On the bus because the bus isn't a fixed place
When it's an airbus!When it Turns in to a street!
buc coupler is division between sections, for example if you have a line up of 10 panels, and it is divided into sections, so for mentnance purpose you won't required to shut down the whole up, if...
it is the tie of bus
The drivers have remote key to open the bus door even if they dont have any key at all.