[collyw]

Yes, but public transport is going to have to cope with elastic demand, so you can't base carriage sizes on the average number of passengers.

Here in Barcelona, it seems that the metro starts off quiet at the ends of the line (easy to get a seat), then as you approach the city centre it fills up (difficult to get a seat near these stations). Then it starts to empty on the way back out.

Electric bikes makes sense though.