Study on flow structures affecting vehicle running stability on bridge deck under strong cross wind

Vehicle overturning accidents on a bridge often happen during strong crosswinds. In order to prevent such accidents, a bridge operator imposes some traffic regulations such as speed limit or bridge closure. Besides, safety measures such as a windshield are installed in some cases. In case of long-span bridges, a windshield is difficult to install for the entire span because it decreases aerodynamic stability. However, some recent bridges installed a windshield with keeping enough aerodynamic stability. In order to enhance vehicle running stability against strong crosswinds, in any case understanding of the flow structures on a bridge deck is necessary. Then, an optimum windshield having high aerodynamic performance can be developed. In this study, targeting typical bridge decks of truss and closed box, flow structures on the bridge decks are investigated by wind-tunnel experiment first. Then, optimum shape and dimensions of a windshield are investigated with respect to the reduction of crosswind on the bridge deck and wind-induced vibration. In addition, PIV tests are conducted to understand flow fields around the bridge deck.