Real-world emissions of in-use off-road vehicles in Mexico

Figures & data

Table 1. Summary of sampled vehicle characteristics.

Code	Equipment	Engine manufacturer	Tier	Model year	hp^a	rpm^b	Cyl.^c	Displacement (L)	Hours of operation	Site^d	Raw data (sec)	Valid data (%)
BH-1	Backhoe	Komatsu	2	2007	96	2200	4	4.5	1,397	APP	6,428	85.1
BH-2	Backhoe	Komatsu	2	2007	96	2200	4	4.5	2,306	AEP	4,806	83.2
BD-1	Bulldozer	Komatsu	3	2008	360	1900	6	15.24	7,504	APP	2,901	84.9
BD-2	Bulldozer	Caterpillar	3	2008	312	1850	6	15.2	1,482	AEP	3,507	89.4
WL-1	Wheel loader	Komatsu	3	2010	531	1800	6	23.15	9,851	APP	4,120	79.8
WL-2	Wheel loader	Komatsu	3	2010	531	1800	6	23.15	10,323	AEP	3,543	86.0
CR	Crane	Linkbelt Hitachi	3	2009	182	2000	6	7.5	5,974	BCS	2,206	88.6
EX	Excavator	Volvo	3	2010	198	1700	6	12.1	3,289	AEP	2,713	96.2
TR	Tractor	New Holland	3	2008	110	2200	4	4.5	NA	ASF	3,191	92.5
AC	Air compressor	Cummins	1	1999	216	1800	6	7	NA	AEP	1,973	79.9
EG	Generator	Cummins	3	2010	32	1500	4	3.9	NA	AEP	3,056	96.9

^aRated horsepower.

^bEngine speed at rated horse power.

^cNumber of cylinders.

^dSampling sites: APP, asphalt-processing plant; AEP, asphalt-excavation plant; BCS, building construction site; ASF, agricultural soil field.

Figure 1. Time-based CO₂, CO, NO_X, and BC emissions rates and corresponding engine speed (RPM) for a bulldozer (BH-2) during a pushing and moving material operation task. F: pushing forward; B: moving backward.

Figure 2. Time-based (gray-filled bars, bottom axes) emission rates and fuel-based (dark transparent bars, top axes) emission factors frequency distributions for CO₂, CO, NO_X, and BC of bulldozer 2 during an earth-pushing working task.

Table 2. Summary of emissions factors for the sampled vehicles without emissions control technology.

