Responding to the Environmental Noise Directive by demonstrating the benefits of rail grinding on the Great Britain's* railway network

This paper investigates a significant reduction in environmental noise attributable to changes in the Network Rail grinding strategy employed within GB. It also considers how these findings could inform noise mapping and action plans required by the Environmental Noise Directive (END). Acoustic track quality (ATQ) is a measure of the surface roughness of the running rails and is proportional to wayside rolling noise levels during the passage of a train. Levels of ATQ have been determined for approximately 1100km of track on GB's East and West Coast mainlines from wayside noise measurements made during the pass-by of Network Rail's New Measurement Train and data collected by an under-carriage microphone system fitted to this train. The results show a substantial apparent reduction in rail surface roughness and associated wayside noise levels since a similar study was undertaken in 2004. While these findings require further verification they are supported by initial direct rail head roughness level measurements which also show low levels of roughness. The results of the study show how a maintenance rail grinding strategy can potentially reduce wayside noise levels across large parts of a railway network. While the measure of track quality used to evaluate the benefits of a maintenance rail grinding strategy is specific to GB's method for calculating railway noise, the results also provide insight into the potential benefits of maintenance rail grinding on networks outside of GB. In addition the results demonstrate the importance of including a track quality parameter, such as ATQ, in any prediction methodologies for rail noise used in noise mapping exercises, such as those being undertaken as part of the END.