Your Baby and EZ-Pass
Daniel Pink points me to an interesting new study via NBER: “Traffic Congestion and Infant Health: Evidence from E-ZPass,” by Janet Currie and Reed Walker.
The abstract states:
This paper provides evidence of the significant negative health externalities of traffic congestion. We exploit the introduction of electronic toll collection, or E-ZPass, which greatly reduced traffic congestion and emissions from motor vehicles in the vicinity of highway toll plazas. Specifically, we compare infants born to mothers living near toll plazas to infants born to mothers living near busy roadways but away from toll plazas with the idea that mothers living away from toll plazas did not experience significant reductions in local traffic congestion. We also examine differences in the health of infants born to the same mother, but who differ in terms of whether or not they were “exposed” to E-ZPass. We find that reductions in traffic congestion generated by E-ZPass reduced the incidence of prematurity and low birth weight among mothers within 2km of a toll plaza by 10.8% and 11.8% respectively. Estimates from mother fixed effects models are very similar. There were no immediate changes in the characteristics of mothers or in housing prices in the vicinity of toll plazas that could explain these changes, and the results are robust to many changes in specification. The results suggest that traffic congestion is a significant contributor to poor health in affected infants. Estimates of the costs of traffic congestion should account for these important health externalities.
I’ve not read the paper yet (if anyone has a PDF I’d love to see), but one interesting question is whether this is longitudinal as well — were the rates tracked before and after the introduction of EZ-Pass? And would this vary depending upon the number of lanes that actually offer EZ-Pass (roughly half at most NYC-area toll plazas). A provocative thesis in any case, coming on the heels of David Owens’ interesting piece in the WSJ.
Congestion isn’t an environmental problem; it’s a driving problem. If reducing it merely makes life easier for those who drive, then the improved traffic flow can actually increase the environmental damage done by cars, by raising overall traffic volume, encouraging sprawl and long car commutes. A popular effort to curb rush-hour congestion, freeway entrance ramp meters, is commonly seen as good for the environment. But they significantly decrease peak-period travel times—by 10% in Atlanta and 22% in Houston, according to studies in those cities—and lead to increases in overall vehicle volume. In Minnesota, ramp metering increased overall traffic volume by 9% and peak volume by 14%. The increase in traffic volume was accompanied by a corresponding increase in fuel consumption of 5.5 million gallons.
One thing I’d be curious to know about the papers Owens’ cites is whether the introduction of ramp metering simply brought more vehicles back to the metered-facility, and away from other roads they may have been traveling on (perhaps those were covered in the “overall vehicle volume,” but it typically seems smaller roads are not as well measured in those terms compared to highways).
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This entry was posted on Tuesday, October 13th, 2009 at 7:36 am and is filed under Congestion, Drivers, Environmental factors, Etc., Traffic safety. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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October 13th, 2009 at 10:20 am
I don’t see how reducing peak-period travel times and increasing traffic volumes are bad things? Ramp meters aren’t designed to curb rush-hour congestion. They are designed to control the flow of rush-hour congestion. Instead of five, six or ten vehicles entering the highway in one big block and causing congestion around the on-ramp, vehicles enter the highway at a metered interval, reducing congestion.
I agree with your last paragraph. The whole “fuel consumption of 5.5 million gallons” is meaningless without something to compare it to. What if those same people in Minnesota used local roads and consumed, 6.5 million gallons? That would be a reduction of 1 million gallons, which would be seen as good for the environment.
October 13th, 2009 at 1:28 pm
What about the busy border crossings? The lineups at some border crossing are perpetual. For example the Peace Arch border crossing south of Vancouver has always had at least a half hour wait in my experience.
Whereas border crossings on the prairies or even at Abbotsford 20 miles away are much less congested.
I’ve often thought that there should be stop lights about 30 or 50 car lengths back from the busy border check points such as the Peach Arch crossing. Let the cars in while the “buffer” fills. Then turn the light red and urge everyone to shut off their vehicle and open the windows and enjoy the weather. Then when the buffer empties turn the light green and let the buffer fill up and turn the light red.
October 13th, 2009 at 2:12 pm
The first study presumes the negative health effect is caused by traffic congestion, but could it also be caused by exposure to repeated rapid acceleration of vehicles exiting the toll booth?
October 14th, 2009 at 3:50 pm
Did they correct for income disparities? Maybe families with EZPass have more money…health and wealth are directly correlated…
October 17th, 2009 at 11:04 pm
@karthik: Here’s a quote: “We find that reductions in traffic congestion generated by E-ZPass reduced the incidence of prematurity and low birth weight among mothers within 2km of a toll plaza by 10.8% and 11.8% respectively.”
It was not whether or not the family had an EZ-Pass in their car(s) but rather whether they lived close a toll plaza. For those who lived within 2km of a toll plaza they compared the kids who were born before EZ-Pass was introduced and those born after.
November 5th, 2009 at 8:43 am
the people who have EZ pass here in Baltimore are the ones with above-average incomes. Someone who has EZ pass probably also has decent heath insurance coverage.