I want to know when to use "pop up". Is "pop up" in this sentence the same as the word "pop-up" in "pop-up store"?
Good question! In this context, "pop up" means to suddenly appear or occur. The speaker is stating that the roadside clinics have "appeared suddenly." "Pop-up store" also holds a similar meaning - they appear suddenly and usually are not open for a long period of time. Ex. A hot dog stand popped up near my office. Ex. There is an empty space in the mall that is rented by pop-up stores.