**4. Bridges construction and materials**

Due the large number of variables on the conceptual design of a structure, there is no special formula for determining the best option of a bridge. Many variables come into play, from the experience of the engineers and architects, to the specific needs of the place, such as topography, soil characteristics and materials availability.

There are several models to describe the general process of design, built, operation and maintenance of a bridge in a general way. One of the most compact flowcharts was proposed by Addis [13], shown in **Figure 12**.

The process for any bridge design consists of input data, regulations, design process and results, explained as follows:

**Figure 12.** *Model of the bridge design process [13].*
