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Publication Number: FHWA-HRT-12-054
Date: December 2012

 

Methodologies to Measure and Quantify Transportation Management Center Benefits: Final Synthesis Report

Appendix B. Pollutant Emissions

This appendix describes the computations for pollutant emissions. The pollutants discussed are provided in table 34 .

Table 34. Pollutant index identification.

Pollutant Pollutant Index Identification
Volatile organic compound (VOC) PO = 1
Sulfur dioxide (SO2) PO = 2
Oxides of nitrogen (NOX) PO = 3
Particles of 2.5 micrometers or less (PM 2.5) PO = 4
Particles of 10 micrometers or less (PM 10) PO = 5

1 = 0.039 mil

The emission data in this appendix were provided by FHWA using the MOVES model.(31)

B.1 Freeways

Emission rates in terms of grams per VMT are typically relatively low at high speeds
(e.g., 75 mi/h). The rates reduce somewhat as speed decreases and then increase significantly as speed continues to decrease. Emissions for each pollutant for 5-min time periods are modeled by figure 71.

POL open parenthesis PO and N5 closed parenthesis equals V open parenthesis DO and N5 closed parenthesis times LE open parenthesis DO closed parenthesis times the fraction ER open parenthesis PO and SD open parenthesis PO and N5 closed parenthesis closed parenthesis divided by 12.

Figure 71. Equation. Emissions.

Where:

POL = Emissions.
PO = Pollutant.
ER = Emission rate.

The emission rate for each pollutant as a function of speed for years 2011 and 2016 is provided in table 35 and table 36.

Table 35. Emission rates for 2011.

Speed
(mi/h)
Emission Rate (g/mi)
NOX SO2 VOC PM 2.5 PM 10
75 1.062 0.00768 0.1021 0.0261 0.0275
70 1.014 0.00731 0.0934 0.0247 0.0260
65 0.959 0.00705 0.0893 0.0235 0.0247
60 0.922 0.00696 0.0899 0.0228 0.0239
55 0.915 0.00698 0.0930 0.0236 0.0248
50 0.917 0.00707 0.0976 0.0256 0.0268
45 0.923 0.00722 0.1043 0.0274 0.0288
40 0.935 0.00742 0.1137 0.0288 0.0302
35 0.955 0.00770 0.1265 0.0306 0.0321
30 1.028 0.00821 0.1434 0.0370 0.0387
25 1.105 0.00913 0.1638 0.0395 0.0413
20 1.187 0.0102 0.1918 0.0454 0.04766
15 1.294 0.0118 0.2306 0.0511 0.0536
10 1.472 0.0148 0.3025 0.0582 0.0609
5 2.131 0.0240 0.5198 0.0905 0.0945
2.5 3.652 0.0427 0.9618 0.1665 0.1734

Table 36. Emission rates for 2016.

Speed
(mi/h)
Emission Rate (g/mi)
NOX SO2 VOC PM 2.5 PM 10
75 0.621 0.00646 0.0596 0.0172 0.0182
70 0.591 0.00615 0.0523 0.0159 0.0169
65 0.557 0.00593 0.0491 0.0151 0.0160
60 0.536 0.00585 0.0488 0.0146 0.0155
55 0.532 0.00587 0.0504 0.0150 0.0159
50 0.532 0.00595 0.0530 0.0161 0.0169
45 0.534 0.00608 0.0569 0.0171 0.0180
40 0.540 0.00625 0.0626 0.0179 0.0188
35 0.549 0.00648 0.0703 0.0190 0.0200
30 0.589 0.00691 0.0804 0.0226 0.0238
25 0.628 0.00768 0.0910 0.0243 0.0255
20 0.677 0.00857 0.1067 0.0280 0.0294
15 0.741 0.00990 0.1271 0.0315 0.0331
10 0.847 0.01243 0.1637 0.0360 0.0378
5 1.237 0.02028 0.2746 0.0553 0.0581
2.5 2.143 0.03617 0.5019 0.1003 0.1050

To obtain the appropriate emissions rate, interpolation for both speed and the evaluation year should be performed.

B.2 Surface Streets

Signal delay includes the deceleration and acceleration periods associated with a stop for a traffic signal. Since the emission rates associated with these moving periods are somewhat higher than for the idling period, the use of the idling emissions rate to represent the emissions during signal delay period provides a low estimate for the emissions generated during these periods. The relationship for 15-min-period emission levels is provided in figure 72.

POLA open parenthesis PO, LI, LG, and N15 closed parenthesis equals 0.25 times PA open parenthesis PO closed parenthesis times V open parenthesis LI, LG, and N15 closed parenthesis times LCD open parenthesis LI, LG, and N15 closed parenthesis.

Figure 72. Equation. Arterial pollutant emission.

Where:

POLA = Arterial pollutant emission (g).
PO = Pollutant identification.
LI = Intersection ID.
LG = Traffic signal lane group.
PA = Idling emissions generation rate (g/h).
V = Volume (v/h).
LCD = Control delay for the lane group for a vehicle.

Table 37 provides the values for the idling emission rates.

Table 37. Idling emission rates.

Pollutant 2011 Emission Rate (g/h) 2016 Emission Rate (g/h)
NOX 5.858 3.500
SO2 0.0708 0.0669
VOC 3.404 1.642
PM 2.5 0.305 0.213
PM 10 0.318 0.222

 

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