Standards Development

Scope

This Technical Specification advises on methods for measuring and analysing irregularity of the running surfaces for use in the prediction and assessment of ground-borne noise arising from railway systems.

The scope is to:

a) define the data that can be described as rail or wheel roughness and used to quantify a source term for the generation of the dynamic forces that can lead to ground-borne vibration from railway vehicles;

b) advise on the general types of measurement equipment for roughness as a variation of height along the running direction of the rail surface or on the wheel perimeter;

c) advise on the methods of obtaining an estimate of the wavelength spectrum of roughness from measurement records over a length of rail head or on the wheel perimeter;

d) advise on the presentation of a roughness spectrum representing the condition of a length of rail or of a wheel relevant to its generation of vibration.

Purpose

Rail roughness refers to the unevenness of the railway rolling surface and, combined with the wheel roughness, it determines the amount of vibration energy induced by the passage of a train. It is therefore a key parameter for the prediction and assessment of train induced ground-borne vibration. Methods for measuring, assessing and presenting rail roughness for the purpose of airborne rolling noise are well established and widely used (e.g. EN 15610:2019, Railway applications — Acoustics — Rail and wheel roughness measurement related to rolling noise generation). For assessing roughness for prediction of ground-borne noise the principles must be supplemented so that they are relevant for low frequency vibration. Measurement techniques capable of capturing roughness at longer wavelengths are also required.

Despite the importance of this parameter, there is currently very limited guidance for assessing roughness which is relevant to train induced ground-borne noise and vibration. This lack of information leads to increased uncertainty of the prediction of ground-borne noise and vibration and often means that rail roughness is not given adequate consideration in the design of railway schemes. The members of ISO/TC 108/SC 2/WG8 consider that there is now sufficient body of evidence and experience to enable guidance in this area to be documented and published by ISO as a Technical Specification. Collectively the members of ISO/TC 108/SC 2/WG8 have the experience, gained working in both academic and industrial contexts, required to author new guidance in this area. This guidance would be of value internationally to railway infrastructure maintainers, railway track designers, promotors of railway schemes, academic institutions and engineering consultants alike.

A previous approved work item (Ref: NWIP has been approved: ISO/TR 14837-34 Roughness - Result of Voting under ISO/TC 108/SC 2/WG 8 N 402 dated 2018-03-21 and Template for comments ISO/TC 108/SC 2 N 943 dated 2018-03-11) enabled the WG to develop the document to the standard of a Technical Report according to the NWIP approved. The members consider that it would be valuable to develop the draft TR into a TS: Technical Specification. This NWIP is for the work required to do this.