Bus service is easy to introduce or modify: basic service requires only purchase of vehicles, garage
and maintenance facilities, and organization of service. Stops along the lines can be simple.
Therefore, buses represent the most economical transit mode for lightly traveled lines. This
flexibility of bus routes is an advantage for any necessary changes, but it is a disadvantage for major
bus lines: they lack permanence, efficiency in carrying heavy passenger volumes, and image of
permanent, physically fixed routes desired by passengers