We are in a decade of great technological progress, catalyzed by the development of the computer, which supplies tools that were unthinkable in the past, in order to accelerate the pioneering of developments for the betterment of mankind. In the field of automotive safety, remarkable developments like AIR BAGS, and the anti-blocking breaking system, have complemented the safety brought by the safety belts. Automobiles are improving each year, in terms of comfort, aerodynamic profiles, more powerful and efficient engines, with less pollution, very high acceleration rates and sophisticated commands, as if they were destinated to run alone in perfect streets and highways. In everyday utilization, however, the scenario is completely different, full of risky situations, brought by high speed and a great number of other different causes. Among them, a dramatic situation has existed since the beginning of the automotive industry, in which the occupants of smaller vehicles are totally defenseless, cowardly trapped, waiting for the coming seconds, to be inexorably decapitated, like animals in a slaughter house. This is the case of the collision of cars against the rear of trucks, when not equipped with reliable underride guards. In these cases, all the above mentioned safety devices are useless.This situation is particularly serious in Brazil, since there is no legislation that could make compulsory the installation of reliable guards, by lack of technical projects that could be applied to the great diversification of truck types. As an aggravating factor, there are no official statistics to precisely identify this kind of accident, but it is a well known fact that Brazil is the world champion of accidents in the transit. Some officials however estimate that underride collisions happen every day on the state roads only, and that 90% of the victims die or are severely mutilated, which makes the scenario for all the roads and streets very frightening. How many persons are decapitated per day?