The monetary evaluation of the transport noise social cost: the use of the continuous attribute-based SC method

In the last decades, several studies have been undertaken to evaluate the social costs of transport, most of them to define appropriate pricing policies for their internalization. The importance of this issue has been highlighted by the interest of European Commission in funding projects to harmonize the approach of evaluation of external costs produced by transport systems. Even if several European projects have been carried out to set up effective methods to evaluate them, as EXTERNE, UNITE and HEATCO, and have proposed some unified methodologies, what is missing yet is a data set covering all the EU countries (and not only) to test the proposed methodology and, above all, the goodness of the hypotheses adopted when the benefit transfer function is used. This research wants to set up a methodology to evaluate the transport noise cost, supporting the decision makers in their choices related to transport planning and construction of new infrastructures. To this extent, the paper proposes to adopt the dose-response method, broken down in four steps: 1) calculation of the noise emissions; 2) use of the dose-response relationship to calculate the number of highly annoyed person per year; 3) use of economical evaluation methods to monetize the damage; 3) calculation of the noise costs produced by the infrastructure. However, the proposed method provides a change in the steps 2 and 3, to overcome the current weaknesses envisaged in literature, introducing a new approach, the continuous attribute-based stated choice method. This technique allows the respondents to define their best "noise" pattern, choosing the desired values of different attributes, through sliders moving on a continuous scale, and observing the effect of their choices on the cost. In this way, the respondents face only one game reporting a full factorial design, avoiding the fatigue effect and being stimulated by an appealing layout. The new proposed SP approach seems to have big potentiality, allowing both to estimate the importance given to each attribute and to evaluate individual WTP (and not an average WTP of a homogeneous group of individuals), if a proper and non linear cost function is availabl