This document specifies a method of comparing traffic noise on different road surfaces for various compositions of road traffic for the purpose of evaluating different road surface types. Sound levels representing either light or heavy vehicles at selected speeds are assigned to a certain road surface. The method is applicable to traffic travelling at constant speed, i.e. free-flowing conditions at posted speeds of 50？km/h and upwards. For conditions where traffic is not free flowing, such as at junctions and where the traffic is congested, the method is not applicable.

A standard method for comparing the noise characteristics of road surfaces gives road and environment authorities a tool for establishing common practices or limits regarding the use of road surfaces meeting certain noise criteria. However, it is not within the scope of ISO？11819 (all parts) to suggest such criteria.

The statistical pass-by (SPB) method is suitable for use for the following main purposes:

—？to classify road surfaces according to their influence on traffic noise (surface classification);

—？to assist in verifying conformity of production of road surfaces;

—？to evaluate acoustic performance of road surfaces throughout operation relative to new condition;

—？to evaluate the influence of different road surfaces on traffic noise at sites irrespective of condition and service time;

—？to evaluate acoustic performance of a road surface relative to a reference surface.

Due to practical restrictions, the method cannot be applied at all possible locations. However, the backing board method can allow some locations to be tested that were not previously acceptable.

Clause？5 gives a general description of the SPB method.