*3.3.1 Mexicali bridges: solution of the road distributor*

The Mexicali road distributor consists of a series of bridges connecting the main roads with the purpose of traffic flow continuity. Basically consists of two reinforced concrete bridges as underpass section and two structural steel bridges as overpass section. This structure is shown in **Figure 8**.

The underpass bridge section, both for vehicular and a railway line, consists of a reinforced concrete slab supported at the ends by retaining walls and circular columns of reinforced concrete supporting the center of the span. The main structure of this bridge section works as continuous girder. The spans are relatively short and the structural slab depth is enough to fulfill the flexure stresses requirements.

The structure also has two structural steel decks as an overpass bridges, consisting of continuous girder and supported by steel columns. The length of the spans is small since they do not exceed 165 feet (50 m). A particular feature of this particular structure is the energy dissipation device located below the girder supports. Mexicali has high seismic activity and the structure needs to withstand the seismic loads with good lateral displacement performance.
