Maria Macchiaroli

Water, sewerage, and gas infrastructures play a crucial role in optimising the housing quality of buildings and cities. On the other hand, water, sewer, and gas pipelines constantly need maintenance, checks, and repairs. These interventions require large budgets, and therefore scrupulous investment planning is necessary. In this study, Multiple Regression Analysis (MRA) is applied to estimate the urban renovation costs related to the works on water, sewage, and gas networks. The goal is to build a reliable cost estimator that is easy to apply and has a minimum number of explanatory variables. Four regressive models are tested: linear, linear-logarithmic, logarithmic-linear, and exponential. The analysis is implemented on two datasets of projects carried out in Italy: the first collects the data of 19 projects made in historical centres, while the second collects the data of 20 projects made in the peripheries. The variables that impact costs the most are selected. In terms of results, the estimated functions return an average error of 1.25% for historical centres and 1.00% for peripheral areas. The application shows that a differentiation of cost functions based on the urban context is relevant. Specifically, two different functions are detected: exponential for historical centres and linear for peripheral areas. In conclusion, we interpret that the exponential growth of costs in historical centres depends on a series of critical issues (logistical, architectural, etc.), present to a lesser extent in the peripheries, which complicate the execution of the interventions. The approach adopted, which led to the detection of cost functions differentiated based on the urban context, allows us to benefit from more accurate modelling that considers the places’ specificities.

The United Nations SDG6 goal of ensuring universal access to safe drinking water and sanitation by 2030 will require increased investment in the rehabilitation and maintenance of water infrastructure. In Italy, the water sector has not yet reached the performance of other European countries. The hierarchization of investments is essential for identifying priorities and efficiently allocating resources. This issue is part of the debate on the reconciliation of public and private needs in the management of water services. The present research proposes a model based on the analytic hierarchy process (AHP). Taking into account the design alternatives considered optimal that contribute to the resolution of territorial criticalities, the model organizes them in a ranking that indicates the chronological priorities to be respected in the investments to be made. The evaluation criteria are set in compliance with the norms defined by the National Authority (ARERA). The model is tested on a water manager in the Campania region. Among the main results, it is found that the two extremes of the ranking are shared between the two actors involved in the investment strategy (the private operator and public regulator). The model represents an effective tool for identifying shared planning strategies between public and private operators.