Code	Operation	CO2 (g/sec)	CO (mg/sec)	NOX (mg/sec)	BC (mg/sec)	CO (g/kg)	NOX (g/kg)	BC (g/kg)
BH-1	Idling	1.48 (1.4, 1.5)	2.6 (2, 3)	46.1 (44, 48)	0.038 (0.03,0.04)	5.7 (5, 7)	98.9 (97, 101)	0.081 (0.07, 0.08)
	Working with big bucket	8.22 (7.2, 8.9)	40.0 (17, 46)	82.7 (73, 92)	11.9 (3, 12)	16.4 (6, 19)	32.2 (28, 36)	4.83 (1.0, 4.4)
	Working with small bucket	7.17 (6.7, 7.7)	8.7 (6, 11)	74.3 (71, 78)	2.2 (2, 3)	3.9 (3, 5)	33.2 (31, 35)	0.99 (0.7, 1.1)
	Moving	3.62 (3.0, 4.2)	3.7 (2, 4)	62.0 (56, 69)	1.7 (0.6, 2.6)	2.9 (2, 3)	58.2 (50, 64)	1.22 (0.5, 1.7)
BH-2	Idling	1.72 (1.7, 1.7)	5.5 (4, 7)	47.8 (47, 49)	0.026 (0.02, 0.03)	10.0 (7, 12)	87.0 (84, 89)	0.047 (0.04, 0.05)
	Working with big bucket	5.09 (3.5, 5.7)	16.7 (6, 13)	85.3 (73, 95)	2.43 (0.3, 3.0)	9.4 (5, 10)	59.0 (46, 72)	1.75 (0.2, 2.1)
	Working with small bucket	5.14 (4.4, 5.8)	8.0 (6, 9)	84.3 (76, 94)	1.91 (0.6, 2.8)	5.1 (4, 6)	52.3 (48, 57)	1.20 (0.4, 1.8)
BD-1	Idling	2.27 (2.2, 2.3)	6.8 (5, 8)	32.5 (32, 33)	2.00 (1.9, 2.1)	9.3 (8, 11)	41.7 (41, 46)	2.79 (2.6, 2.9)
	Working	19.35 (10.9, 27.1)	261.9 (27, 108)	115.4 (77, 145)	19.6 (5, 18)	40.6 (4, 20)	22.4 (13, 27)	2.87 (1.3, 2.4)
	Moving	6.83 (6.5, 7.3)	24.3 (21, 26)	61.6 (60, 64)	1.69 (1.2, 1.9)	12.0 (11, 13)	32.0 (31, 33)	0.67 (0.5, 0.8)
BD-2	Idling	2.57 (2.4, 2.7)	5.3 (5, 6)	134.3 (129, 136)	0.082 (0.07, 0.09)	6.5 (6, 7)	165.9 (159, 178)	0.100 (0.09, 0.11)
	Backing	12.58 (7.9, 13.9)	19.3 (6, 23)	317.5 (265, 334)	5.4 (2, 7)	4.2 (2, 6)	89.6 (65, 112)	1.18 (0.8, 1.4)
	Pushing	21.83 (17.6, 26.0)	38.3 (27, 49)	480.1 (419, 557)	18.5 (12, 23)	5.8 (4, 7)	73.8 (62, 73)	2.76 (1.8, 3.3)
	Working	17.79 (11.2, 23.2)	44.8 (25, 60)	422.5 (295, 513)	13.4 (3, 19)	7.9 (6, 10)	81.8 (64, 94)	2.18 (0.9, 2.7)
WL-1	Idling	25.77 (24.7, 26.8)	57.4 (29, 85)	220.2 (215, 226)	6.5 (6, 7)	7.0 (3, 10)	27.1 (25, 28)	0.80 (0.7, 0.9)
	Working	55.95 (46.9, 65.7)	6,395.2 (1300, 8700)	257.5 (186, 300)	117.2 (8, 107)	285.7 (67, 387)	12.6 (9, 15)	5.32 (0.4, 5.1)
	Moving	53.06 (45.9, 60.9)	173.5 (18, 181)	191.3 (161, 218)	22.8 (11, 29)	10.2 (1, 10)	12.1 (8, 17)	1.33 (0.7, 1.6)
WL-2	Idling	27.89 (25.3, 30.4)	48.3 (25, 65)	230.6 (218, 247)	6.8 (5, 7)	5.2 (3, 7)	26.5 (26, 27)	0.76 (0.7, 0.8)
	Working	51.02 (46.2, 55.6)	1033.6 (220, 1230)	252.3 (206, 269)	92.3 (12, 95)	62.6 (13, 78)	15.5 (12, 17)	5.68 (0.7, 5.9)
	Loading truck	50.98 (48.2, 57.4)	1557.1 (460, 2120)	301.2 (232, 361)	101.9 (24, 118)	108.5 (26, 135)	19.8 (13, 22)	10.50 (1.4, 7.7)
	Moving	45.10 (35.5, 58.1)	428.7 (70, 470)	219.9 (160, 250)	43.0 (12, 44)	29.6 (6, 35)	16.6 (11, 19)	2.97 (0.8, 2.8)
CR	Idling	NA	NA	18.1 (17.9, 18.3)	0.08 (0.07, 0.09)	NA	NA	NA
	Working	NA	NA	51.3 (46.9, 55.9)	7.56 (0.8, 10.0)	NA	NA	NA
EX	Idling	4.97 (4.9, 5.1)	NA	48.9 (48, 50)	0.070 (0.06, 0.08)	NA	31.9 (31, 32)	0.045 (0.04, 0.05)
	Working	16.28 (16.0, 16.6)	NA	163.4 (161, 167)	4.30 (3.8, 4.5)	NA	31.2 (31, 32)	0.84 (0.7, 0.9)
TR	Idling	1.15 (1.0, 1.2)	18.7 (10, 29)	12.7 (12, 13)	0.014 (0.01, 0.02)	48.6 (30, 74)	34.3 (32, 36)	0.038 (0.03, 0.04)
	Working	3.51 (2.9, 4.1)	32.6 (12, 46)	33.2 (28, 37)	0.54 (0.1, 0.4)	34.7 (14, 46)	32.5 (25, 37)	0.56 (0.1, 0.3)
	Moving	2.79 (2.0, 3.5)	29.8 (14, 40)	26.8 (19, 33)	0.45 (0.1, 0.3)	63.4 (33, 80)	31.7 (21, 38)	0.43 (0.08, 0.2)
AC	Working	5.74 (5.6, 5.8)	18.4 (17, 19)	45.2 (43, 46)	1.58 (1.4, 1.7)	10.1 (10, 11)	24.9 (23, 26)	0.87 (0.8, 0.9)
EG	Working	2.04 (2.02, 2.08)	35.0 (34, 36)	35.7 (35, 37)	0.025 (0.02, 0.03)	53.0 (52, 54)	54.1 (54, 55)	0.038 (0.03, 0.04)

Note. Values represent averages, whereas the numbers in parentheses are the 25th and 75th percentiles . Average CO₂ fuel emission factor for all vehicles is 3120 g/kg-fuel with a 3% standard deviation.

