Environmental Engineering Reference
In-Depth Information
1.16 Towards an Improved Characterization
of Dispersion near Major Roadways
Thomas Pierce
1
, David Heist
1
, Vlad Isakov
1
, Steven Perry
1
, Kirk Clawson
2
,
and Richard Eckman
2
1
U.S. Environmental Protection Agency/Office of Research and Development
2
National Atmospheric and Oceanic Administration/Air Resources Laboratory
Abstract
Since the 1980s, there have been few improvements to line-source
dispersion parameterizations in operational dispersion models. Under EPA's Near-
Roadway Research Initiative, research to characterize dispersion near major road-
ways has experienced a resurgence. This paper summarizes an integrated study
involving wind tunnel experiments, ambient field measurements, an SF
6
tracer
field study, and numerical model development and application. The focus of the
study has been to assess the impact of common roadway configurations, such as
road cuts and noise barriers. In particular, the impact of noise barriers, which are
common features along major roadways in the United States, is being examined.
Results to date indicate that noise barriers significantly enhance dispersion of
pollutants near major roadways.
1. Introduction
Over 36 million people in the U.S. live within 100 m of a major highway. A
number of studies have identified adverse effects, including respiratory disease,
cancer, and even mortality, for populations living, working, and/or attending schools
near major roadways. EPA's Clean Air Research Program is emphasizing the need
to characterize atmospheric transport and dispersion of emissions within the first
few hundred meters of roadways, locales often characterized by complex flow
patterns induced by noise barriers, road cuts, buildings and vegetation. This paper
summarizes some of the research activities that are examining this phenomenon.
2. Approach and Results
The approach planned for understanding the spatial distribution of traffic-related
pollutants and for improving tools for simulating the effects of roadside structures
includes the following: (1) Examining existing tools - reviewing and evaluating
