wherein one of the RFID tag and RFID reader is attached to vehicle adapted to travel on the transport network, and the other of the RFID tag and RFID reader is provided at a fixed point on the transport 5 network, to enable reading of the captured data when the vehicle travels on the transport network; and * identifying degraded components from the captured data at a data analysis device. 10 Yet another aspect of the invention provides a system for detecting degradation of a defective insulated rail joint forming part of a rail network, the rail network including a plurality of insulated rail joints, the system including: * a group of one or more strain measurement devices or crack propagation or detection gauges, each group being mounted to a 15 different one of the plurality of insulated rail joints; " a plurality of RFID tags, each tag being in communication with a different group of strain measurement devices to read strain-related data from that group of strain measurement devices; e an RFID reader for reading data from the RFID tags, wherein RFID 20 reader is attached to a rail-mounted vehicle to enable reading of the strain-related data from RFID tags when the rail-mounted vehicle travels over the plurality of insulated rail joints; and " a data analysis device for identifying degraded insulated rail joints from the strain-related data. 25 0 Brief Description of the Drawings In order that the invention may be more clearly ascertained, embodiments will now be described, by way of example only, with reference to 30 the accompanying drawings, in which: Figure 1 is a schematic diagram of one embodiment of a system for detecting degradation of a defective insulated rail joint forming part of a rail network; 6 922953 Figure 2 is a schematic diagram showing the function blocks of the system components depicted in Figure 1; and Figure 3 is a timing diagram showing data capture, data processing and data transmission/reception operations which occur in the various elements 5 depicted in Figure 2. Description of the Drawings Referring now to Figures 1 and 2, there are shown generally a system for detecting degradation of a defective insulated rail joint forming part of a rail 10 network. In this system, two exemplary sections 10 and 12 of rail are supported by three sleepers 14, 16 and 18 on a crushed stone ballast bed 20. The rail section 10 includes an insulated rail joint 22. Mounted to either side of the insulated rail joint 22 are a group of two strain gauges 24 and 26. The strain gauges 24 and 26 each consist of an insulating flexible backing which 15 supports a metallic foil pattern. The strain gauges 24 and 26 are attached to the insulated rail joint 22 by a suitable adhesive, such as cyanoacrylate or can be bonded using a spot welder and weldable type strain gauges. As the insulated rail joint 22 is placed under load by a passing train carriage or other rail-guided vehicle, the foil is deformed, causing its electrical resistance to 20 change. On development of a crack in the insulated rail joint 22, the metallic foil pattern is severed which leads to an open-circuit condition across the relevant strain gauge or crack detection gauge. The resistance change of the strain gauges 24 and 26 is measured by 25 control circuitry 28 to which the strain gauges 24 and 26 are connected. The control circuitry 28 notably includes strain amplifiers 30 and 32 which are respectively adapted to read and amplify the resistance values of the strain gauges 24 and 26, a battery 34 or other power source, and an RFID interface 36. 30 The control circuitry 28 is in communication with an RFID tag 38. The control circuitry 28 and RFID tag 38 are both mounted in a single housing 40 which is affixed to the sleeper 14. The RFID tag 38 notably includes a 7 922953 controller 42 for controlling modulation/demodulation functions, data processing operations and transmission operations, an associated memory 44 for storing data and instructions for the controller 42, and an antenna providing a contactless interface 48 to an RFID reader/interrogator 50. In this example, 5 the RFID tag 38 is an active tag equipped with a battery 46 or other power source that can be used as a partial or complete source of power for the tag's circuitry and antenna. However in other embodiments the tag may be a passive tag which does not contain a battery, the power instead being supplied via inductive coupling with the RFID reader/interrogator 50. 