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30 gage wear can affect the amount of wheelset lateral shift in Clearly setting the objectives of wheel/rail profile moni- curves. Therefore, an installation clearance and a wear limit toring and prioritizing the emphases would make the moni- should be specified in order to maintain the vehicle curving toring program more effective and efficient. performance in a desired range. Note that track lateral geometry irregularities including alignment and gage vari- ations can also affect the performance of restraining rail. 3.9.2 Establish a Monitoring Program to Meet the Objectives No specific suggestions are given in this report regarding this clearance. The research team has proposed a study on A wheel/rail profile monitoring program should define the this issue to further investigate the relation of wheel/rail following basic requirements: force, clearance, and track curvature. Measurement interval 3.9 WHEEL/RAIL PROFILE MONITORING Measurement sample rate PROGRAM Distribution of measurement sites Measurement accuracy requirement A well-structured wheel/rail profile monitoring program Required measurement devices can be an effective tool for detecting system performance and Documentation procedures prioritizing maintenance needs. Analysis procedures Reporting procedures 3.9.1 Objectives of Profile Monitoring Depending on the objectives, more detailed descriptions can be included in the program. The emphases of monitoring may differ for various sys- Note that the measurement interval should be set based on tems depending on the existing vehicle and track conditions. the loading and operation frequency, so as to correctly reveal For example, lower speed operations may pay more attention the trend, but not so short that it would increase the monitor- to vehicle curving behavior and wear issue since high speed ing cost. The sample rate should be sufficient to provide instability is of no concern. Meanwhile, vehicle stability may information that would be representative of the wheel/rail become an issue for a higher speed operation. populations. The monitoring objectives can be defined into short-term For monitoring rails, key locations in the system should be and long-term objectives. The short-term objectives usually marked. Here the measurements should be performed at identify the problems that might be related to wheel/rail pro- exactly the same locations in order to accurately determine files or that the shapes of wheels and rails might provide the changes of profile due to wear. Wheels selected for mon- some indication of, such as flange climb derailment poten- itoring should be marked to trace the profile changes. tial, poor steering, and excessive wear. The long-term objectives relate to system optimization, management, and maintenance. According to the performance 3.9.3 Integrate the Profile Monitoring Program trends and the wear patterns, a system level of improvement into Vehicle/Track Maintenance Program may be approached. For example, if an excessively high wear rate was observed on curves during rail profile monitoring, As discussed previously, results of wheel/rail interaction several related factors may be looked at, such as lubrication, are not only related to wheel/rail profiles. They are also wheel/rail profiles, restraining rail clearance, and the condition affected by the vehicle and track conditions in that system, of vehicle suspension components. If wheel flange wear most often vehicle suspensions, track geometries, and lubri- becomes excessive, as indicated by a thin flange, then track cation. In many cases, the improvement of vehicle perfor- gage, vehicle curving performance, lubrication, and possibly mance or wheel/rail wear relies on the combined improve- the symmetry of wheel diameters on the same axle may need ment in wheel/rail profiles, track maintenance, and lubrication. to be inspected. The sections that showed less satisfactory per- Therefore, the profile monitoring program should be integrated formances would get special attention. into the vehicle/track monitoring/maintenance program.