Commuting - Why do school buses exhaust out the back?

Most trucks and buses have exhausts that vent out the top or back but most school buses have this huge pipe that comes right out the back into your face. Most times I'd rather just push extra hard and pass them if they're going fast on an avenue or I'd just slow down and give myself about a block to avoid the fumes.

I'm going to take a guess here. Trucks, as in separate cab from the cargo area, have that separation, so they can run it up with no worries of the exhaust flowing into the cargo area. City buses have rear engine, so the exhaust can go straight up and without going through passenger area. Most school buses are still front engine. Just a guess on my part.

I can't see why they can't just run an elbow and have the pipe run up the side of the back of the bus. Or at least pipe the exhaust into the bus to sedate those noisy kids.

Total shot in the dark here, but I would say it's a contact hazard. Kids are dumb enough to touch something like that on the side of the bus so they route it under and all the way back to remove the temptation.

Makes it easier to stuff tomatoes in.

Yeah, exhaust out the back to clear passenger area.

Here's an old one........
Confusious say, " Man who ride behind bus get exhausted."

That's potatoes, not tomatoes!

..... Because if it ran inside little Johhny would do even worse on tests!

Total shot in the dark here, but I would say it's a contact hazard. Kids are dumb enough to touch something like that on the side of the bus so they route it under and all the way back to remove the temptation.

Yeah but it'll be routed up the side in the back on the OUTSIDE of the bus...

Some of our buses here are rear-engined and they still have bottom/back exit exhausts, which doesn't really make any sense. Same engine configuration as a standard city bus, different exhaust routing. However, a front engined bus has to have the exhaust come straight back under the chassis out the back. Well, unless it's like some dumptrucks and exits downwards halfway back.

I know the rule for regular vehicles (so I would assume it's true for large vehicles as well) is that the exhaust must exit BEHIND the passenger area (to reduce the amount getting sucked into the passenger compartment). So it's OK for trucks to have it dump out before the bed, but buses must have exhaust that exits at the back of the vehicle.

After that it's primarily what's easiest to route the pipe. It's pretty easy to route it straight back down the underside of the vehicle. Front-engine school buses are basically just regular trucks/vans scaled up in size.

I strongly suspect that city buses are subject to more regulations regarding emissions, noise, etc. than school buses. It is amazing how many special rules there are for different types of vehicle (logging trucks for example get to ignore almost every single safety requirement for their trailers).

I also suspect school buses are quite a bit cheaper than city buses. Every single rural county has to have at least a few school buses, but normally only fairly decent-sized cities have city buses. So school buses are probably designed on the easiest/cheapest rule.

No where to run the pipe. It's not safe to run through the passenger compartment.

That's potatoes, not tomatoes!

And it was proved false by the MythBusters.

as we all know busses are finely tuned performance machines. as such having a straight exhaust system out the back reduces resistance and allows the school bus to perform better in the quarter-mile. good for getting kids to school on time but bad for the bike commuter stuck behind them. :p

I knew it! Open exhausts.. that must be it. Now I know why my hair keeps getting singed when I draft the school bus.

Eggplant Jeff is correct; the opening of the tailpipe must be to the rear of the passenger compartmnent.

Eggplant Jeff is correct, thought to the rear and above would also work. The reason that the exhaust is routed as it is... The chassis, including all of the drivetrain, suspension, and exhaust is manufactured by a truck manufacturing company. It is then shipped to a coach maker, who puts the body on afterward. If the exhaust were bent up at the rear it would be much more likely to be damaged in transit as well as making it harder to place the completed body. Most of the major school bus coach makers are here in Indananner.

When we do get around to engineering less offensive public sector vehicles, can we also get the garbage trucks to route their pleasing aromas above bicycular traffic?

Eggplant Jeff is correct, thought to the rear and above would also work. The reason that the exhaust is routed as it is... The chassis, including all of the drivetrain, suspension, and exhaust is manufactured by a truck manufacturing company. It is then shipped to a coach maker, who puts the body on afterward. If the exhaust were bent up at the rear it would be much more likely to be damaged in transit as well as making it harder to place the completed body. Most of the major school bus coach makers are here in Indananner.

Not to mention that routing the exhaust up the back would require additional tubing and would have to be shielded to prevent people from getting burns from contact with it.

Yeah but it'll be routed up the side in the back on the OUTSIDE of the bus...
Kids are dumb enough to touch anything on the outside of a bus. Especially approaching the bus after school when they have more time than in the mornings

I suspect it's a mix of cost and interior space.

See, for interior space, that pipe has to go somewhere, so there would have to be a channel inside the bus to route the pipe to the top...this would remove passenger space.

Cost because they cannot afford to lengthen the bus, since it adds unecessary cost, so the cheapest option is to just run it straight from the front to back. Bonus is less bends as well, which means the exhaust piping itself is cheaper as well.

Gotta keep in mind schoolbusses are built as cheaply as possible....also amazing how long those things last with how cheaply they are built.

When we do get around to engineering less offensive public sector vehicles, can we also get the garbage trucks to route their pleasing aromas above bicycular traffic?

Man, if someone could come up with a way to route the stench from one of those things they'd deserve a nobel prize. *L*

But then the old "what has four wheels and flies" joke would no longer be funny!

But then the old "what has four wheels and flies" joke would no longer be funny!

I don't know if you'd be able to blame that entirely on cleaning up the smell. :D

Kids are dumb enough to touch anything on the outside of a bus. Especially approaching the bus after school when they have more time than in the mornings

A "Do not touch" sign should take care of that nicely...

ROFL!!!

slvoid, if you think a "Do not touch" sign would keep kids from touching it, you haven't spent enough time with kids.

And the point is not to protect from legal liability, it is to not let the kids hurt themselves.

For any who are wondering, a city bus goes for about $350,000 for a regular bus or $450,000 for hybrid.

I can guarantee that school buses cost a whole lot less!

Then again, they cost that because they only sell 2000 of them across the whole country per year....

A single bus factory in Russia cranks out more than 5000 city buses annually...

For comparison, I saw in a news article just now that school buses cost $80-95,000.

....also amazing how long those things last with how cheaply they are built.

I expect they are subject to a much more intense maintenance schedule than many other vehicles.

They're also pretty darn simple. Very basic. No sophisticated hi-tech engine, no A/C (on most of them), not a lot of fancy do-dads to break.

I've ridden on buses where the exhaust system is pointed upward. It's not impossible but I'm sure it costs more. Unfortunately, buses with the exhaust pointed up are not all that perfect either. If the bus is dirty, the exhaust gets dumped about 15 feet in the air but comes right down creating a cloud of smoke that's almost as bad as if were pointed on the ground.

Bus Ex. (http://www.crh.noaa.gov/oax/archive/hallam/norrschool3.jpg)

Yes, it goes stright back, very simple, cheap, and smart.

GEEK