Question: "Each time he made the turn, he saw only the white, unused, buckling sidewalk, with perhaps, on one night, something vanishing swiftly across a lawn"... p.11 Fahreheit 451

Does it mean that the sidewalk is bent (upward), as when a tree grows next to a sidewalk and distorts it to make room for its roots? But then again, it seems paradoxical that it's buckling but also unused... Any thoughts?

Answer: 
“Going on vacation” refers to the change of state from “not on vacation to “on vacation”, similar to a light bulb “going out” when we flip its switch.

This usage may have originated from the idea that people do often go *away* on their vacations, but it is not limited to that meaning today.
"On vacation" simply means "not at work" or "not in school", etc. - you're taking a break from your usual duties. If someone is on vacation now, it simply means they're taking time off. Some people travel for their vacations, but not everyone does - in fact, there's a colloquial term "staycation" for those who *stay* home rather than go somewhere else.

I agree with Kate Bunting that "going on vacation" may imply traveling, but in the end it really is a question for Susan ;)