238 justifies for double decks. However, due to the number of
old folk using the service, it'd be very troublesome for them to
move around in a DD. On top of that, people usually go to the upper
deck for medium to long trips, or they cant find a place on the
lower deck.
As for your 231 thingy, the general public abide by this rule: take
the first bus that come. as long as i can reach my destination,
good enough.
