Things are not always as they seem. The reflection in the puddle gives the illusion of a narrow and precarious walkway.
When you are walking about, keep your eyes open for more. What more is in the puddle you're quick to walk around or jump over? Look at it from different angles. There will be something there, especially on a sunny day or when city lights illuminate the more.
Be sure the reflection is as sharp as it can be. Move around if you have to. Change the settings on your camera to allow for a greater depth of field to keep the reflection and its source in focus. Bump up your speed to avoid camera shake. Pull out the tripod if you must. Just do what you can to find that which hides behind the surface.