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The dynamic interaction that occurs at the rail/wheel interface of any rail system is significantly influenced by rail and wheel profiles. In an effort to enhance this interaction, railways and transit systems often employ rail grinding as a means to maintain a defined rail profile. The cost to perform this procedure can be very high, sometimes exceeding $DLR25,000 per day for the use of a large grinding machine (with up to 128 grinding motors--each motor being 20 hp or more). Because of this, it is imperative that the work be done efficiently and accurately. In recent years there has been substantial research into the optimization of rail profiles. The National Research Council (NRC) of Canada is one research facility that has generated a unique, precise set of specified profiles for use in heavy-haul railway operations. To implement these profiles in a consistent manner, during rail grinding operations, requires some type of measurement system that provides feedback to the field staff. Up until recently, this has been accomplished with a manual BAR gauge that is fitted with a set of accurate profile templates. The BAR gauge, which initially was fitted with four specified templates, is now equipped with ten such templates. To obtain the full potential of benefits from these profiles requires more precise grinding than that which has been achieved in the past. The other problem with the current manual profile measurement (BAR) method is that it is somewhat slow and cumbersome and the differences between profiles is quite small (i.e. 0.020 inch or less). In order to enhance their rail grinding management support, ARM pursued an automated system that would optically measure rail profiles very fast and accurately from a hy-rail vehicle and compare them with the NRC profiles. Another important feature that was desired in this system was the ability to measure the relative position of one profile with respect to the other (i.e. left versus right rail). Such a system would thus be able to look at both rail profiles in one x-y plane, which is what the manual BAR gauge provides, to produce an electronic simulation of the desired templates oriented with each other in the proper manner, and compares this with the actual profiles. In order to compare actual profiles with the NRC profiles, it is necessary that both rails be looked at simultaneously in one x-y plane. This is mandatory if you want to duplicate the capabilities of the manual BAR gauge. Other parameters such as cant angle, head loss, track gauge, and section rail weight are also calculated at the same time. After evaluating various technologies, ARM selected the Electronic BAR Gauge, manufactured by Range Vision Inc. of Canada. The Electronic BAR Gauge is a second generation piece of equipment that enables you to measure rail profiles and wear within a resolution of 0.001 inch. It is utilized ahead of the grinding program to create a pre-grind survey plan and during grinding operations as a quality control device to verify desired profile installation and to monitor metal removal rates. The Electronic BAR Gauge will help ARM move towards the next generation of rail grinding strategy; namely being able to grind in a true preventive manner, whereby the work is carried out in a predictive manner with just the right amount of metal being removed from the rail in just the right places. This is referred to as the 'magic wear rate'. This paper presents the features of the Electron BAR Gauge, concentrating on how the system has been specifically designed to meet the needs of ARM for their rail grinding applications. Another section describes the accuracy requirements of the system and provides insight on the technology utilized.
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