The research program will carry out CFD and wind tunnel tests of the stability and buffet response of flexibly-mounted bridge deck models. The bridge decks will be fitted with aerodynamic control surfaces of the oscillating flap type. A combination of sensors on the deck, a digital control system and electrical actuation of the flaps will be used to increase the bridge stability in the heave-torsion mode. Quasi-three-dimensional CFD will be used first to compute flutter boundaries. The critical wind speed for flutter onset will be evaluated from the responses at different subcritical wind speeds. The system response to indicial control-surface movement will also be computed and the results used to model bridges, first on a section of the deck and later on a three-dimensional model of a full bridge. Measurements will be made, for a range of bridge parameters including deck geometry and smooth/turbulent incident winds, to assess the effectiveness of the system in increasing critical flutter speeds and alleviating buffeting and vortex-induced-vibration for full scale suspension and cable-stayed bridges. These tests will also be used to validate the numerical results.