Appendix 3.3c Calculation of Emission Factors (Portal)

A sample calculation of the composite emission factor for NO₂ and RSP at the portals is presented below.

Sample:

Segment: 01FM01 02FM01 FM 01FM02 01FN01

|----------------|----------------|------------------------------|----------------|----------------|

50m 50m 190m (enclosure) 50m 50m

The traffic composition is:

Segment	Total (veh/hr)	Bus	HGV	LGV	PC	Taxi
01FM01	4800	192	864	432	2448	864
02FM01	4800	192	864	432	2448	864
FM	4800	192	864	432	2448	864
01FM02	4800	192	864	432	2448	864
01FN01	2800	112	476	252	1456	504

EURO3 emission factors (gm/km-veh) in Year 2011:

Bus	HGV	LGV	PrivateCar	Taxi
6.8	3.84	1.23	0.71	0.73
0.69	0.53	0.11	0.03	0.01

Emission factors E.F. = S Ei * Ni / S Ni

where Ei is the fleet average emission factor of NOx or RSP in the year 2011 and Ni is the number of particular type of vehicles

For Segments (01FM01, 02FM01, FM, 01FM02),

\ E.F. for NOx = (6.8*192+3.84*864+1.23*432+0.71*2448+0.73*864)

4800

= 1.567 gm/km-veh

E.F. for RSP = (0.69*192+0.53*864+0.11*432+0.03*2448+0.01*864)

4800

= 0.15 gm/km-veh

Similarly for Segment (01FN01),

E.F. for NOx = (6.8*112+3.84*476+1.23*252+0.71*1456+0.73*504)

2800

= 1.536 gm/km-veh

E.F. for RSP = (0.69*112+0.53*476+0.11*252+0.03*1456+0.01*504)

2800

= 0.145 gm/km-veh

Mass of pollutant inside enclosure = E.F. of the road * traffic flow * length of the enclosure

\ Mass of NOx inside enclosure = 1.567 * (4800/3600) * (190/1000) = 0.397 gm/s

Mass of RSP inside enclosure = 0.15* (4800/3600) * (190/1000) = 0.038 gm/s

Mass of pollutant in each 50m segment = E.F. of the road * traffic flow * 0.05

\ For Segments (01FM01, 02FM02, 01FM02),

\ Mass of NOx = 1.567 * (4800/3600) * 0.05 = 0.1045 gm/s

Mass of RSP = 0.15 * (4800/3600) * 0.05 = 0.01 gm/s

Similarly, for Segment (01FN01),

\ Mass of NOx = 1.536 * (2800/3600) * 0.05 = 0.0597 gm/s

Mass of RSP = 0.145 * (2800/3600) * 0.05 = 0.00564 gm/s

According to PIARC 91, pollutant is assumed to emit completely out of the enclosure and each ‘portal’ emits 1/2 of the total mass. For each ‘portal’, 2/3 and 1/3 of the emitted mass are assumed to accumulate in the first and second 50 metres, respectively.

\ In Segments (01FM01 and 01FN01),

Mass of NOx from the enclosure = 1/3 * 1/2 * 0.397 = 0.06616 gm/s

Mass of RSP from the enclosoure= 1/3 * 1/2 * 0.038 = 0.00633 gm/s

\ In Segments (02FM01 and 01FM02),

Mass of NOx from the enclosure = 2/3 * 1/2 * 0.397 = 0.13232 gm/s

Mass of RSP from the enclosoure= 2/3 * 1/2 * 0.038 = 0.01267 gm/s

Total Emission Factors in each segment = total mass / traffic flow / 0.05

\ In Segment (01FM01),

Emission Factor of NOx = (0.1045+0.06616) / (4800/3600) / 0.05 = 2.560 gm/veh-km

= 4.12 g/mile-veh

Emission Factor of RSP = (0.01+0.00633) / (4800/3600) / 0.05 = 0.245 gm/veh-km

= 0.39 g/mile-veh

\ In Segments (02FM01 and 01FM02),

Emission Factor of NOx = (0.1045+0.13232) / (4800/3600) / 0.05 = 3.552 gm/veh-km

= 5.72 g/mile-veh

Emission Factor of RSP = (0.01+0.01267) / (4800/3600) / 0.05 = 0.340 gm/veh-km

= 0.55 g/mile-veh

\ In Segment (01FN01),

Emission Factor of NOx = (0.0597+0.06616) / (2800/3600) / 0.05 = 3.236 gm/veh-km

= 5.21 g/mile-veh

Emission Factor of RSP = (0.00564+0.00633) / (2800/3600) / 0.05 = 0.308 gm/veh-km

= 0.50 g/mile-veh