Roads - Geometry of roads

The article [C 4 308] highlights the predominance of road transport for both people and goods, not only in France, but in every country in the world.

Even if the gradual reduction in fossil fuel resources, coupled with growing concerns about the rising greenhouse gas content of the atmosphere, lead policy-makers to support the development of alternative solutions, roads will continue to be a major component of the world's transport systems for a long time to come.

It is therefore essential to obtain the best possible service from road networks, and to achieve this :

• make travel as comfortable as possible;

• reduce the dramatic and economically devastating consequences of road accidents;

• reduce the impact of road infrastructure and traffic on the environment.

The choice of appropriate geometric characteristics is one way of meeting all these objectives. This is the theme of the present article, which builds on the introductory elements of [C 4 308] , and will be supplemented by an article on road equipment, an essential accompaniment to the user's journey, to help him "understand the road" and alert him to any imperfections that site difficulties may impose on ideal geometry.