The speed-profile is a useful tool for road safety both in the design process and in the evaluations of existing roads because the availability of the operating speed on each point of the alignment can be used for severalsafety considerations. Unfortunately, however, the existing operating speed-profile prediction models do not take into consideration the presence of intersections along the road since a procedure to estimate a reliable operating speed-profile on the road section along which the speed is affected by the intersection presence is not currently available. This limitationis particularly relevant when the model is used to analyze roads characterized by a significant presence of intersections as usually happens in territories that have a widespread distribution of urbanized areas. The consequence of this limitation is that the speed-profile is less reliable precisely in correspondence to the intersection which is a critical point of the road from the safety point of view and, therefore, one that should be carefully evaluated in all its aspects. To overcome this limitation, speed behavior approaching and departing from at-grade intersections with stop control and modern roundabouts with yield control were studied and a procedure to predict the operating speed-profile along a road section characterized by the intersection presence was developed. This simple procedure is integrated into the construction rules of the existing operating speed-profile models and it makes it possible to predict a reliable profile in proximity of at-grade intersections and roundabouts, thus improving significantly the possibility of applying this useful tool.
Samenvatting