treasure valley road dust study: final report - ResearchGate

weeks prior to being swept. While the road sand used by ACHD for traction control purposes is
low in dust content, vehicle tires passing over coarse grains of sand may fracture and pulverize
those grains into PM 10 -sized particles. To exacerbate matters, street sweepers passing over
“aged” road sand may not be as effective in removing the smaller particles resulting from
pulverized sand; preliminary investigation on street sweeper effectiveness indicates that
sweepers may only result in modest removal of PM 10 –sized particles from roads (see section
4.4).
An additional source of geologic material on paved roads can result from the
trackout/carryout of mud from unpaved driveways, roads, and construction sites. Since
precipitation and low temperatures are more prevalent in winter, dirt lots and roads are wet for
longer periods of time than in summer. Vehicles leaving muddy areas may carryout substantial
amounts of mud on the tires and body unto the paved road network.
Third, summer emissions potentials are lower than those for winter and are also relatively
constant over time. This indicates that by the time the summer study had begun, excess
wintertime geologic material -due either to road sanding or vehicle carryout- had been removed
from Ada County roads.
1.6
Emissions Potential [g/vkt/mps]
1.4
1.2
1
0.8
0.6
0.4
0.2
0
2/27/2001
3/1/2001
3/3/2001
3/6/2001
3/10/2001
3/15/2001
3/17/2001
7/12/2001
7/14/2001
7/19/2001
7/20/2001
7/22/2001
Collectors
Interstates
Minor Arterials
Principal Arterials
Residentials
Sample Date
Figure 4-6. Paved road emissions potentials over time by road class. The black double vertical line indicates
the end of the winter sampling and the beginning of summer sampling.
4-18