Five Percent: Conserve Energy

Climate Change Is Important: Energy Conservation is the First Step


November 25, 2007

Save Gasoline with E-Z Pass Electronic Toll Collection

The E-Z Pass electronic toll collection tag saved gasoline on our trip home this Thanksgiving. That’s my claim, and I’m sticking to it. The first way E-Z Pass saves gas is that you don’t have to bring your car to a complete stop and then accelerate back to highway speed. But based on my prior Thanksgiving driving trips I think there is a potentially much larger savings. In the past, we have waited in long toll lines during peak traffic hours. During this time, the car is idling; idling cars waste, not save gasoline.

Electronic toll collection systems potentially reduce idling in several ways:

  1. Cars with E-Z Pass sometimes don’t have to stop at all
  2. Cars without electronic tags wait a shorter time to pay since there are fewer cars who require manual toll collection
  3. Reduction of delay and ease of use may encourage more cars to substitute efficient and faster highway trips for side roads, e.g. during commuting

In my first long trip with my new transponder and lots of tolls, I have to say, E-Z Pass rocks! Whether my claims of environmental benefit are true, that’s harder to determine.

As with all such claims, this one is arguable. The first argument is that the transit authorities will use the opportunity to employ fewer toll collectors. The second is that the lack of traffic will encourage more people to choose driving a car over other choices. Another I hadn’t considered until I looked around: the ubiquitous adoption of systems like EZ Pass may allow highway authorities to raise toll rates more easily. (This last one could go either way: on the one hand, higher prices tend to reduce demand; on the other, the hypothesis is that decreased transparency of toll rates afforded by EZ pass is what makes raising rates possible; if people are not as aware that they are paying more for tolls, then presumably behavior will not change.)

I found a lot of hypothetical studies claiming the main benefit of reduced fuel consumption, e.g. from a paper called The Open Road

Tollbooth bottlenecks also increase fuel consumption. Studies
suggest that if a car were engaged in the toll collection process
for an hour, it would burn an extra half-gallon of fuel.9 This extra
combustion, in turn, produces greater amounts of carbon
dioxide, which contributes to global warming.

I wasn’t able to find any real studies that measure the actual benefit. This is probably because I didn’t look hard enough, but also possibly because actually measuring this would be quite a feat. A “before and after” study is impractical since adoption of the transponders takes a long time (it took me until last month, and Massachusetts’ FastLane has been around for many years now). Adoption may not be balanced; for example, perhaps people that use E-Z Pass are more likely to have newer cars, or older, or bigger? Overall trends in driving, commutation, energy costs and so on would have to be considered. Oh, and one more: if more people are driving hybrids, the gas engine turns off automatically — long toll lines are a perfect opportunity for this feature of hybrids to kick in. Such a study would be expensive. And in the end, I guess most people are content with the “common sense” result, which is free, if prone to error.

I’ll have to consider whether my current commute would be shorter or faster via the Mass Turnpike, versus my current very stop-and-go route.

If you do get an E-Z Pass, you can feel like you are doing a god thing for the environment, but only if you don’t use it as an excuse to drive more.

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