This study deals with a group of very severe accidents occurred on the "Serenissima" A4 motorway, from Brescia to Padua in Northern Italy, in the 1983-1992 period. The study analyses 12 cases in which 475 vehicles, including 170 wounded and 21 dead car users, were involved. The analysis shows that the occurrence of the "catastrophic" accidents is related mostly to both bad weather and to the promiscuity of light and heavy traffic. This occurrence is usually triggered by sudden traffic flow alterations. It is possible to identify some "black spots" at particular risk for the genesis of these accidents. The vehicles were rarely involved in single impacts, but more often in more than two sequential impacts. Complete destruction of the passenger compartment is shown in some cases. The narrow contact of deformed vehicles creates a dangerous situation in case of fire. Seat belts should be very easy to unbuckle in order to prevent jailing in cars in the middle of a progressing accident. Both the prevalence and human cost of the very severe motorway accidents could be reduced: (1) by a correct real-time information system for drivers; (2) by a better separation of light and heavy vehicles; and (3) by a better control of truck speed.
Abstract