Usually when on a very long journey, one may have the urge to
respond to his/her natural calls.
And so there are toilets available on board a transportation
device.
Usually on board trains toilets could be found at each end of
passenger cars, expect on some types of cars such as the buffet
coach, and commuter trains i.e. MRT.
Waste generated by passengers on board were usually cleared away
directly onto the tracks as the trains move at high speeds. This
could let to incidents where careless passengers dropped their
valuables accidentally onto the tracks through the toilet!
However, trains of modern design usually contains waste in a
specially designed tank, to be emptied after the train has returned
back to the depot. This is usually found on high speed trains such
as Japanese Shinkansen.
As for buses, toilets could be found at the rear of an older design
long distance bus, and maybe into the tank, to be cleared once the
bus is at the depot/terminus.
But nowadays most of the newer long distance buses had eliminated
toilets from the design, and new buses such as those of Transtar
(SG-M'sia) would allocate scheduled toilet breaks for passengers at
a fixed location. (The back of the bus would instead be the galley
and the place for the assitant driver to take his break.)
As for ships, toilets could be found virtually everywhere except
onboard bumboats, and may be either to the tanks or directly to the
sea.
Finally, on board airplanes, toilets are found in the middle and
the rear parts of the plane, and would usually flow into a special
tank inside the aircraft.
