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).

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. Both comments and pings are currently closed.