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NARSTO Workshop on Innovative Methods for Emission Inventory Development and Evaluation University of Texas, Austin October 14-17, 2003 |
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Estimation of Paved and Unpaved Road Dust Emissions in Mexico
Martinus E. Wolf and Paula G. Fields
ERG, Inc., Sacramento, California 95826
Salvador González-Ayala
International Communities Research Center, El Paso, Texas 79936
The first comprehensive national emissions inventory for the country of Mexico is currently under development (a general overview of the Mexico National Emissions Inventory (NEI) project is discussed in a companion presentation by Fields). Two key area source categories in the Mexico NEI are re-entrained dust from paved and unpaved roads. Parameters needed to calculate re-entrained dust emission factors include silt loading, silt content, surface moisture content, mean fleet vehicle weight, mean fleet vehicle speed, and precipitation. Subsequently, it is necessary to determine the vehicle kilometers traveled (VKT) for paved and unpaved roads in order to apply the appropriate emission factors.
This presentation will present the innovative approach used to estimate the percentage of VKT traveled on paved and unpaved roads. The approach builds upon the work previously done to estimate on-road motor vehicle activity data for the Mexico NEI. This presentation will demonstrate the process used to allocate VKT over paved and unpaved roadways in seven representative urban areas of different sizes, including the identification of unpaved roads, development of a GIS data set for unpaved roads, and the estimation of unpaved road VKT. The satellite images and aerial orthographic photographs used to identify unpaved roads will be discussed, as well as the data analysis and interpretation methodologies used. The unpaved road VKT estimation process using traffic modeling initially conducted for the development of the Mexico NEI motor vehicle activity data will also be presented.