Especially with a little bit of battery in the locomotive. A huge chunk of the expensive to string overhead wires for pantographs is bridges, tunnels, and other

Especially with a little bit of battery in the locomotive. A huge chunk of the expensive to string overhead wires for pantographs is bridges, tunnels, and other obstructions not sized for the space needed for the wires. If the train can supply some power to hop between some relatively small gaps suddenly the whole project is pretty affordable. Same thinking applies to trolly buses. If the bus can supply its own power through intersections and when moving between routes or just around the bus depot suddenly nearly all the logistical headaches of trolly buses go away and the same amount of battery that would get you 1 BEV bus gets you a whole fleet of trolley buses going all over the city.