The paper narrates the purpose of the six Lane highway project linking between north and south zone of Bihar state with 9.759km long extradosed bridge crossing over gigantic River Ganga and necessity of adopting extradosed bridge concept for crossing the entire 9.759km width of River Ganga. Concept development for the entire extradosed bridge based on the navigational requirements as per IWAI (Inland Waterways Authority of India), site constraints and geological condition of the subsurface have been explained. As the project has been allocated in EPC (Engineering, Procurement & Construction) mode, development of structural scheme like bifurcation of the overall bridge into individual blocks, span configuration, type of connection between substructure and superstructure have been articulated. Also necessity to adopt well foundations; design basis development as per construction methodology; expansion joint with Needle Beam concept; deck segment section finalization have been explained. One of the most critical phase in the project is the junction development over main bridge. Which establishes the connection with the island by ramp structures in the midway of the Bridge. Another important fact that this junction needs to be developed without compromising the extradosed concept in junction location as well. The ramps in island are aligned parallel to flow of River Ganga as the island is occupied with agricultural farms and relatively dense habitation even though the island has no permanent bridging with either side banks of River except water transport. In the past during flood season also there was little possibility to rescue people on time. Now the proposed junction development allows platform to facilitate the locals as a rescue shelter as the ramp structures are proposed just above the High Flood Level. The paper Concludes with benefits and difficulties of extradosed concept being used in this project over traditional balanced cantilever bridges for widen decks to accommodate six lanes of vehicular traffic with both side footpaths for pedestrian traffic.

Extradosed Bridge; Well Foundations; Expansion Joint; Bihar.