This procedure is based on emission factors issued by the Swiss Federal Office for the Environment (BAFU) for pollutants NOx, CO, HC and SO2, for both cars and HGVs. For each pollutant, a regression curve with polynomes to the 5th degree is used.
Emiss:= a + b * v + c * v2 + d * v3 + e * v4 + f * v5
The parameters a,b,c,d,e and f of the polynome were determined separately for different pollutants for cars and HGVs for the reference years 1990, 1992, and 2000 and are contained in the parameter text files EMI1990.DAT, EMI1992.DAT and EMI2000.DAT. For the reference year 1990, for example, the following values are used.
* Input file for flexible emission formulas for Switzerland 1990
* They are polynome to the 5th degree.
*
* a + bx + cx2 + dx3 + ex4 + fx5 (the numbers are exponential)
* (x is the speed of cars or HGVs)
*
* a + bx + cx2 + dx3 + ex4 + fx5
* NOx CAR
0.75860 2.8004e-2 -9.9187e-4 1.4276e-5 -5.6655e-8 0.0
* NOx HGV
24.216 -0.70194 1.5878e-2 -1.5996e-4 7.1751e-7 0.0
* CO CAR
16.425 -0.38357 2.8706e-3 -4.5425e-6 0.0 0.0
* CO HGV
45.380 -3.0729 9.7880e-2 -1.6116e-3 1.3138e-5 -4.1410e-8
* HC CAR
2.2155 -6.6593e-2 8.7930e-4 -5.1330e-6 1.1381e-8 0.0
* HC HGV
46.490 -3.7859 0.13382 2.3153e-3 1.9258e-5 -6.1410e-8
* SO2 CAR
101.80 -3.0309 4.4557e-2 -2.8928e-4 7.7300e-7 0.0
* SO2 HGV
1980.4 -87.564 2.9120 -5.0701e-2 4.3285e-4 -1.3577e-6
Recent measurements have shown that actual emission values are generally overestimated by 1990 calculation factors, because the change in vehicle fleets (more vehicles have now been equipped with catalytic converters) has contributed to decreasing volumes per vehicle. The latest Swiss emission factors take this change into account with modifications for the years 1992 and 2000.
The polynome approximation of emissions relative to speed shows the following developments for CO for the different reference years in Image 218:
