Supply And Assembly Of 72.00 Ml., Of Retaining Metallic Level H2, Work Width W5, Severity Class B And Dynamic Deflection 1.1, On Ends Of Slab In Reinforced Concrete, 36.00 X 8.30 M2., Of Variable Singing, In Existing Bridge Board Over The Izana River, In P.K.: 4+940 Of The Cp. So-P- 4189, In Two Sections Of 36.00 Ml