7. Steel bridges

Thanks to constant progress in the manufacture of steels with high, consistent mechanical properties guaranteed by standards, improved assembly techniques, assembly methods and corrosion protection techniques, steel construction boasts undeniable advantages in terms of the material's excellent weight/performance ratio, the ability to manufacture parts in the workshop under optimum quality conditions, and rapid assembly processes. The gradual fall in the price of steel and the rise in labour costs have led engineers to simplify structural design as much as possible, and even to abandon certain types of structure. This strong tendency towards simplification has led bridge design to focus on composite structures, consisting of a reinforced concrete slab combined with two or more steel I-beams.