When a bridge crossing a waterway or in ocean is partially or entirely submerged during a flood event or ocean wave, its deck may be subjected to significant hydrodynamic loading.According to the time-varying wave forces acting on the bridges for various submergences, wave force interference actions between twin decks bridges were investigated preliminarily based on section physical model tests.The load distribution acting on bridge were calculated and analyzed.The experimental results have been analyzed via dimensional analysis and relationships between time-averaged force coefficients (drag, lift.and moment coefficients), the Deck Froude number and geometrical parameters of the problem are discussed and compared against relevant literature.Due to the presence of a free surface, force coefficients can be either larger (by more than a factor of 2) or lower than the corresponding values of the unbounded domain.The experimental drag coefficients are then compared with the results obtained by the momentum equation.