Comments on Proposed I-66 Expansion, 2017

Comments prepared for VDOT’s I-66 Corridor Improvements Project Management Team, November 2017.

Thank you for the opportunity to comment on the planned expansion of I-66. I remain concerned that the shared-use trail, as planned, may endanger the health of those who use it regularly, due to concentrated air pollution on the roadway side of the noise barrier.

For the past decade, scientists at the U.S. Environmental Protection Agency have published scholarly papers noting the tendency of noise barriers to concentrate pollutants in a plume that moves up and over the barrier. Hagler et al. (2011) specifically warn that these concentrations may pose a threat to anyone walking or cycling along the barrier: “While ground-level concentrations are reduced behind the barrier, relative to an unobstructed flow situation, on-road concentrations appear to increase with a barrier present. For barrier heights ranging 0.5H to 3H [3-18 meters], on-road concentrations increase correspondingly by a factor of 1.1-2.3, relative to a no-barrier situation. This finding has implications for in-traffic exposure by passengers in vehicles and for bicyclists or pedestrians that may be located on the road side of the barrier.”

Graphs showing concentrated air pollution on roadway side of noise barriers

Baldauf, R. Summary of Noise Barrier and Other Roadside Feature Impacts on Near-Road Air Quality. Presented at TRB Annual Meeting, Washington, DC, January 10 – 14, 2016.

Runners and cyclists are in particular danger. While cycling, people breathe nine times or more as much air per minute than while at rest, thus increasing their exposure to air pollutants. These pollutants can worsen asthma, cardiovascular disease, and diabetes, and increase the likelihood of heart attack and stroke. Children, teenagers, and the elderly are at particular risk. (Shiffman 2017)

We can predict, then, that building the shared-use trail between the road and the noise barrier would force runners and cyclists to breathe in large volumes of concentrated pollutants, resulting in some number of emergency-room visits, hospitalizations, and premature deaths. It is possible that these numbers are low, in which case the current design could be regarded a reasonable compromise between public health concerns and property rights. But it is also possible that the numbers are quite high, in which case I would hope that public health concerns would take priority. 

As it stands, we don’t know how many people would sicken or die as a result of VDOT’s proposed design, nor does VDOT have any plans to find out. At the November 13 meeting at Oakton High School, I spoke with James Ponticello, VDOT air quality program manager, who expressed familiarity with some of the research on the effects of noise barriers in concentrating pollutants. Despite this awareness, he explained that VDOT has taken no steps to measure air quality along existing sound barriers, to model air quality along the proposed shared-use trail, or to set a standard for air quality along the trail. Under this approach, it would be entirely possible for the I-66 expansion as whole to meet EPA standards while confining trail users to a dangerous, concentrated plume of polluted air.

I ask, then, that VDOT use the available science to revise its environmental assessment and predict the air quality specifically along the portions of the shared-use trail planned for both sides of the barrier. This would allow VDOT or others to predict the incidence of disease and death that could be expected from routing the trail inside or outside of the barrier, allowing a more informed debate.

Thank you for your consideration.

Zachary Schrag

Arlington, Virginia

Works Cited

Hagler, Gayle S. W., Wei Tang, Matthew J. Freeman, David K. Heist, Steven G. Perry, and Alan F. Vette. “Model Evaluation of Roadside Barrier Impact on Near-Road Air Pollution.” Atmospheric Environment 45, no. 15 (May 2011): 2522–30.

Shiffman, Richard. “On Your Bike, Watch Out for the Air.” Well (New York Times) (blog), July 6, 2017.

Additional Readings

Baldauf, R., E. Thoma, A. Khlystov, V. Isakov, G. Bowker, T. Long, and R. Snow. “Impacts of Noise Barriers on Near-Road Air Quality.” Atmospheric Environment 42, no. 32 (October 2008): 7502–7.

Bowker, George E., Richard Baldauf, Vlad Isakov, Andrey Khlystov, and William Petersen. “The Effects of Roadside Structures on the Transport and Dispersion of Ultrafine Particles from Highways.” Atmospheric Environment 41, no. 37 (December 2007): 8128–39.

Finn, Dennis, Kirk L. Clawson, Roger G. Carter, Jason D. Rich, Richard M. Eckman, Steven G. Perry, Vlad Isakov, and David K. Heist. “Tracer Studies to Characterize the Effects of Roadside Noise Barriers on Near-Road Pollutant Dispersion under Varying Atmospheric Stability Conditions.” Atmospheric Environment 44, no. 2 (January 2010): 204–14.

Hagler, Gayle S. W., Ming-Yeng Lin, Andrey Khlystov, Richard W. Baldauf, Vlad Isakov, James Faircloth, and Laura E. Jackson. “Field Investigation of Roadside Vegetative and Structural Barrier Impact on Near-Road Ultrafine Particle Concentrations under a Variety of Wind Conditions.” Science of the Total Environment 419, no. Supplement C (March 2012): 7–15.

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