2.3 VEHICULAR SUSPENSION OF PARTICLES


    Formulations used to compute pollutant emissions per unit area resulting from the mechanical disturbances by vehicle traffic are also based on Cowherd et al. (1985). The pollutant emission caused by traffic moving over unpaved surfaces is computed using

(7)



where E10 = emission factor for an unpaved surface expressed as mass suspended per vehicle-kilometer of travel [g/(vehicle-km)]

    Site-specific information from local sources is normally obtained for each of the parameters. When site-specific data are not available, the default values given by Cowherd et al. (1985), which are listed in Table 2.1, may be used.

    Values for p are obtained from a local source of meteorological data.

TABLE 2.1. Default Values for Independent Variables of Equation 7(a,b)
Site  
s(%)
 
S(km/hr)
 
W(Mg)
 
w
Rural/Residential   15 (5-68)   48 (40-64)  
2
 
4
Industrial   8 (2-29)   24 (8-32)  
3
15
26
 
4
6
10
(a) Based on Cowherd et al. (1985).
(b) Numbers in parentheses are ranges of measured values.