10 The RFID reader/interrogator 50 notably includes an antenna providing a contactless interface 52 to an RFID tag 38, and a data reader including a data modulator/ demodulator 54, a coder/decoder 56 and a control unit 58 for storing and processing information, modulation/demodulation operations and 15 other specialized functions. The RFID reader/interrogator 50 is connected to a data logger 60. The data logger 60 includes a processor 62 for reading and executing program instructions stored in an associated memory 64, notably to view and analyze 20 collected data. The memory 64 also stores data received from the RFID reader/interrogator 50. A battery 66 provides power to the various components of the data logger 60. The data logger 60 optionally includes a data modem 68 and associated antenna 70 for wireless transmission of data, for example via the GSM or other mobile telephony network, from the data logger 60 to a 25 central database 72 and associated user terminal 74. The RFID reader/interrogator 50 and data logger 60 are both mounted to a rail-guided vehicle 76 which travels on the rail network which includes the two rail sections 10 and 12. One such suitable rail-guided vehicle is an 30 instrumented revenue vehicle developed by the Institute of Railway Technology at Monash University in Australia. The instrumented revenue vehicle monitors aspect of railway operations on a day-to-day basis, and includes a fully-automated condition monitoring system (not depicted) which 8 922953 records current network health of conditions throughout the rail network. The instrumented revenue vehicle also collects key information for planning future maintenance and operational strategies. 5 Operation of the system for detecting degradation of a defective insulated rail joint depicted in Figures 1 and 2 will now be described with reference to Figure 3. As a wagon or other rail-guided vehicle passes over the rail sections 10 10 and 12, the strain values of the strain gauges 24 and 26 exceed a predetermined threshold which causes the the capture and storage of the peak strain values from both of the strain gauges 24 and 26 and written to the RFID tag. Accordingly, upon detection of such a trigger condition at step 100, strain values 102 are read from the strain gauges 24 and 26 and captured and 15 stored onto the RFID tag 38 at step 104. In addition, related data such as a time stamp indicating the date and time at which the peak strain values occurred, and error checking data (which cross checks the strain values of the two strain gauges 24 and 26 and flags when there are significant differences), is captured or computed and written to the RFID tag 38 at step 106. 20 As the rail-guided vehicle 76 travels on the rail network, the RFID reader/interrogator 50 continuously emits an interrogation signal. When the rail-guided vehicle 76 passes over the rail sections 10 and 12, the interrogation signal emitted by the RFID reader/interrogator 50 at step 108 is detected by 25 the RFID tag 38. At step 110, the RFID Tag 38 transmits data captured or computed by the RFID tag 38 at steps 104 and 106, that is the most recently recorded peak strain values from the strain gauges 24 and 26, a time stamp indicating the date and time at which the peak strain values occurred, the open-circuit or closed-circuit condition of the strain gauges 24 and 26 as 30 determined by the detection or not of a discernible strain value, as well as the computed error checking data. 9 922953 At step 112, the data transmitted by the RFID tag 38 is read by the RFID reader/interrogator 50. At step 114, the data is transmitted to the data logger 60. At step 116, the data transmitted from the RFID reader/interrogator 50 is stored by the data logger 60 and then, at step 118, the data is used to 5 update a series a data tables maintained in the memory 64 to record the status of each insulated rail joint in the rail network. The hierarchy of data in the stored data tables is used by the data logger 60 to determine the current status of each insulated rail joint as well as 10 the current status of the system elements (strain gauges 24 and 26, control circuitry 28 and RFID tag 38) monitoring the degradation of each insulated rail joint, as depicted in Table 1. Possible RFID tag Recent Both circuits comparable Stable Resulting action response responds? update continuous? strains? strain | on tag? trend? 1 No Local control circuit or RFID tag damaged, malfunctioning or missing 2 Yes No Local control circuit damaged, malfunctioning or missing 3 Yes Yes No IRJ cracked, immediate inspection required 4 Yes Yes Yes No Possible debonding of one gauge, monitoring system needs repair 5 Yes Yes Yes Yes No Degradation of local support resulting in increased local stresses - inspection of ballast required 6 Yes Yes Yes Yes Yes System operational, component performing satisfactorily, no need for attention. 15 Table 1: Hierarchy of RFID responses and subsequent actions The appropriate intervention can be readily determined by the data logger 60 from this table, with responses 3 and 5 corresponding to insulated rail joint degradation. 20 Response 3 results from identification at the data logger 60 that one or both of strain gauges are in an inoperative state, that is, have an open-circuit condition. 