Effects of temperature and humidity on railhead friction levels

Abstract

This paper explores the research gap involving the links between railhead temperature, relative humidity, and coefficient of friction (adhesion level) at the wheel/rail interface as found on track across the UK. Existing work done in this field has mostly been carried out in laboratories which limits variation of environmental conditions. Weather and friction data were collected from different sites across England, generating a real representation of the railhead conditions. Correlations were established between the environmental dataset and the railhead friction to give a greater insight into the mechanisms of low adhesion and when low adhesion can be expected to take place. This can provide an avenue to better predict the occurrence of low adhesion in the wheel/rail interface, therefore improving safety within the rail network. Results from the data analysis showed that high humidity conditions, independent of the railhead temperature, reduces the adhesion level on the railhead. Showing that low adhesion can occur in warmer temperatures, such as those typically experienced in early autumn where there is high relative humidity.

A Machine Learning Approach for Real-Time Wheel-Rail Interface Friction Estimation

“…The methodology established by Folorunso et al was used in this work, and described briefly here. For a complete description refer to [18]. Friction measurements were taken by a pendulum tribometer.…”

“…The outcomes are shown in Table 1. Folorunso et al have extensively discussed different methods of friction measurements and describe the methods described in Table 1 in more detail and more analysis was done using the data collected (discuss further in this paper) to understand the environmental influences (such as relative humidity and railhead temperature) on railhead friction [18]. The pendulum tribometer was selected as the friction measurement method for this project because it is easily accessible, portable and simple to use.…”

Rail-wheel friction quantification and its variability under lab and field trial conditions

“…Despite the unavoidable variation in environmental and contact conditions when field testing over long time periods, both devices were able to distinguish between the low, intermediate and high friction conditions which were simulated during this testing. Previous work has linked the variability of the friction coefficient with these changing environmental and contact conditions, such as the reduction of friction with increased humidity and variation with temperature 18 and the reduction of friction due to increased third body layer 29…”

“…Railhead friction studies have been carried out with a pendulum slip resistance tester 16–18 and the results of low and high friction conditions correlate well to other friction measuring methods, however, the sliding rubber contact is difficult to relate to the real rail and wheel steel rolling/sliding contact. Errors are easily introduced by the user due to the complex set-up procedure and operator dependency and results are affected by high winds.…”

“…This limits the push tribometer usability in the UK where there is a focus on measuring low friction caused by organic railhead contamination, due to a wet climate, deciduous leaf cover and short intervals between station stops. 14,15 Railhead friction studies have been carried out with a pendulum slip resistance tester [16][17][18] and the results of low and high friction conditions correlate well to other friction measuring methods, however, the sliding rubber contact is difficult to relate to the real rail and wheel steel rolling/ sliding contact. Errors are easily introduced by the user due to the complex set-up procedure and operator dependency and results are affected by high winds.…”