Bus time schedule database design
Since you really only have to keep track of times between stations on each route, you only need to keep the start time of each route, the rest can be calculated easily by storing the time delta value for each line stop (the time between the current station and the last station ), instead of keeping time data for each route_stop. You also need to maintain the order of the stops on the line, and if it's a circular route you simply put the stops twice into the chain with different ordering numbers ( so each stop on a circular route is inserted twice into the route_station relation table with different order number ).

You can of course keep the time for each stop if you want, but that seems redundant and makes it harder adding stops to a route, since you'd then have to recalculate all bus stop times, instead of simply adding the new stop and updating the delta time of the next stop.

I'd probably start with a data model like this ( but of course this needs to be expanded if you want to add information about the buses and drivers etc ) :

lines (id, name, ...)

routes (id, name, line_id, ...)

stops (id, location)

line_stops (id, line_id, stop_id, order, time_delta)

route_start_times (id, route_id, start_time)