A NUMERICAL PROCEDURE FOR ASSESSING RISKS FROM ROAD TRANSPORT OF DANGEROUS SUBSTANCES

This paper describes a general procedure developed to evaluate individ ual and societal risk connected with transport of dangerous materials to and from factories. The procedure, which can be extended to rail an d pipeline transport with minor changes, is applied to road transport of toxic or flammable substances such as ammonia, chlorine, LPG and ga soline. Typical vehicle accidents are identified and characterized reg arding the probability of occurrence and the rate and duration of the release, and a consequence analysis is performed for each accident and physical effect distribution obtained. The vulnerabilities and the un it risk of the tanker are then calculated and the movement of the poin t risk source (the vehicle) on the route is accounted for without furt her calculations but simply by an accurate translation procedure. The expressions useful for evaluation of individual and societal risks are reported and discussed, focusing attention on modelling of population distribution. A condensed discussion is also given on criteria which could be adopted to judge risk acceptability. The procedure has been i mplemented In a computer program and test results are used to underlin e the main features of the calculation method.