Interval analysis applied to road standard controls

This paper deals with the application of an analytical technique known as ‘interval analysis’ to the usual audits contained in international road standards. Generally, a design solution is constrained by a number of parameters (dependent on the morphology of territory, on existing conditions, on type of road, etc.) that, materially, cannot exceed certain values. Although the final choice is respectful of these constraints, the ordinary calculation techniques do not allow use of the full potential of the most critical variables. In order to determine all the possible solutions of the problem, the so-called interval analysis, which is generally used to treat uncertain problems when only the limits of existence of uncertain variables but not their probabilistic characteristics are known, was used. The application to the visibility of a horizontal curve has allowed different solutions to be identified, by starting from the knowledge of the range of existence of one or more input variables and isolating the result which was more convenient for that specific situation. This procedure is easily applicable to the design of new or existing roads, especially when one or more variables of the problem are close to the threshold imposed by the standards.