Where I went to school (in the countryside), most children (who didn't walk or get dropped off by parents) went on dedicated school buses. By which I mean vehicles contracted by the county council specifically for the school, once in the morning and in the other direction in the afternoon (and they were generally coaches, not buses!). There were also a number of public bus routes which served the school. On most of these, all that happened was the most appropriately-timed bus in the timetable took a small diversion to the school; one one route, an additional bus was put on (marked in the timetable as school days only) at the relevant time, as otherwise the volume of children would overwhelm* the "standard hour" bus; this additional bus was, however, open to the public.
*The extra bus put on ran about 20 minutes after the "standard" one, and had a different route. Normally, when in the sixth form, I took the earlier bus. One day, this had some sort of mechanical failure, which I noticed* at the start of the last village; the driver ignored it, until everyone had been picked up from the various stops, and continued until reaching a suitable layby on the main road, whereupon he promptly pulled in, shut down, and said "it's broken". Cue excited chatter on board, "how many lessons will we miss" etc. As I expected, following a few phone calls, the extra bus pulled into the layby once it had picked up everyone as normal, and we all piled onto it. The broken down bus was an Enviro 300, the new one was an Enviro 200 MMC (apologies if this isn't the correct terminology, buses aren't my speciality!). I deliberately made sure I was the last person to board; this was almost impossible, as there physically wasn't room for anyone else. All seats filled, the aisles and luggage area full and standing (and squashed), right up to me being pressed up against the doors. I think I counted about 65 people in total; I can't remember exactly what the rating of the bus was, but it was definitely less than that! Fortunately, there were few "normals" on board. (This is because this bus service is almost exclusively used by pensioners on their free passes, and any regular passengers know that it's best to avoid the school time buses. I don't think I've ever seen more than about 5 passengers on board at any one time anyway!) For context, this is an hourly service between two towns, calling at lots of villages in between (but not always the same ones) operated by a local bus company using (unless one's out of action for maintenance) the same three vehicles and a pool of 4 or 5 regular drivers who know many of the passengers by name.
*I say noticed, I heard a beeping start in the cab, and thought "that doesn't sound good"!