Table 3. Summary of emissions factors for sampled vehicles with emissions control technology.

Code (device)	Operation	CO2 (g/sec)	CO (mg/sec)	NOX (mg/sec)	BC (mg/sec)	CO (g/kg)	NOX (g/kg)	BC (g/kg)
BH-1 (p-DPF)	Idling	1.58 (1.5, 1.6)	2.2 (2, 3)	48.3 (47, 50)	0.026 (0.02, 0.03)	4.4 (3, 6)	96.2 (88, 103)	0.052 (0.05, 0.05)
	Working with big bucket	5.50 (4.7, 6.4)	11.7 (4, 14)	64.6 (57, 73)	2.90 (0.6, 2.3)	7.6 (2, 8)	38.5 (32, 43)	1.89 (0.3, 1.4)
	Moving	4.35 (3.9, 4.8)	3.5 (2, 5)	65.7 (60, 74)	0.78 (0.5, 0.9)	2.9 (2, 4)	47.6 (42, 50)	0.503 (0.36, 0.57)
BH-2 (p-DPF)	Idling	0.75 (0.5, 0.9)	4.0 (3, 5)	18.6 (13, 24)	0.008 (0.005, 0.010)	16.1 (15, 17)	72.9 (72, 73)	0.037 (0.02, 0.05)
	Ramping (1060–1300)	1.48 (1.4, 1.6)	5.3 (4, 6)	29.2 (25, 33)	0.029 (0.02, 0.04)	9.6 (9,11)	58.0 (52, 65)	0.056 (0.04, 0.07)
	Ramping (1400–1530)	1.86 (1.8, 2.0)	3.7 (2, 5)	32.3 (30, 36)	0.050 (0.04, 0.06)	6.8 (6, 8)	52.9 (48, 58)	0.080 (0.06, 0.09)
	Ramping (1690–1840)	2.02 (1.8, 2.3)	7.3 (4, 11)	32.5 (25, 43)	0.092 (0.06, 0.11)	12.7 (11, 14)	47.3 (36, 60)	0.132 (0.08, 0.14)
	Ramping (1910–1960)	2.89 (2.8, 3.0)	4.0 (3, 5)	28.0 (26, 30)	0.139 (0.13, 0.15)	5.9 (4, 7)	29.0 (26, 32)	0.142 (0.13, 0.15)
	Ramping (2140–2330)	2.81 (2.3, 3.4)	9.8 (4, 13)	41.4 (33, 51)	0.235 (0.16, 0.29)	12.8 (9, 14)	44.6 (31, 62)	0.236 (0.16, 0.27)
BD-1 (DPF)	Idling	3.25 (3.1, 3.3)	3.0 (2, 4)	20.0 (19, 20)	0.018 (0.02, 0.02)	2.8 (2, 3)	18.8 (18, 19)	0.017 (0.02, 0.02)
	Ramping (1250–1280)	7.57 (7.4, 7.6)	6.2 (4, 7)	67.3 (64, 71)	0.005 (0.005, 0.006)	2.8 (2, 3)	26.6 (25, 28)	0.002 (0.002, 0.002)
	Ramping (1600–1630)	12.75 (12.6, 12.8)	9.2 (7, 10)	103.2 (101, 104)	0.012 (0.011, 0.013)	2.2 (2, 2)	24.6 (24, 24)	0.003 (0.003, 0.003)
	Ramping (1860–1865)	17.34 (16.9, 17.5)	10.5 (8, 12)	128.0 (123, 130)	0.032 (0.03, 0.04)	1.8 (1, 2)	22.1 (21, 22)	0.006 (0.005, 0.006)
BD-2 (DPF)	Idling	2.43 (2.3, 2.4)	3.3 (2, 4)	25.1 (15, 35)	0.001 (0.001, 0.001)	4.3 (2, 5)	33.2 (21, 46)	0.001 (0.001, 0.002)
	Ramping (960–965)	3.74 (3.6, 3.8)	2.2 (1, 3)	46.3 (43, 48)	0.002 (0.002, 0.002)	1.8 (1, 2)	39.0 (36, 40)	0.002 (0.001, 0.002)
	Ramping (1020–1050)	4.11 (3.9, 4.2)	3.6 (3, 4)	37.7 (34, 37)	0.002 (0.002, 0.003)	2.8 (2, 4)	28.8 (27, 28)	0.002 (0.001, 0.002)
	Ramping (1500–1510)	7.15 (7.3, 7.5)	6.7 (5, 8)	44.0 (37, 44)	0.003 (0.003, 0.004)	3.1 (2, 4)	19.8 (15, 21)	0.002 (0.001, 0.002)
