1. easy to make; easy to fit on well; most strong, stable; coz the entry of the well is round !
2. I will check it out by asking authority, if let me guess, go by stations per 1000 cars, car per 1000 population;
3. for a certain issue, if he says yes, most likely he is right, if he says no, then most likely he is wrong, try to convince him, if I could not, live with it
4. make it controllable simple, nothing as complex as it seems if you could break it down.