Let's say using 2 bendies (2x 18m = 36m) and 3 DDs (3x 12m =
36m), if we time each set individually offloading the same number
of pax each (say 80 for each DD and 120 for each bendy), bendies
take much faster to unload that 150% more pax and can close doors
faster than DDs which still require some pax to exit the flight of
stairs. Note that each type of buses are offloading 240 pax in
this case, and both types of buses have been added to reach 36m.
And we are assuming in this case that everyone is alighting.
Basically 80 pax leaving from that 2 exits (assuming you can use
entrance doors) while 120 pax leaving from 3 exits. Though it may
seem like bendies offloading more pax but eventually both types of
buses are offloading average 40 pax each from the individual
doors. However bendies don't need pax to climb down stairs so
they can directly get up from their seats and head for the exit
doors while in a DD, a noticeable fraction of pax still
need to go down the stairs.
So eventually what you get is that bendies shut their doors
faster and move off, while DDs are still struggling with that
last bit of pax.
So this is not about how long the buses are, even though yes it
may seem to hinder other vehicles, but how fast they can let
passengers off, because how long they stay in the bus bay depends
on how fast they let passengers off. Assuming the above situation
continues on, meaning at regular intervals 2 bendies and 3 DDs
arrive again, we find that this bus-blocking problem
exists in both cases, and not just bendies.
I full agree on this point, but however, what if the local bus
body makers who designed an ''imaginary DD'' which had 3 doors (2
rear doors and 1 entrance) and 2 stairways leading to the upper
deck? Would it make the rate of unloading a DD to be twice as
faster?