Aghhh! Run for the hills! Something even more polluting than a Hummer!

[Mackenzie]

I guess I'm only supposed to post a brief excerpt, but you can click on the link if you want to read the rest of it. This is pretty scary stuff.

Any scientists or environmentalists or anyone else here who want to comment on this or offer any opinions?

http://www.lp.org/lpnews/0412/hummer.html

"The Colorado Railcar that Capital Metro is considering for use in the commuter rail plan may be clean compared to other trains, but is still extremely dirty," he said. "Even with a full passenger load, it emits more pollution per passenger mile than a Chevrolet H2 Hummer. "The Colorado Railcar will emit around .836 grams of NOx per passenger mile when fully loaded with 92 passengers. NOx is a smog precursor; when NOx and hydrocarbons cook in the summer afternoon sun they produce ozone and smog.

"By comparison, a Chevrolet H2 Hummer with a single occupant emits .7 grams of NOx per passenger mile. The H2 is classified by the EPA as a heavier truck and so has more lenient emission requirements" than other passenger vehicles.

By contrast, "a Chevrolet Suburban emits .15 grams of NOx per mile and a Honda Accord emits .03 grams per mile," Ravet added.

Besides the environmental impact, the proposed train wouldn't be a bargain monetarily, either.

"With a retail price of around $55,000 apiece, Capital Metro could buy each a brand-new, fully loaded H2 for slightly less than the cost of the rail construction," Ravet said.

[muriel_volestrangler]

1. Perhaps; it depends on the sort of pollution you're talking about

Diesel engines do produce more NOx than gasoline ones (though some say that as the gasoline engines age, they produce just as much as a diesel). The diesel is more efficient for CO2 pollution.

I'm not sure where the NOx figures came from for the Colorado Railcar; here are figures from a UK government source for the British equivalent - the 'Sprinter' train unit (slightly smaller - seats 56 people when full):
CO2 as carbon 467 g/km
NOx 22.1 g/km

I think 467 g of carbon comes from (roughly) 467 * 14 / 12 = 550 g of diesel (taking the chemical formula as roughly (CH2)n )
550 g of diesel at 827g/litre is 0.665 litres
0.665 litres/km is 0.665 * 1.6 / 3.785 = 0.28 US gallons/mile, or about 3.5 miles/gallon.
With 56 passengers, that's 200 passenger miles/gallon.

22.1 g/km is 22.1 * 1.6 = 35.4 g/mile, or 0.63 g/passenger mile of NOx.

So a full Sprinter unit would seem to have slightly less NOx emissions than a single-occupant H2; and get maybe 12 times better fuel economy (ie emit one twelfth of the CO2).

The Colorado Railcar only claims 2 miles/gallon, but seats 92, so the NOx and CO2 figures may be roughly equivalent.

The train will probably emit more NOx than 92 commuters using real cars, rather than scaled-up Tonka toys, but use less fuel.

Since I see from news reports that this uses existing rails, I'm surprised at the cost - $60 million.

[amandabeech]

2. The Colorado rail car is the lightest commuter rail

that can run on existing freight tracks without special scheduling to keep freight and long-distance passenger trains far away. That's because the Colorado car has passed certain FTC safety standards.

It makes a great deal of sense, then, to put these trains on existing tracks when at all possible, thus cutting down on capital costs. However, the article does not state whether the tracks are to be new or old, or whether new tracks will also accommodate freight.