Saturday, February 7, 2009

Lying for Mother Earth

For various reasons, I ride the bus and/or my bike to work most of the time. The idea is actually to phase out the bus and ride just my bike sometime this spring, but it's still a little cool and wet for that just now.

The university where I work is part of a county-wide campaign to reduce single-passenger cars on the roads (largely in the name of going green), and so we're all encouraged to log our trips to/from work with Pierce Trips Commute Calendar, apparently a county-run logger to track one's travels in non-single-driver commutes. This calendar makes some calculations of how much gas, money, and emissions you save over 'if you had driven alone.' There are incentives and prizes given out, both by the school and the county based on people's participation in the program. HR encourages the use of the calendar, which is fine by me.

I started using the calendar sometime in November.

You can actually see their calculations on a "Results" page, so every once in a while I take a look. I'm always struck by the patent dishonesty of their calculations. Here are my results as of today:


You've entered 32 trips since November 19, 2008
You eliminated 659.2 drive-alone miles.

You prevented the following from being emitted into the environment*:
535.78 pounds of carbon dioxide (contributes to global warming)
1.97 pounds of hydrocarbons (contributes to smog)
18 pounds of carbon monoxide (poisonous gas)

You saved 27.49 gallons of gasoline and $116.83 dollars*.

*Statistics based on average emissions for passenger cars and average gas price of $4.25.


So let's examine these numbers.


  1. Not every trip has been correctly entered, as I occasionally forget to do so until after I have forgotten details. So I probably actually saved a good deal more. But that's not the calendar's fault.

  2. The mileage is correct, according to Google Maps. Actually, my bike rides are longer than my bus and car rides (the direct route is not safe on a bike), but I log them as the same distance, because it's how many miles I saved, not how many I rode. So I've "saved" 659.2 miles.

  3. They calculate I've saved $116.83 dollars (sic). Let's ignore the redundancy for now, and examine this number. It's "based on... average gas price of $4.25". Gas hasn't cost $4.25/gallon since long before November 2008. It hung around $1.70/gallon for several weeks, and is now somewhere less than $2.50/gallon. So they're basing the calculation on some fantasy gas price.

  4. The "savings" in gas are based on $4.25/gal * 27.49 gal = $116.83. My calculator agrees with them, although as we've already seen, the actual average gas price is about half the number they calculate. But let's not be hasty: bus fare is $1.75/trip. So those 32 trips theoretically cost me 32 * $1.75 = $56.00. So when I subtract my bus fare, I actually "saved" only $60.83. Hmmm... not such a great savings. And if we correct for a more realistic gas price, it looks like I actually only came out ahead about $12.73.

  5. I have a bus pass, which lists at $63 / month. That's cheaper than paying regular fare, but it still means I paid (theoritically) $189 for November--January. So I'm actually coming out $72.17 behind for those three months.

  6. The $12.73 I saved (correcting for bus fare) aren't that impressive, given my commute time is about 25 minutes one-way in my car to work. But the bus trip takes me about 1:15 hours, so I take about 50 minutes longer one way to get to work. On 32 trips, that's 1600 minutes, or 27:40 hours. So I saved $12.73 in exchange for 27:40 hours. That means my time is valued at about $0.50/hr.

  7. I notice the emissions calculation also ignores the emissions the city bus makes in taking me to work, which entails at least one stop and subsequent restart specifically for me each way. The bus burns a great deal more fuel than my car, and emits a great deal more nasty stuff too. I don't have any real numbers for that, but I suspect it's at least 10-25% lower than they glowingly report, once it's amortized across all the bus riders (I've frequently been one of three passengers on a bus).



So they're pretty much lying to me about my "achievement".

The situation's not quite so dim as they raw numbers indicate. I get a serious discount on a monthly bus pass as a perk of working on campus, so I pay much less than $1.75 fare. And my car's a Suburban, so I burn more gas than they think. And honestly, I've used pretty rough numbers here. Not all my "saving" rides are on the bus: some are on my bike, which has no fare. And neither the calendar nor I have amortized vehicle maintenance over those trips. Of course, we'd need to amortize bike maintenance costs too.

But the point is, they don't actually know that. This is not my employer's project, it's a county project: not everyone on it gets discounted bus passes, not everyone drives an enormous beast when they do drive. And the gas price "estimates" are blatantly dishonest.

I intend to continue to ride my bike and/or the bus to work for reasons of my own. Not because of global warming (anthropogenic global warming is a political myth), but for reasons like a general disapproval of wastefulness and the fact that every mile I bike is a little less Ox.

But I thought it interesting how disingenuous this particular [county] government project is.

2 comments:

Ames said...

Did you factor in all the money you are saving on entertainment now that you can just watch school bus drivers making pit stops?

David said...

Just an FYI. The buses are all using Compressed Natural Gas (CNG) now so the emissions levels are drastically lower compared to "regular" buses and probably even most cars.
http://www.piercetransit.org/cng.htm