The composite box corresponds to a section of the Júcar viaduct in the Eje de la Manchuela. In section 1 of interconnection between the CM-3201 road and the A-31 highway, specifically the passage over the Júcar River itself, which for environmental reasons require a span of 50.00 meters without affecting the channel. The bridge has an 11.00 m wide carriageway, divided into two 3.50 m lanes, 1.50 m outer shoulder and 1.50 m inner shoulder. Also, 0.50 m are available on the edges to support vehicle containment barriers.
The composite section has a single span of 49.80 meters, being an isostatic structure, with a span between axes of 48.90 m, the rest of the bridge is resolved using precast prestressed concrete beams.
The bridge is solved as a composite structure with a 2.00 m deep steel box section, with dimensions of 4.00 m in the lower wing and 5.00 m between axes in the upper part, externally coinciding with the dimensions of the precast concrete box of the rest of the sections. In the open area of the deck box, joining the upper platforms, there is a bracing system in the form of St. Andrew crosses, this bracing plays a vital role during assembly operations solving the lateral buckling of the compressed cords of the metal wings. The bridge has transverse frames to collect the distortion of the box section by eccentric loads.
On this box section, there are concrete slabs 6 cm thick, on which the deck is concreted, thus constituting the composite section. Typology is a bi-supported isostatic bridge, with positive flexion along its entire length, built without climbing.