A lengthy search with Google has found a paucity of research regarding the environmental impact of cars vs. buses. The following undated article is one that provides some statistics. It was cited by another author in 2001. I think the lack of research in this area points to the biases by academia toward mass transit. If people can point me to other sources I'll post them.
This statement in the Corson article is telling.
A bus with as few as seven passengers is more fuel efficient than the average automobile used for commuting.
If we take this as something of a fact (and I am very willing to have better and newer research shown to me) than any bus with under 7 passengers automatically becomes less efficient. Busses with more than 7 passengers are potentially environmentally more friendly, but that is reduced each time any of those passengers is transported a greater distance than they would have driven (which is very likely with circuitous bus routes).
But even more important is the nitrogen oxides. A fully loaded bus emits 1.54 grams per passenger mile (g/pm). A car with one occupant emits 2.06 g/pm. If we assume that the bus holds 60 people, the totals grams emitted by the bus would be 92.4. Under this calculation, any time the occupancy of the bus drops below 45 passengers, it becomes more polluting than a single passenger car. The EPA can tell you how awful nitrogen oxides are. If you stand next to a bus, you can find out for yourself.
Utopians have a vision of everyone driving the bus to work together and saving Mother Earth. Ms. Corson says so herself in her article:
Obviously, if the majority of people used a public transport system instead of private vehicles, there would be less pollution produced.
The cold reality is that most people want to drive and are going to continue to drive. So our bus system should be based on that fact. By basing it on the wishful thinking of mass transit junkies, the MTD is almost certainly pouring more pollutants into our local environment than if they would merely confine themselves to areas that really need service.
The fuel effieciency of a bus with 7 passengers vs a private vehicle with 1 passenger speaks, I think, to the efficiency of moving people, not burning fuel.
I think the correct comparison should be not "passenger miles" but cubic feet (or some other measure) of polutants expelled.
One bus is better than 8 cars, equal to 7 cars, and worse than 6 cars? That kind of "science" is pretty flimsy.
What if you put 7 people in a 2005 van? Then which is more polluting?
Are all the cars 1968 Olds 98s? Or are they all Prius gas/electric hybrids? Or some average? Is the average from today, or years ago?
All I know, personally, is those buses belch a whole lot of black deisel smoke. And they tear up the roads. And they block traffic, meaning many vehicles are idling behind the bus, stop after stop after stop.
Does the study include everything attendant with MV operation, or just fuel efficiency?
What about the cost of the driver, paying Bill Volk's salary, covering the MTD board trips to Europe? Fuel efficiencey can't be the only thing in the cost analysis. Besides, I bet that study was done at fuel price of $1.35 per gallon, not the $2.50 that the price of diesel is now.
By the way, why isn't the MTD using renewable fuels? Should all of their buses be using home grown soy-diesel instead of supporting terroist states overseas with Bush's oil imports?
Wait, maybe the MTD board should fly to South America to look at Brazilian farmers and perhaps there is a trolly to look at there also.
In their defense, I think the MTD is using soy based diesel. But that still emits more particulate matter into the air. Diesel is much worse than car pollution.
What the MTD should do is studies on decreasing routes where the environmental impact is negative, which would certainly be over half of Champaign.
Funny, I didn't have much trouble finding articles. Here's about 4,000 for you. I guess academia isn't biased toward mass transit, after all. There are entire academic journals dedicated to the subject.
I also found a bunch through an engineering indexing serve, but I can't link to it here. Here's one interesting article:
The simulation results show that substitution of bus for car travel generally decreases the overall costs, particularly the costs of congestion, but increases exhaust emission costs if bus load factors are insufficiently high... In terms of the overall costs, increasing bus load factors by relatively modest amounts can lead to substantial reductions in these overall costs.
The paper you linked to is hardly scientific: there are no citations except in a general sense, the terms aren't well-defined, and there's no way to determine where she's getting her numbers.
I think your analysis of NOx emissions is a bit simplistic as well. I'll grant that NOx emission is probably higher in buses than cars, I think because they use diesel, and not gasoline which must have a lower nitrogen content. But it's not going to scale linearly as you assumed.
To use an economic analogy, buses have a higer fixed cost (in terms of pollution) and a lower marginal cost. That is, there's probably some value of emission that's constant and an additional term that increases with each passenger.
If you want to get real numbers that give you any actual insight into the complicated reality of the situation, you're going to need a much more complicated analysis.
this is funny..
http://www.news-gazette.com/localnews/story.cfm?Number=18601
I was hoping someone would write in with more bad research. Summations that full buses use less energy than cars are obvious. The larger question is where is the break even point. You said that buses have a lower marginal cost. Agreed. Now we need to determine the marginal cost so as to determine the economic viability of any particular bus route.
The article you linked to doesn't do that. It spews the obvious, which is no help. Further, from what I can tell, most of the articles in your google search are from europe. Their emissions standards are different than ours so I think those studies have little benefit for our community.
I will accept your help to find an article that tells us the information necessary to determine the marginal cost of running buses.
And thank you for proving my point that apologists for the MTD don't need hard scientific evidence, just vague platitudes.
Of the first ten links provided by Narc, two are for Sydney, Australia, one is for belgium, four are for Britain, two are for south asia, one is for the United States. As far as I can tell in my reading of them so far, none address the actual pollution caused by the vehicles in question.
Coming up with 4000 google responses on a query doesn't prove anything. If you google bad research mass transit you get 5280
If you want a detailed survey of the literature, you need to talk to an environmental engineer or someone that knows about transportation. As my use of the above analogy shows, I don't even know the right technical jargon to frame a search correctly, let alone which are the correct databases to search.
Yes, Googling bad research mass transit gives you a lot of hits. But that's deliberately misleading because the bad research term is unquoted, and therefore meaningless. Googling "bad research" "mass transit" gives only 2 hits.
My point was that I couldn't find adequate information on this on the web. You, unfortunately, have been able to give me no more help. I guess I wonder just what the MTD board uses to determine environmental impact.
Any environmental engineers out there who can help?
Here is one:
http://dtea.ist.utl.pt/Papers/Seville2002_Simoes_Coelho_Silva_Farias.pdf
See Table 1.
Summary: buses have slightly higher NOx and much higher particulate emmissions, but vastly lower CO and VOC emisssions, as well as fuel consumed, all on a per-mile basis.
However, if MTD is using biodiesel, their emissions may be slightly different. The wikipedia article on biodiesel says that BD may have higher NOx emissions (scrubbable by a catalytic converter), lower particulates, and lower CO and CO2 than regular diesel.
Thanks for trying I guess. However, the study you show is from Lisbon, where I imagine some of the emissions standards are different.
More importantly, the premise here is the economy is Lisbon, a major city. I imagine that in Chicago, the buses overall have a less polluting effect.
Once again, for the third time, I would like something that would tell me the total emissions for a bus so that I could calculate the emissions per passenger mile. Until I get that, it will be impossible to determine the environmental impact of driving a bus through west Champaign with two passengers (although I have a pretty good guess it's not good.)
Until I get someone to show me otherwise, I'm going with the poorly sourced article I had which makes the break even point 7 passengers on a bus.
Any study about how much safer for the environment the MTD is needs to account for all the people they run over each year also.