There’s a balance to be made between the flow of people and the seating capacity of trains.
Single level with many doors will load/unload quickly, however there’s barely any seating.
Two level maximizes seating at the expense of dwell times.
Nobody made a two level train with a focus on standing yet, so we don’t have a real world example. If it’s even possible because you need more headroom than usually available on double deckers
That said there are metro-like systems with double deckers. Paris and Sydney have already been mentioned. True, they are usually classified as suburban systems, but are very much used for city trips as well.
There’s a balance to be made between the flow of people and the seating capacity of trains.
Single level with many doors will load/unload quickly, however there’s barely any seating. Two level maximizes seating at the expense of dwell times.
Nobody made a two level train with a focus on standing yet, so we don’t have a real world example. If it’s even possible because you need more headroom than usually available on double deckers
That said there are metro-like systems with double deckers. Paris and Sydney have already been mentioned. True, they are usually classified as suburban systems, but are very much used for city trips as well.