treasure valley road dust study: final report - ResearchGate

Figure 4-17. Map of street sweeper test area in rural Ada County. The shaded ovals are
the areas where the sweeper tests occurred. ....................................................................4-27
Figure 4-18. Comparison of emissions potential from 5 streets in Ada County before and
after street sweeping.......................................................................................................4-28
Figure 5-1. Example of how centroid connectors emulate residential streets. The thin
black lines represent roads in a residential neighborhood. The thick gray lines (1-4)
are the representation of the residential neighborhoods within the Traffic Demand
Model. The point at the center of the picture where the four gray centroid connectors
meet is an example of a Traffic Analysis Zone (TZA). .....................................................5-3
Figure 5-2. Maps of urban/rural zones for year 2000 and future year emissions potentials
calculations. Urban areas are represented by census tracts shaded in black; tracts in
rural areas are white. A census tract is designated as “urban” if the average
population density within the tract >= 1000 per square mile. ............................................5-8
Figure 5-3. VMT growth rate over time. The black diamonds are data from Traffic
Demand Models for the years 2000, 2010, 2015, and 2020. The dashed line is an
exponential fit to the black diamonds and represents the increase of VMT with
calendar year. The black circle is an estimate of VMT for 1991 based on the fit. ..............5-8
Figure 5-4. Map of distributions of road dust emissions. Emissions per link have been
normalized with the length of the link. The units of the numbers in the legend are
grams per day per km of link. Darker lines correspond to links with higher emissions
on a per kilometer basis..................................................................................................5-14
Figure 5-5. Map of distributions of unpaved road dust emissions. Emissions per link have
been normalized with the length of the link. The units of the numbers in the legend
are grams per day per km of link. Darker lines correspond to links with higher
emissions on a per kilometer basis. The thick black spots in Canyon County
correspond to the rural townships. ..................................................................................5-15
Figure 6-1. Schematic of one-dimensional numerical grid. Concentrations are evaluated
between nodes while the remaining parameters are evaluated at the nodes........................6-2
Figure 6-2. Fraction of 7.21 ?m particles that remain in suspension vs. time from
emission...........................................................................................................................6-5
Figure 6-3. Time series of concentration with height for a. neutral conditions and b. stable
conditions.........................................................................................................................6-6
Figure 6-4. Fraction of PM 10 remaining in suspension vs. time after emission. The size
distribution at the point of emission is given in section 4.1. ..............................................6-6
Figure 7-1. PM 10 source profiles of paved and unpaved road dust samples collected in
the Treasure Valley in Winter and Summer 2001..............................................................7-8
Figure 7-2. PM 10 source profiles of road sanding material, chip material used for chipsealing
road resurfacing, and particles collected on filters using the TRAKER
system. All samples were collected in the Treasure Valley in Winter and Summer
2001.................................................................................................................................7-9
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