treasure valley road dust study: final report - ResearchGate

Approximately 8 hours after the initial sanding and sweeping, the emissions potentials
from all sections of both roads has returned to within 15% of their pretreated levels. DRI’s
traffic counter data from Rose Hill on 03/16/01 indicated that 40% of the measured ADT or
~2000 cars traveling at 35 mph passed over the road in the first 8 hours. Similarly, on Chinden it
is estimated that 2000 to 2500 cars traveling at 45 mph passed over each lane in the first 8 hours.
Figure 4-15 shows a picture of the unswept (S3) portion of Rose Hill/Franklin one day
after sand was applied. The travel lanes are clear of visible sand, however much of the material
has migrated over to the untraveled portions of the road. Sand was not visible on the sections
where the road had been swept using either a vacuum or mechanical sweeper.
Sand on
side of road
Figure 4-15. Picture of Franklin Road facing east taken 1 day after sand application. Sand material has
migrated away from the traffic lanes toward the curb.
The results of the winter sanding and sweeping experiment indicate that the direct
impacts of road sanding on PM 10 emissions are short lived lasting no more than 8 hours or 2500
vehicle passes. PM 10 emissions were observed to increase by 25% to 70% at 2.5 hours after the
initial sanding and sweeping. By 8 hours after treatment, the emissions potential from the roads
were indistinguishable from their pretreatment levels. Sweeping using a vacuum or me chanical
system appears to provide no reduction of PM 10 emissions potential when compared with not
sweeping the road. While the sweepers did an excellent job collecting the visible sand on the
roads, the systems tested were ineffective at removing the source of the PM 10 road dust particles.
4.4.2 Summer Street-Sweeping Experiment
During the summer months, the major activity of the ACHD is chip sealing existing
roadways. This process involves several steps. First the roads are swept using vacuum sweepers
to remove any debris, second gravel chips are spread over the roadway and smoothed with a
roller, finally a fogger is used to adhere the chips to the underlying road. The ACHD’s chip
sealing program provided an opportunity to test the effectiveness of street sweeping as a control
to reduce road dust emissions.
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