For this particular application, I wonder why we can't improve on a solution already employed in many cities, and that is add a small battery to an electric trolley bus (basically, a city bus with a trolley pole or pantograph)? Since buses tend to run on a fixed route, the overhead wires would provide the primary power, but if for some reason it needs to deviate (such as a blocked street) the driver can retract the trolley pole/pantograph and drive on batteries for a short distance until it can resume the fixed route again. Or a route can be devised that will allow the bus to use the overhead wires for most of its journey, but will use batteries for the part of it where there are no overhead wires; many bus routes in urban areas run along concurrent paths for part of their routes. The battery will be continuously charged by the overhead wires, so no need for a quick charge solution.
For other areas I wonder if a hybrid-electric solution would be more practical than trying to make a full on EV bus.
Blue Ocean 2012 Leaf SV, lost that 1st bar at 34 months/26,435 miles. Lease returned 2 months later. Final LeafStat figures: 225 Gids, 17.44 kWH, SOC 91.89%, SOH 82.36%, 69.49% HX, 54.57 Ahr, battery temp 61.8 F.
Now driving a 2015 VW eGolf SEL.