APPLICATION OF DESIGN CONSISTENCY EVALUATION TOOLS FOR TWO LANE RURAL ROADS:A CASE STUDY FROM ITALY

摘要

The operating speed-profile model is an effective tool for the safety analysis of new and existingroads since it can be used for checking speed consistency violations. However, to effectively usethe operating speed-profile it is necessary that it accurately predicts the speed along the road.Therefore, the Design Consistency Module (DCM) of IHSDM (Interactive Highway SafetyDesign Model) and the recently developed model for the Italian context were applied to a realItalian two-lane rural road in rolling terrain with a complex alignment to evaluate their capabilityto fit the observed speeds. The comparison of the operating speed-profiles revealed that theDCM usually predicts operating speeds higher than the Italian model, whereas the comparisonbetween the predicted speeds and the observed speeds indicates that the Italian model fits slightlybetter the observed speeds on this type of road. All told, both the models predict quite well theobserved speeds, even though there are cases in which the complex alignment strains theconstruction rules with the results that the predicted speed-profiles are not appropriate. Theresults of this case study are useful both to practitioners for a correct use of these models and toresearchers for identifying future research needs in an attempt to improve the capability of themodels to predict speed-profiles that conform to the real speed observed.