## 2 Outline of the Experimental Procedure
### Section Model and Wind Velocity Measuring Points  
As shown in Figure 2, we used prototypes of the CRH380 HST and a blunt box girder bridge to conduct wind tunnel experiments. To avoid distortion of test results due to the Reynolds number effects, HST and bridge models were made at a large scale of 1:15. Under a uniform oncoming flow of 12 m/s, the model Reynolds number can reach 1.9 \(\times\) 10\({}^{5}\). At this time, the bridge model is 0.23 m high and 0.97 m wide, and the train model size is 0.233 m (height) \(\times\) 0.225 m (width). We set the measuring sections at 1/4, 1/2, and 3/4 of the model. Thirty measuring points were arranged for each train section, and 42 measuring points were arranged for each bridge section. To avoid the influence of distortion effects, the length of all pressure measurement tubes was set to 0.5 m. According to [PERSON] et al. [11], the aperture size of the wind barrier may affect the test results. Considering that the aperture of the wind barrier model will be smaller than 2 mm after being scaled proportionally, it will affect the formation of the jet through the pressure relief hole. Therefore, under the premise of ensuring the same area of the ventilation surface, the pressure relief holes on the barrier are enlarged and rearranged in the corresponding positions. The wind tunnel experiments were carried out in the high-speed test section of the wind tunnel laboratory at Central South University. The size of the test section is 15.0 m (length) \(\times\)3.0 m (width) \(\times\) 3.0 m (height). Considering the limitation of the maximum (max) blockage ratio of the wind tunnel experiment, the model length is defined as 2 m. The model is placed at a height of 1.6 m from the ground, and large end plates are placed on both sides to effectively avoid the interference of end effects and wind tunnel wall effects on the test results. All  
Figure 1: Design parameters of WGB. models are made of high-strength ABS sheets to ensure sufficient rigidity. The wind field test uses a mobile testing system independently developed by Central South University, which can accurately control the spatial position of the Cobra probe through the mobile measurement frame and self-developed control software. The wind velocity point layout scheme is shown in Figure 3, and a gradually denser layout is adopted from the top to the bottom. A total of 4 test surfaces and 44 wind velocity measurement points are arranged from the windward side to the leeward side of the track centerline. The sampling frequency of the Cobra probe manufactured and calibrated by Turbulent Flow Instruments (TFI) Company is set to 2048 Hz, and the sampling time was 20 s. Each measurement point collects 40,960 data points to ensure the reliability of wind velocity test results. Figure 3: Arrangement of wind velocity measuring points (unit: mm). Figure 2: Arrangements of pressure taps on the train and bridge cross-section (unit: mm). The following aspects will be tested in the experiments:  
(1) Pressure measurement on trains and bridges. The pressure distribution on the surfaces of trains and bridges under crosswind was tested using PSI pressure scanning valves placed inside the model. (2) Force measurement on bridges and wind barriers. Two ATI-type scales were installed on both sides of the model end plate to measure the aerodynamic forces of the bridge-barrier system. (3) Wind velocity measurements on the bridge deck. A mobile testing system developed by Central South University was used to test the wind velocity on the bridge deck using a Cobra probe. Considering the installation situation on the bridge in practical engineering, the effects of the upper width of the railing, the deflection angle of the secondary guide wind angle, the height of the barrier, the distance from the centerline of the track, and the installation spacing were only considered in this study under the conditions of \(B_{2}\) = 540 mm, \(\theta_{2}\) = 20\({}^{\circ}\), \(H\) = 3000 mm, \(D\) = 3200 mm, and \(D_{1}\) = 500 mm.