Padma Multipurpose Bridge Project

Major Negative Impacts23. The potential negative impacts from main bridge construction activities are on: Transport (Road and Water) Charland/Bed Material Fisheries/ Aquatic Life Other Endangered Species Surface Water Quality Noise Quality and vibration24. Transport: About 162,624 tons (42 nos. footings each with 8nos.@3m diameter steel tubular pileswith 103m length) of 336 number of piles, about 267,000m 3 concrete pilecaps, piers, and concrete topslab, about 84,400 tons of fabricated steel truss, 4,300 nos 1.2m diameter bored piles for approachviaduct, and 168 bridge bearings will be required for the main bridge (including viaducts) construction.Detailed quantities of materials as per bridge components are provided in Table 7-7. Procurement ofmaterials from both overseas and within the country requires careful consideration by the contract.Jamuna Bridge experience in RTW is explained in Section 7.2.2.2. There are major traffic safety andrisks involved for procuring and transporting materials. In addition, all contractors are encouraged toverify suppliers’ eligibility and environmental permits prior to sign any suppliers’ agreements. Largequantities of materials will be transported by water transport, some of the material will be transportedby train and land transport. These additional transports will cause traffic congestion on the existingtransportation system. In addition, the local roads are not designed to these heavy axle loads and assuch may suffer damage from being used by these heavy transports.Table 7-7: Quantities of materials for major components of the bridgeComponent Material Unit QuantityBridgePiling (3m dia tubular piles) Supply ton 163,000Installation No 336Pilecaps Concrete m 3 80,000Reinforcement ton 12,000Piers Concrete m 3 11,000Reinforcement ton 1,600Superstructure Fabricated steel truss ton 84,000Concrete top slab m 3 72,000Approach ViaductsPiles 1.2m dia bored piles m 4,300Piers, pilecaps, headstocks Concrete m 3 90,000Reinforcement ton 13,500Superstructures Deck Concrete m 3 14,000Reinforcement ton 2,500Source: Consultant Scheme Design Report, 2009.25. Charland/Riverbed Material: Dredging will be done by the Main Bridge contractor to facilitateactivities (through Charland and other sections of the bridge alignment where the water depth will beshallow) and will depend on: The draft and maneuvering areas required for the vessels foro Piling (336 nos) activities at each pier locationo Pile caps and pier stem constructiono Erection of complete 150m length truss units (barges, possibly floating crane/s, etc.)o Possible delivery and erection of precast concrete upper bridge deck units, etc. The number of monsoon season cycles (assumed to be 3) encompassed by the aboveactivities, which would require substantial “re-dredging” of temporary channels after infillingduring the monsoon26. A reasonable estimate for each of the probable 3 years/post monsoon seasons would be asfollows: Access/transit channels with at least 100m base-width (at say -5m PWD) and with 5H:1V sidebatters7-11