ISO 3381:2021 PDF Download

The ISO 3381:2021 standard is a detailed document that outlines the procedure and circumstances for determining reproducible noise levels within railbound vehicles. With the exception of track maintenance vehicles, this standard applies to all types of vehicles operating on rails or other fixed tracks. It is just meant for type testing and does not involve monitoring testing or evaluating noise exposure throughout the course of a trip.

The standard specifies measurement procedures for various scenarios, including when the vehicle is moving at a constant speed, when it is stationary, when it is accelerating or decelerating, and in the driver's cab when an external warning horn sounds (which is especially important for European Union regulation compliance). It does not, however, provide processes for determining the audibility or intelligibility of audible signals or evaluating warning devices other than warning horns.

The standard's scope also excludes assessing train crew noise exposure as a result of operational conditions. The results of the procedures outlined in this standard can be used for a variety of purposes, including characterizing the noise inside railbound vehicles, comparing the internal noise of different units on a specific track section, and collecting fundamental source data for these units.

The ISO 3381:2021 test techniques are designated as engineering grade (grade 2), which is the preferred grade for ISO 12001 noise declaration reasons. When test conditions are relaxed, such as when monitoring in-service trains, the results are no longer deemed engineering-grade. In contrast, the processes for accelerating and decelerating tests are designated as survey grade (grade 3), resulting in a less rigorous examination in these specific scenarios.