	Ramping (1750–1800)	9.60 (9.8, 10.4)	8.9 (5, 10)	55.8 (40, 65)	0.008 (0.007, 0.008)	3.0 (2, 3)	19.3 (13, 23)	0.003 (0.002, 0.003)
	Ramping (2190–2210)	14.48 (14.4, 15.3)	22.1 (5, 17)	93.0 (56, 115)	0.024 (0.02, 0.03)	5.2 (1, 3)	21.5 (12, 23)	0.005 (0.004, 0.006)
WL-1 (DPF)	Idling	5.69 (5.6, 5.8)	6.2 (5, 8)	55.2 (44, 55)	0.004 (0.004, 0.005)	3.5 (3, 4)	30.2 (25, 30)	0.002 (0.002, 0.003)
	Ramping (1190–1220)	10.35 (10.1, 10.7)	12.5 (10, 15)	97.7 (90, 106)	0.010 (0.01, 0.01)	3.9 (3, 5)	29.8 (28, 32)	0.003 (0.002, 0.003)
	Ramping (1505–1510)	15.09 (14.9, 15.3)	15.6 (12, 19)	229.3 (180, 297)	0.012 (0.01, 0.01)	3.2 (3, 4)	47.8 (37, 63)	0.002 (0.002, 0.003)
	Ramping (1790–1815)	21.55 (21.3, 21.8)	21.1 (19, 24)	347.1 (326, 370)	0.039 (0.03, 0.04)	3.1 (3, 3)	50.8 (47, 54)	0.006 (0.005, 0.006)
WL-2 (DPF)	Idling	5.95 (5.6, 6.4)	4.7 (3, 6)	46.5 (44, 48)	0.005 (0.004, 0.006)	2.6 (2, 4)	24.5 (23, 25)	0.003 (0.002, 0.003)
	Ramping (1210–1230)	9.51 (8.6, 10.5)	17.4 (10, 18)	64.0 (57, 71)	0.011 (0.01, 0.01)	5.8 (3, 6)	21.3 (19, 22)	0.004 (0.003, 0.004)
	Ramping (1265–1275)	12.24 (11.5, 13.3)	43.1 (17, 52)	128.1 (124, 138)	0.056 (0.04, 0.05)	10.6 (4, 12)	32.9 (31, 35)	0.015 (0.01, 0.02)
	Ramping (1490–1500)	14.04 (12.9, 15.4)	30.3 (12, 23)	90.9 (85, 99)	0.022 (0.02, 0.03)	6.9 (2, 6)	20.5 (19, 20)	0.005 (0.004, 0.006)
	Ramping (1515–1545)	15.13 (14.8, 16.1)	13.3 (9, 14)	176.0 (173, 195)	0.223 (0.14, 0.28)	2.9 (2, 3)	36.2 (32, 40)	0.044 (0.03, 0.05)
	Ramping (1790–1805)	21.13 (19.7, 22.4)	61.3 (15, 55)	140.0 (123, 153)	0.387 (0.32, 0.46)	9.5 (2, 7)	21.2 (18, 22)	0.057 (0.05, 0.06)
EX (DPF)	Idling	8.13 (8.0, 8.3)	5.6 (4, 8)	78.4 (72, 86)	0.005 (0.004, 0.007)	2.1 (1, 3)	30.3 (28, 33)	0.002 (0.002, 0.003)
	Working	18.24 (17.2, 19.4)	6.7 (3, 13)	147.3 (138, 154)	0.033 (0.02, 0.04)	1.2 (0.4, 2)	25.6 (24, 26)	0.005 (0.003, 0.007)
	Moving	19.83 (18.3, 21.3)	5.5 (4, 7)	145.4 (130, 160)	0.028 (0.02, 0.03)	0.8 (0.5, 1)	23.5 (22, 24)	0.004 (0.003, 0.005)
TR (p-DPF)	Idling	1.02 (0.9, 1.0)	5.3 (1, 10)	11.2 (11, 12)	0.012 (0.01, 0.01)	16.1 (3, 32)	33.6 (33, 35)	0.035 (0.03, 0.04)
	Working	2.69 (2.1, 3.2)	4.1 (1, 4)	24.3 (21, 28)	0.670 (0.12, 0.58)	5.2 (1, 5)	29.2 (26, 32)	0.642 (0.10, 0.43)
	Moving	2.19 (1.7, 2.6)	6.7 (2, 7)	20.7 (17, 24)	0.308 (0.06, 0.23)	17.6 (6, 19)	28.8 (23, 33)	0.379 (0.06, 0.20)
EG (p-DPF)	Working	2.11 (2.0, 2.2)	36.4 (36, 37)	36.4 (36, 37)	0.018 (0.02, 0.02)	53.0 (52, 54)	53.1 (53, 53)	0.026 (0.02, 0.03)

