• Full-scale experiments reveal two distinct peak pressure scenarios on PSDs in high-speed subway stations with middle air shafts: compression waves from trains traversing air shafts and direct train-induced flow when passing PSDs.
• Peak positive pressures from direct train passage significantly exceed those from compression waves, highlighting the dominant aerodynamic load mechanism.
• Closing the middle air shaft reduces passing pressure waves, while installing bypass ducts at overtaking station entrances mitigates peak negative pressures by up to 8%.
• These findings offer actionable insights for optimizing tunnel structural design to enhance safety and comfort in high-speed subway systems.