Flash charging is also a concept of electrification where the technology enables charging within 20 seconds only. The method supports the use of smaller bus batteries as compared to any pure depot and occasional charging. The method is ideal for high bus frequency routes and for high passenger volumes without long bus downtimes.
During rush hours on main lines or an alternative which is cheaper than trams. The flash charging method is with strengths. The charging of the traction battery is per charge with enough energy to drive one to three kilometers where even in winter it is running with complete electric heating.
Sources:- All-electronics