To whet your appetite and keep your writing fingers limber, take a good look at the photo, or let a prompt settle in your mind. Set a timer for a reasonable amount of time, be that five, fifteen, or thirty minutes. Then start writing.
Write about a bus that moves too fast for people to see clearly. How does it work? Whom does it serve? Or tell the story of an unfortunate traveler who gets on the wrong bus that turns out to be the right one.
Write about a time when you traveled at night. How did it feel to be in one location when the sun went down and in another when it came up the next day?
Write a humorous post or article about a ill-fated trip you took and lessons you learned.