Big holes

love the show and understand most of it and am now rewatching it so i can finish it ( the last episode was deleted from my tivo, little brothers, ). When Roger brings out Big O he makes a huge hole with the train carrier thing, what happens to the hole, i mean he brings it out almost every episode so where do the holes go and how does the city repair them,,,,, its a stupid ? and i know most animes dont have to explain everything but i always wondered, oh to any one who wonders if Roger should be with Dorthy or Angel i say Dorthy sure shes an android and looks like a teenager but its anime so who cares.