Wind-Tunnel Investigation of Curved and Vertical Wind Barriers for a Train–Bridge System with CFD-Based Flow Analysis: Evaluation of Train Protection and Bridge Wind-Load Increase

Crosswind protection on high-speed railway bridges is important for train running safety; however, bridge-mounted wind barriers may also increase wind loads on the bridge deck and barrier-supporting structure. Previous studies have mainly evaluated wind-barrier performance according to reductions in train aerodynamic loads, whereas direct experimental quantification of the trade-off between train protection and bridge lateral load increase for different barrier geometries remains limited. This study compares vertical and curved wind barriers through wind-tunnel tests using a 1:30 sectional model of a train–bridge system at a reference wind speed of 10 m/s. Barrier porosities in the range of 20–50% and wind attack angles ranging from −6° to 6° were considered. Train-surface pressure distributions and static three-component aerodynamic coefficients of both the train and bridge were measured simultaneously. A lateral load benefit–penalty index was introduced based on the train lateral load-reduction ratio and the bridge lateral load-increase ratio to enable the relative comparison of the tested barrier configurations, while steady Reynolds-averaged Navier–Stokes simulations were used to interpret the underlying flow mechanisms. Both barriers reduced the aerodynamic loads on the train, but the vertical barrier provided stronger train-side shielding at the cost of a larger increase in bridge lateral load. At 30% porosity and a wind attack angle of 0°, the vertical barrier reduced the train side-force coefficient by 75.4% and increased the bridge side-force coefficient by 89.2%, whereas the corresponding values for the curved barrier were 57.6% and 39.4%, respectively. Within the tested ranges, the curved barrier consistently achieved higher index values because its flow-guiding effect reduced pressure concentration and limited the additional lateral load on the bridge. The vertical barrier is therefore more suitable when maximum train protection is the primary objective, whereas the curved barrier provides a better balance between train protection and bridge wind-load control.