treasure valley road dust study: final report - ResearchGate

study in Las Vegas (Kuhns et al., 2001). Figure 3-23 shows the relationship between TRAKER
measurements (T * ) and manually determined silt loadings (sL) in Las Vegas. Note that the
power-law relationship between sL and T * is the same for both Las Vegas and the Treasure
Valley, namely that sL is equal to T * raised to the 0.47 power. However, the relationship is
stronger in the Las Vegas data (R 2 =0.47) than in the Treasure Valley data (R 2 =0.29). There are
two possible explanations for the difference between the Las Vegas and the Treasure Valley
data. First, it is possible that the road dirt in Las Vegas is more uniform in size distribution across
the valley. That is, the relationship between 75 ?m dust particles (this is the nominal upper limit
of the dust particles that are measured using the silt technique) and 10 ?m particles (this is the
upper limit of dust particles measured by the TRAKER) is more consistent in Las Vegas than in
the Treasure Valley. Second, the Las Vegas data span a higher range of numbers (approximately
2.8 orders of magnitude) than the Treasure Valley data (approximately 1.6 orders of magnitude).
Perhaps the higher range of numbers in the Las Vegas study serves to smooth out the noise in the
relationship between TRAKER signal and silt loading, resulting in a better correlation between
the two.
100
Silt Loading (g/m 2 )
10
1
sL = 1.8321(T*) 0.4715
R 2 = 0.2852
sL = 2.0602(T*)
R 2 = 0.1146
0.1
0.01 0.1 1 10 100
Collocated speed-corrected TRAKER signal (mg/m 3 )
Figure 3-22. Relationship between manually collected silt loadings and the speed-corrected TRAKER signal
in the Treasure Valley Idaho. TRAKER measurements were conducted over the same stretch of road where
dirt was subsequently removed by vacuuming for silt analysis. The solid line represents a power law
regression of the data while the dashed line is the linear regression. The low R 2 values for either regression
indicate that the TRAKER signal and silt loadings are only weakly correlated. Silt loadings shown in the
Figure represent samples obtained in both summer and winter 2001. The summer 6 th st. sample has been
omitted.
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