MTR & Railways could potentially be targets for these kinds of Vertical Axis Wind Turbine. Like the application on roads and highways, when the train pass by it rotates the wind turbines. Compare with vehicles,  train speed  is more stable and expected to generate more power.

There are 3 sources of increased airspeed in the tunnels:

A. Natural Bernoulli effect, airspeed accelerates when the surface area decreases (tunnel).

B. Available ventilation systems in the tunnels.

C. Passing by trains inside the tunnels would certainly generate wind speed.