This paper is divided in two parts: the first is relative to the formulation of risk theory for the analysis and prevention of road accident; the second part is relative to a before and after experimental application of road risk functions in the field of accidents between car and pedestrian. The safety committee could evaluate the possibility to divide the paper in two different presentations. Part 1: the risk theory application to road safety. In this paper the definition of risk is analyzed in depth, in the single factors individual which compose it. The specific formulation is proposed in the case of road accident involving pedestrians, with indicators identifying inside the proposed function. The risk has been defined since the '70 (with a frequentistic or probabilistic approach) as unwanted consequence of a specific activity related to the probability of it happening. Considering the definition of risk that depends on the probability P (or the frequency) that the event occurs and on the magnitude M of the loss, injury, or damage, in a simplified version, can be defined as: R = f(P,M) The magnitude M can be considered as depending on two terms: the vulnerability V and the exposure N. The equation for risk evaluation can be also written in the form: R = f(P,V,E) In this paper a general formulation for risk analysis is proposed with specific reference to road safety. Opportunity to analyse road accidents according to classic risk theory represents an useful instrument for planning the actions for road risk reduction. Considering the risk components the actions for risk reduction are: actions for probability or frequency reduction, (named prevention), consist in activities to eliminate the causes of the accidents or his intensity; actions for magnitude reduction, (named protection), consist in activities to reduce the accident related damages. Part 2: experimental application In Italy, casualties in pedestrians related accidents are respectively 12.7% and 5.4% on the total road accident occured in 2003. This experimentation is developed in the following steps. (1) The Study of the scenarios of road accident with pedestrian at an urban level proposed in literature. (2) Definition of the indicator for each scenario tied to the probability or frequency and magnitude.(3) Identification of black spots in the city of Reggio Calabria (Italy), in relationship to the indications given by the scenario analysis. (4) Data acquisition with the monitoring in the black spots. (5) Estimate of indicators relative to the frequency and magnitude relative to road accident.(6) Actions on the system for risk reduction. (7) Valuation of the results with before and after methodology in order to evaluate costs/benefits. For the covering abstract please see ITRD E135207.
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