Multi-use highways: the Poggio Moiano case study

This paper relates to a design proposal answering the call for tenders issued by the Italian Ministry of Public Works about "pilot projects", i.e. test innovative interventions and projects aimed at improving road safety and at reducing the number of fatalities. The proposal, here presented, refers to the class concerning "Urban areas and land structures", at the point "Change from extra urban to urban road system". It represents a typical case of a National road (with its heavy traffic and its safety problems) that enters an urban area without appropriate devices for alerting drivers of the change of context. Highways and streets should be designed to meet the requirements of their specific class of users; problems arise when the users' needs are in conflict. In this sense, the crossings of small towns by national highways are very critical spots, since the perception and the use of the same space is completely different for highway's drivers and local users. In the considered case study, the National Highway Salaria, a consular road, passes through the small centre Osteria Nuova, part of the little town of Poggio Moiano, without significant changes of the road's geometrical characteristics; as a result, the 50 km/h speed limit, signalised at the urban area entrance, is not considered by most of the drivers, who, according to the police measurements, cross the area at speeds often faster than 100 km/h. The accident rate is very high and the severity index is 100 higher than the national one. The aim of the intervention is to improve the safety level of the highway, both for drivers and pedestrians, by the implementation of a system of measures targeted to induce users (mainly car drivers) to behave in a more respectful way, according to the rules in force and to the road functional features