A procedure for determining the industrial profitability of settlement interventions in the appraisal of exceptional contribution of urbanisation

The exceptional contribution of urbanisation (hereinafter simply exceptional contribution) is a regulatory obligation that represents an additional to the costs of primary and secondary urbanisation, at least equal to 50% of the greater value generated by projects in areas or buildings with modifications to town planning. The rule that introduced the exceptional contribution does not indicate the factors to be considered while evaluating the exceptional contribution, and consequently does not address the evaluation procedure to be used in determining its exact form. In this paper, an idea will be proposed regarding the urban development exceptional contribution as it has been applied in Italy both in regional regulations and in various Local Authorities. From this overview, the approach of the different LAs can be seen. Each has autonomously decided upon the adoption of an analytical procedure to estimate the Transformation Value to calculate the extra contribution. Subsequently, in light of the result of not considering a specific rate of return during the estimation of the exceptional contribution, a procedure is proposed for determining the rate of return to be considered in the indirect analytical procedure for estimating the Value of Transformation used to calculate the exceptional urbanisation contribution. The proposed procedure is based on the Build-up Method and will take the form of its operational declination, to be used when one has the coefficients representative of the areas of risk for the different factors that are typical of interventions of settlement transformation. To test the proposed procedure it has been applied to a case study: the evaluation of exceptional contribution in an Integrated Intervention Program in the Municipality of Grottaferrata (RM).