Long Bien Bridge (LBB) built between 1899 and 1902, is the iconic bridge of Hanoi. The bridge’s length is 2 290 meters across the Red River and, due to History, only some parts of the original structure remain intact, while large sections have been built later to repair the holes and destroyed parts. To ensure the safety and durability of the bridge, it is necessary to have a complete diagnostic of the structure under various loadings, with a distribution of the stresses in the load-carrying components. This is why Cetim and HUCE modelled numerically the first six spans of LBB, on Hanoi city side, for simulating the mechanical behavior, supporting the existing plans for maintenance and being a guideline of the project for complete renovation of LBB. A campaign of geometric measurement was necessary to recalibrate the theoretical modelling based on drawings and the various degradations (loss of thickness due to corrosion, holes…) and modifications (repairs, replacement of structural components…) were also considered. The final evaluation of RLA required the iterative analysis of the archives data collected concerning the different traffic histories of the bridge (trains, trucks, …) to the relevant load cases and load combinations.