10 922953 Response 5 results from identification at the data logger 60 that the measured strain values vary significantly from previous readings, for example, as will occur when ballast supporting an insulated rail joint is displaced resulting in increased local stresses at the insulated rail joint. This will also 5 occur if there is a consistent trend of increased values due to higher external loading of the insulated rail joint, or greater compliance within the insulated rail joint, due to the development of a defect within the insulated rail joint. The significant variation can be identified, for example, if the rate of change of the measured strain value exceeds a predetermined threshold. 10 Responses 1, 2 and 4 correspond to repairs required to the monitoring system. Response 1 results from identification at the data logger 60 that no data was read from the RFID tag. Response 2 results from identification at the data logger 60 that data on the RFID tag was not recently updated due to inactivity or non-operation of the controller in the measurement device. 15 Response 4 results from identification at the data logger 60 that the strain values taken at the same time from the same group of strain gauges are not comparable. It will be appreciated that the use of two strain gauges or crack propagation or detection gauges is useful notably to provide error checking 20 data. However, in other embodiments only one strain gauge or crack propagation or detection gauges, or alternatively more than two strain gauges, or crack propagation or detection gauges may be used. Moreover, one or more other sensors or devices may be used in 25 addition to or in the place of strain gauges, not only to measure the strain of the insulated joint, but also to measure other operating properties of the insulated joint that may be desirous to monitor. The above-described system addresses the need for an independent, 30 active monitoring system to indicate unusually high strain levels, and then cracking at critical components, in this case the joint bars of a rail insulated joint. By monitoring an increase in the local stresses in addition to simply detecting the presence of a crack in the insulated rail joint, the above 11 922953 described system makes it possible to proactively target a maintenance program to improve the support around the insulated rail joint to reduce the stresses, and thereby avoid the initiation of fatigue cracking in the first place. An advantage of this system is that it provides continuously updated 5 monitoring of the critical component, using a very low cost, low power system. It is also to be understood that whilst the system for detecting degradation of a defective component in a rail network has been described in the context of a stationary insulated rail joint, stationary measuring devices, a 10 stationary RFID tag and a mobile RFID tag/reader, many variations possible. By way of example, the invention can be used to detect degradation of a defective coupling between rail carriages. In this case, the strain gauges, control circuitry and RFID tag could be mounted to the coupling of a rail 15 carriage. As the train carriage travels around the rail network, one or more stationary RFID readers/interrogators may be positioned on sleepers or elsewhere to enable the RFID tag to be read at they pass by. In such a system, stresses and cracking on the coupling would be detected prior to coupling failure. 20 Insulated rail joints and rail carriage couplings are merely two examples of components in a rail transport network that may be monitored according to the present invention. 25 Moreover, the present invention is not limited to the detection of the strain of components only. Detection of other operating properties of a component - be they mechanical, electrical, thermal or another operating property - will be apparent to a skilled addressee. 30 It is also to be understood that whilst the invention has been described in the context of a system for detecting degradation of a component in a rail transport network, the invention is also applicable to other transport networks, such as road and air transport networks. For example, strain gauges, control 12 922953 circuitry and an RFID tag could be affixed to a component of a truck or other land vehicle, and that RFID tag read by a stationary RFID reader/interrogator positioned on a road network e.g. located next to a road toll station or on an overhead road gantry. 5 Whilst a number of organizations have set standards for RFID, including the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), ASTM International, the DASH7 Alliance and EPCglobal, the term "RFID" is used herein in a more generic manner to refer to the use of radio waves to transfer data from an electronic tag 10 regardless of the particular low power radio communications protocol that is used. While the invention has been described in conjunction with a limited number of embodiments, it will be appreciated by those skilled in the art that many alternative, modifications and variations in light of the foregoing 15 description are possible. Accordingly, the present invention is intended to embrace all such alternative, modifications and variations as may fall within the spirit and scope of the invention as disclosed. 13 922953