BS EN ISO 3381:2021

What is ISO 3381 about?  

ISO 3381 specifies the measurement method and conditions to obtain reproducible noise levels on-board all kinds of vehicles operating on rails or other types of fixed track, hereinafter conventionally called “unit”, except for track maintenance vehicles in working modes.  

ISO 3381 provides measurement procedures for vehicle interior noise (in general, a vehicle type test is carried out using only a selected subset of these tests): 

• When the vehicle is moving at a constant speed 
• When the vehicle is stationary 
• When the vehicle is accelerating or decelerating 
• In the driver's cab when an external warning horn is sounding (specifically required for European Union regulation application). 

NOTE: ISO 3381 does not include all the instructions to carry out monitoring testing or evaluation of noise exposure of passengers or drivers over a whole journey. 

NOTE: This document is not applicable to guided buses. The assessment of noise exposure of train crew due to operational conditions is not in this document. 

NOTE: This document does not provide measurement procedures for: 

• Audibility or intelligibility of any audible signals 
• Assessment of warning devices other than warning horns. 

Who is ISO 3381 for? 

ISO 3381 on railbound vehicles acoustics is useful for: 

• Railway engineer 
• Train operators  
• Meteorological department 

Why should you use ISO 3381?  

Roughness and irregularities on the wheel and rail surfaces are a source of noise and vibration. ISO 3381 specifies the noise measurement inside railbound vehicles. 

ISO 3381 gives information regarding the sound calibrator and instrumentation like microphones, signal acquisition units and processing algorithms used in railways to analyse frequency bandwidth. 

ISO 3381 lets you know about the characteristics of noise inside the rolling stocks and comparison of the internal noise of various units on a particular track section to collect basic source data for units, this data will let you analyse the noise profiles of different parts. In this manner, you will be able to create an efficient and noise-free functioning of the railway infrastructure. 

What’s changed since the last update?  

BS EN ISO 3381:2021 supersedes BS EN ISO 3381:2011. BS EN ISO 3381:2021 includes some technical changes with respect to BS EN ISO 3381:2011. These include: 

• New structure of the document to align it with the structure of ISO 3095 
• New measurement procedures for noise in driver's cab  
• An improved assessment of the tonality  
• An improved indirect assessment of the track acoustic characteristics  
• Precisions for measurement in specific environments (tunnels, …)