Wind tunnel tests and analyses of the response of the Seo Hae Grand Bridge were conducted using section model technique. A 1/80 scale section model were used to develop the optimum section to minimize vortex shedding induced vibration without reducing the flutter speed. The final configuration was comprised of a combination of the replacement of the "New Jersey Barrier" with a railing type traffic barrier and "Flow Reattachment Vanes" at the upper and lower edge surfaces of the deck and main girder. In order to evaluate the sensitivity of the response to changes in structural damping, a series of tests were conducted with three different values of structural damping ranging from 0.2% to 1.0% of critical. Several options to increase the critical wind speed for torsional flutter were described and solutions proposed.