naSRPS EN 16891:2025

Railway applications - Acoustics - Measurement method for combined roughness, track decay rates and transfer functions

Scope

The method described in this document is used to determine combined wheel-rail roughness and track decay rates from rail vibration during the pass-by of a train. By combining sound pressure measurement from the same pass-by, a vibro-acoustic transfer function for rolling noise is determined.
This document describes a method for the following purposes:
— to measure track decay rates under operational conditions;
— to characterize the effectiveness of noise control measures in terms of combined roughness, transfer function and track decay rate;
— to compare the combined roughness before and after noise control measures are implemented (thereby quantifying the effect of any change in wheel or rail roughness);
— to monitor wheel roughness during a pass-by, either of whole trains or parts of trains;
— to separate rolling noise from other sources;
— to assess a threshold for the rail roughness, by measuring multiple pass-bys;
— to obtain combined roughness and transfer functions for input to environmental noise calculations.
The method is not for approval of sections of reference track in terms of acoustic rail roughness and track decay rates, which are covered by EN 15610:2019+A1:2025 [9] and EN 15461:2008+A1:2010 [10], respectively.
The method is applicable to trains on conventional tracks, i.e. normal ballasted tracks with wooden or concrete sleepers and on slab tracks.
Annex A and Formula (A.1) give guidance on the calculation of the A2 factor, if the method is applied to:
— non-standard wheel types such as small wheels, resilient tram wheels;
— non-standard track types such as embedded rail or grooved rail.