treasure valley road dust study: final report - ResearchGate

Figure 4-13. Johnston HSD mechanical sweeper.
Once the sand had been swept from sections 1 and 2, the TRAKER vehicle resurveyed
the test sections. TRAKER surveys were repeated at several intervals after the sand was applied
to evaluate how emissions from these different treatments evolve over time.
4.4.1.2 Test Results
Data were reduced by averaging the road dust PM 10 emissions potential b for each test
section and pass. Data from multiple passes over a test section were averaged together if the
passes were made within 10 minutes of one another.
Figure 4-14 shows the results of the sanding/sweeper tests. Chinden Street (top panel)
was on the TRAKER loop so data from this location was sampled on five different occasions
prior to the experiment. The figures show that prior to the sanding sweeping test, the emissions
potential for the three test sections from each road were similar. Emissions potential variation
was less than 10% between the three test sections for both Chinden and Rose Hill/Franklin.
Ten minutes after sand application, no significant change was detected in the emiss ions
potential from the road surface with the exception of the vacuum swept portion of Chinden. The
emissions potential from this section dropped from 0.47 to 0.27 (g/vkt)/(m/s). This initial drop in
potential is probably due to moisture on the road; the sand applied had an approximate moisture
content of 8% (see Appendix A); the first section on Chinden received the sand that had been
sitting at the bottom of the truck bed and was probably more wetted than sand that was applied
later in the test (i.e on sections 2 and 3).
At 2.5 hours after sand application, the emissions potential had increased at all test
sections with respect to the baseline value prior to sanding. At the Chinden test area, the vacuum
swept section S1 emissions potential increased by 26%, the mechanically swept section S2
emissions potential increased by 42%, and the unswept section S3 emission potential increased
by 46%. At the Rose Hill/Franklin test area; emissions potentials increased 69% on the vacuum
swept section, 63% on the mechanically swept section, 61% on the unswept section.
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