Top-of-rail friction control for curve noise mitigation and corrugation rate reduction

Abstract

Top of rail Friction Modifiers are designed to control frictional characteristics at the wheel-rail interface that influence noise, corrugations, and lateral forces. Key characteristics of the resulting thin film are 1) controlled intermediate coefficient of friction and 2) positive friction, to reduce rollslip oscillations related to both curve squeal noise and short pitch corrugation development. Practical results are presented on the effect of friction modifiers on curve squeal and flanging noise generation at a range of European mass transit sites. Noise reductions ranging from 6.3 to 22.8 dBA were recorded, with an average reduction across the different test sites of 12.0 dBA. Both top of rail squeal and flanging components of noise were reduced.The effect of friction modifier on short pitch corrugation development was evaluated over several years at two curves at Metro Bilbao. Under conditions where corrugations grew from 0.01 mm to 0.05 mm in eighteen months under baseline conditions, with application of friction modifier essentially no corrugation growth occurred in an equivalent time period.

The effects of top of rail friction modifier on wear and rolling contact fatigue: Full-scale rail–wheel test rig evaluation, analysis and modelling

“…Top of rail (TOR) friction control technology has emerged in recent years for reducing curve noise, lateral forces, rail wear, corrugations and fuel consumption [12][13][14][15][16][17]. TOR friction modifiers (FM) used for this purpose have two features of particular interest for RCF control:…”

New laboratory methodologies to analyse the top of rail friction modifier performance across different test scales

“…They primarily aim to reduce RCF, wear, noise and corrugation therefore reducing maintenance requirements and improving safety. This is achieved through improving steering in curves, hence reducing lateral forces and a reduction in stick-slip oscillations [3]- [11]. They allow greater deformation of the third body layer and therefore maintain positive friction characteristics up to higher creep rates.…”

Effect of Control Measures on Wheel/Rail Noise When the Vehicle Curves

“…In the process of curving, a series of railway wheel modes (particularly the wheel's axial modes) are easy to be excited, which may lead to curve squeal [1][2][3]. Known practical solutions for railway squeal in a particular curve include friction modification [4,5] and wheel damping treatments [6][7][8][9]. These solutions can reduce the occurrence of squeal for some special circumstance.…”