The hydraulic system consists of the regimentation and channeling of surface rain water.
Creating a new road often interferes with the rainwater runoff course, or with the free flow of watercourses, changing the natural balances. The main effect of rainwater on the roads is to erode and remove the ground, causing a gradual and continuous weakening of the area. Same erosive effect have the waters of the river or stream at the bottom of the riverbed on the walls. All this highlights both the importance of a correct sizing of the hydraulic works to protect the road structure from rain water, and the need of hydraulic analysis of watercourses affected by the construction of road infrastructure. In order to make the design of the structures, it is necessary to preliminarily determine the extent that such artifacts must be able to dissipate .
Contour ditches are modestly sized channels made in order to capture the surface runoff water before they can reach the location of the infrastructure. Typically the section of the contour ditch is trapezoidal, in the ground or coated. They are made almost longitudinal respect to the axis of the infrastructure immediately tread upstream of the works of the abutments. The flow of water in contour ditches is identified by the slope of the ditch which coincides with that of the ground where it is based and not necessarily that flow has the same direction of flow of the water gutter..
The major communication routes and highways need for the characteristics of speed allowed, the incursions of animal protection or anything else represents a risk to the safety of those traveling through. The safety nets fully solve the task. They are made with differentiated knit net one meter high and are usually accompanied by struts with U or T form placed at wheelbase of 2000mm and with bear tension wires and thorn rope at the top. Every 30 m bracing is used and every 90/100 m cornerstone struts are used.