A tunnel is an unerground passage way. The definition of what constitutes a tunnel is not universally agreed upon. However, in general tunnels are at least twice as long as they are wide. In addition, they should be completely enclosed on all sides, save for the openings at each end. Some civic planners define a tunnel as 0.1 miles (0.16 kilometers) in length or longer, while anything shorter than this should be called a chute. For example, the underpass beneath Yahata Station in Kitakyushu, Japan is only 0.08 miles long and therefore should not be considered a tunnel.