Note. Values represent averages, and the numbers in parentheses are the 25th and 75th percentiles . Average CO₂ fuel emission factor for all vehicles is 3050 g/kg-fuel with a 3% standard deviation.

Table 4. Comparison of average fuel-based emission factors (g/kg fuel) with other studies.

	Tier	This study^d				Frey et al. (2008)				Durbin et al. (2013)
		MY	NOX	CO	BC	MY	NOX	CO	PM^a	MY	NOX	CO	PM
Backhoes	0					1997	35.2	25	0.35
	1					1999	31.4	12	0.35
						1999	52.1	19	0.25
						2000	26	7.3	0.67
						2001	33.7	11	0.35
	2					2004	39.4	21	0.06	2006	29.7	8.7	0.72
		2007	32.2	16.4	4.83	2004	54.6	3.5	0.25	2006	26.7	11	0.68
		2007	59.0	9.4	1.75	2004	53.3	8.6	0.29	2007	27.4	13	0.79
	3									2010	17.6	7.2	5.06
Bulldozers	0					1988	57.2	19	0.41
						1995	64.8	18	NA
	1					1998	67.9	16	0.32
						2002	37.8	17	0.19
	2					2003	52.4	39	0.48	2003	27	4.9	0.96
						2005	29.8	13	0.25
	3	2008	22.4	40.6	2.87
		2008	81.8	7.9	2.18
		2008^c	22.1	1.8	0.01
		2008^c	21.5	5.2	0.01
	4i									2011^b	10.1	2.3	0.002
										2011^b	9.7	-0.5	0.001
										2012^b	7.6	-0.4	0.002
										2012^b	9.5	-0.7	0.006
										2012^b	8.5	-0.7	0.001
Wheel loaders	1					2002	41.9	13	0.29	2004	24.7	11	0.67
						2002	56.8	12	0.19
						2002	46	4.1	0.32
	2					2004	36.2	14	0.29
						2005	33	11	0.19
	3									2007	25	16	0.71
		2010	12.6	286	5.34					2009	29	19	4.73
		2010	15.5	62.6	5.68					2011	31.3	15	1.77
										2011	17.6	8.1	0.99
										2011	16.8	8.6	1.66
Excavators	1					1998	41.9	8.3	0.25
						2001	46	7.3	0.32
	2					2003	23.2	8.6	0.22
	3									2006	15.3	5	1.52
										2007	15.3	5.8	0.63
		2010	31.2	NA	0.84					2008	17.1	18	2.23
										2011	18.8	5.7	0.93

^aParticle matter values were obtained with light-scattering (opacity) measurements and thus are semiquantitative.

^bThese vehicles were equipped with DPFs and SCR.

^cValues obtained for maximum RPM ramping conditions with DPF installed (no SCR).

^dWithout using emissions control devices, except as noted in footnote c.

Table 5. Corresponding adjusted NRSC fuel-based emission factors for the vehicle types in this study.

Vehicle type	CO (g/kg)	NOx (g/kg)	PM (g/kg)
Backhoe 1	33.1	28.0	1.4
Backhoe 2	33.2	28.0	1.4
Bulldozer 1	13.3	15.7	1.2
Bulldozer 2	14.3	15.7	1.3
Wheel loader 1	13.6	18.2	1.0
Wheel loader 2	13.6	18.2	1.0
Excavator	0.3	15.7	0.9
Tractor	13.8	15.7	0.9
Air compressor	5.0	18.2	1.5
Generator	8.6	34.5	1.1

Durbin, T.D., K. Johnson, E. Jung, and R.L. Russel. 2013. Study of in-use emissions from diesel off-road equipment. College of Engineering–Center for Environmental Research and Technology, University of California Riverside, Riverside, CA. Prepared for California Air Resources Board, ARB contract 08-315; 2013.

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