What You Call that Thing that is on top of the subway station were the whole dust and garbage is located on top of the train (where it passes through?????

Is that "Thing" on top of the station or on top of the train?

Actually in the middile of train and station

The thing you are referring to on top of a subway station where dust and garbage accumulate is called a platform or platform canopy. It is the area where passengers wait for the train to arrive and board. The accumulation of dust and garbage on top of the train is typically due to particles and debris being stirred up as the train passes through tunnels and stations. To find more information about this, you can perform an online search using terms like "subway station platform", "subway platform canopy", or "subway station train passage". This will provide you with images, articles, and resources that explain the structure and purpose of subway station platforms in more detail.