>>1565991>>1566009https://en.wikipedia.org/wiki/Double-decker_bus#Comparison_with_articulated_busesOperators worldwide must often decide between articulated and double-decker buses on popular routes. Articulated buses, entirely on one level, offer more room for disabled passengers, luggage and pushchairs; they may also be needed on routes going under low bridges or weak bridges that cannot take high axle loads. Double-decker buses, however, have a smaller road footprint and as such disrupt traffic, or block turning lanes less than articulated buses.
Double-decker buses may be more popular with passengers because of the better view, and with cyclists, who may be at less risk than they are with the unpredictable swing of an articulated bus's tail. Articulated buses normally offer more standing room while double-decker buses may sometimes (not always) offer more seats. Articulated buses have less dwell time because of the extra doors, and double-decker buses offer fewer chances for fare dodgers since there are fewer or no unmanned doors.
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I think you can make the upper floor "fatter" than the lower one to have more room (adjusting the mass distribution properly for stability), and have more doors for boarding and unboarding if you change how people are charged for the trip.
Also using modern materials, structures, powertrains, drivetrains, ... can leave more room in the lower floor.
