The primary intent of this study is to evaluate the effectiveness and utility of a laser-based measurement unit for qualitative assessment of the presence and amount of Top-of-Rail Friction Modifier (TOR or TORFM), at reasonably high speeds and over long distances in the field. As a capstone to this phase of development, a series of field tests were conducted on revenue service track in partnership with a local Class 1 railroad. For these tests, the Third Generation Rail Lubricity Sensor was mounted on a Remote-Controlled Rail Cart and tested continuously over several miles of track. This longer window is able to cover the domain of multiple wayside applicators over a distance of more than 3 miles, the expected carry distance of TORFM.
The results of this testing demonstrate the capacity of optical sensors to measure and evaluate track lubricity. The signal characteristics at or near wayside applicators demonstrate a clear impulse from the heavy lubricant close to the applicator. Further, by collecting continuous data down track from a wayside applicator it is possible to observe several novel ways in which the TORFM and flange grease carries beyond the point of application. One such example is a clear spike in track lubricity when entering or exiting curves caused by the lateral shift of the wheelsets drawing fresh lubricant previously out of contact with the rail into contact creating a “phantom applicator” effect. These observations are crucial to understanding in detail the way the TORFM and flange grease is carried down track. They are also essential to creating predictive models for most effective application of friction modifiers to specific track geometries.