**1. Introduction**

The European Law [1], developed in Spain by the Royal Decrees [2, 3], states that noise maps in cities with a population in excess of 100,000 individuals need to be developed and updated every 5 years.

A noise map can be done just based on a prediction model, that is, without any kind of empirical measurement; but to achieve a minimum accuracy level, a calibration of the model is required through a selected number of in-situ measurement points, which increases the budget to carry out the noise map. Moreover, although specific standards and a good practice guide [4] have been defined to be used in noise maps, each research group defines its own methodology based on its experience and the characteristics of the town. Therefore, a proper balance must be found among the cost of the noise map, its accuracy, and the number of measurement points; that

balance can be improved with the use of a road categorization system to achieve representative measurements of all the types of roads to minimize the cost without losing accuracy in the model.

Classically, four sampling methods have been considered: to select the sampling points by laying a grid over a map of the target zone, to define a source-oriented sampling where measurement locations are selected arbitrarily to represent different road and traffic conditions, to define a receptor-oriented sampling in which the noise exposure of a particular class of receptors is investigated, and to select the sampling points using a prior classification of the urban noise [5].

In [6] sampling points were selected, covering all of the representative locations and all of the streets in the area. The sampling points were always in the middle of the street or location-specific. This methodology for selecting sampling points and locations allows performing a detailed study of the area and it is not based on a previous categorization of the streets, but neither is similar to the commonly used grid method.

Preliminary studies of three towns [7–9] served to adapt and optimize the definition of the categories established in [10]. This definition consisted of six categories:


The categorization method was later applied in [11] to five medium-sized Spanish towns with populations ranging from 218,000 down to 50,000, and later in [12] to 20 towns with sizes ranging from 2200 to 700,000 inhabitants, and with areas between 0.57 and 59 km<sup>2</sup> .

In this work, a methodology based on a street typology classification is proposed to carry out noise maps. This methodology, recently validated in [13, 14] allows allocating the mean power and the temporal behavior to each street from its characteristics and the time profiles measured with semi-permanent noise monitoring systems. Because of this, as the streets are classified a priori in different typologies, the number of measurement points is reduced maintaining the accuracy of the noise map and reducing the measurement cost. The proposed methodology has been applied to the noise map of Cuenca.
