June 05, 2003

Street Level Bus Exhaust

Category: Transit

London: Busses may emit less pollution per person than a normal car, but if you've ever been behind one, you may have noticed a rather impressive plume of black smoke most of the time. To alleviate this problem, most city busses have their exhaust pipes extended so the smoke belches out as high above street level as possible.

For some reason, the tallest busses in the world (London's Double Deckers), send their smoke out directly at street level, making life on the sidewalk utterly miserable at times. It's even worse if you're on a bike or motorcycle right behind one. How difficult would it be to just slap a 10ft piece of piping on the back to send the smoke up?

Posted by Nick at June 5, 2003 10:11 AM | TrackBack


But surely having the exhaust pipe high up means that the exhaust be sprayed over a larger area, including cars, cyclists and people on the pavement. Do exhaust fumes rise or sink - given that they are full of tiny particles, I'm thinking that they sink?

More important to a cyclist like myself, is the side and direction of the pipe. I'd prefer it on the floor, to the right hand side of the vehicle and pointing into the middle of the road - not the pavement.

Posted by: tom on June 8, 2003 01:25 PM

I'm pretty sure it all (at least until a good rain) goes straight up, hence smog.

I've noticed this myself while living in San Francisco. When riding right behing a regular Diesel powered Muni Bus, there's almost no trace of exhaust to bother you. (the pipe is on top of the bus)

But behind one of the Tourist Busses that clog market street, you can barely breath as the exhaust comes straight out the bottom.

Posted by: Nick on June 8, 2003 07:34 PM

"Do exhaust fumes rise or sink - given that they are full of tiny particles, I'm thinking that they sink?"

I'd say bits rise and bits float around and some bits sink - fumes being a mix of various things. some are best kept at as low a level as possible

not sure it's a good idea to throw particulates into the air at a height that will allow them to be spread over a wider area at a breathable height.

rather than displacing the emissions it's surely a better idea to reduce them.

(and they're not strictly the worlds tallest buses - some triple deckers have been made for the next Harry Potter film)

Posted by: JohnH on June 9, 2003 01:52 PM
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