A decision support system for the safety of airport runways: The case of heavy rainstorms

Hydroplaning caused relevant plane accidents in landing and taking off phases. A decision support system is here proposed in order to assess the safety standard during heavy rainstorms. The geometry of the runways and the pavement characteristics are investigated in different hydrological conditions. The decision support system outcomes show that the very short rainstorms (duration of about 5 minutes) are the most critical. The decision support system dynamically computes the depth of the water film through a hydraulic model, which numerically integrates the complete energy and mass differential equations. The reliability of the mathematical solution of the varied flow algorithm is validated. A conceptual, physically based, model is proposed to simulate how the skid resistance decreases during the rainstorm. This model, called ‘three points’ model, fits well the existing models both for a low water film and for a deeper one. It is integrated in the decision support system so that an analysis of the skid resistance during rainstorm is possible. The role of the pavement macrotexture is investigated for different slopes of the runway surface and in different hydrological conditions (return period of the event and duration of the rainfall). It is interesting to underline that the skid resistence increases with the macrotexture, though the water film is deeper during poor weather conditions. Moreover the safety conditions can be completely investigated. Finally the open graded pavements are considered. The infiltration into the pavement texture seems to be the best solution to reduce the hydroplaning risk and the reliability of landing and taking off in poor weather conditions. Then the decision support system can be considered a strategic diagnostic tool, for the runway management, in order to identify the critical rainstorm that crucially makes the airport unsafe. And, at the same time, the decision support system is a useful tool to choose the geometry (runway slope) and the pavement materials (texture), in the project phases.