Buffeting forces on bridge decks are commonly modelled by Sears’ function. However, it is well known that Sears’ function is reliable only for very streamlined bridge deck sections and that a complete model would require a suitable formulation of buffeting forces in time domain. In this paper, self-excited and buffeting loads are modelled by means of indicial functions. Corresponding aerodynamic admittance functions are numerically evaluated for rectangular sections and compared with experimental and analytical results. A complete time-domain model for cross-sections including vertical turbulence is presented. Numerical simulations are performed on a sample rectangular section. Comparison with experimental results and relevant flutter analyses are also discussed.