In the representation of knowledge can not miss all those geometric, static, functional, and specialized notions in infrastructures that characterize the shape of a Civil Engineer. We take this opportunity to show how complex the representation of a hydraulic overflow, how bold is the company wanting to bring the cross sections, the view from above, the longitudinal section. And, yet how essential is the knowledge of descriptive geometry to determine the intersections of complex surfaces, the application of engineering has great feedback. An engineer must know how to read and know how to make a drawing, must learn to identify the main characteristics, must be able to focus on the goals and be able to identify the reading of the representation of another author. An engineer must be able to express in terms of own project idea without has any limits of freedom of thought. Sometimes, in fact, a drawing doesn’t have the fundamental informations about the representation and that is the limit of the project. This study intends to show some drawings of civil works project requiring the knowledge and understanding of the fundamentals of descriptive geometry, without which the expressive potential of the author would inevitably be compromised.