The use of construction equipment productivity rate model for estimating fuel use and carbon dioxide (CO₂) emissionsCase study: bulldozer, excavator and dump truck

Figures & data

Figure 1 Fuel use and CO₂ emission estimation methodology.

Table 1 Activity input of selected construction equipment.

Equipment	Number of data	Activity input	Unit/type/range
Bulldozer	72	Engine size	80–700 horsepower (hp)
		Distance	50–300 feet (ft)
		Type of soil	Sand–gravel; sandy-clay loam; common earth; clay
Excavator	394	Bucket size	0.5–3.5 cubic yard (cy)
		Trench depth	1–24 ft
		Soil type	Sand–gravel; sandy-clay loam; common earth; clay
		Excavator type	Regular; with truck mounted; with trench box
Dump truck	240	Loading capacity	22–60 cy
		Distance	2000 ft to 4 miles
		Speed	5–25 miles per hour (mph)
		Wait–load–unload time	15–25 minutes (min)

Table 2 Steady-state BSFC for nonroad diesel engines.

Engine horsepower (hp)	Tier level	BSFC (lb/hp-h)
>0–100	0–4	0.408
>100–750	0–4	0.367
>750	0–4	0.367

Table 3 General guide to EPA tier level for off-road diesel engines (EPA 2010).

Engine power	Tier	Years	Engine power	Tier	Years
hp < 11	1	2000–2004	100 ≤ hp < 175	1	1997–2002
	2	2005–2007		2	2003–2006
	4	2008+		3	2007–2011
				4	2012+
11 ≤ hp < 25	1	2000–2004	175 ≤ hp < 300	1	1996–2002
	2	2005–2007		2	2003–2005
	4	2008+		3	2006–2010
				4	2011+
25 ≤ hp < 50	1	1999–2003	300 ≤ hp < 600	1	1996–2000
	2	2004–2007		2	2001–2005
	4	2008+		3	2006–2010
				4	2011+
50 ≤ hp < 75	1	1998–2003	600 ≤ hp < 750	1	1996–2001
	2	2004–2007		2	2002–2005
	3	2008+		3	2006–2010
				4	2011+
75 ≤ hp < 100	1	1998–2003	hp ≥ 750	1	2000–2005
	2	2004–2007		2	2006–2010
	3	2008		4	2011+
	4	2008+

Table 4 Validation results of productivity models.

Equipment	n	R^2	MSPR	MSE
Bulldozer	72	0.9534	0.0023	0.0061
Excavator	394	0.9195	214.5	225.52
Dump truck	240	0.9432	49.28	46.79

Table 5 MLR results for productivity models of three equipments.

Variable	Parameter estimates	p Value
Bulldozer
Intercept	1.87659	< 0.0001
Engine size (hp)	0.00350	< 0.0001
Distance (ft)	− 0.00240	< 0.0001
Soil type 1 – sand–gravel	0.23656	< 0.0001
Soil type 2 – sandy clay–loam	0.21667	< 0.0001
Soil type 3 – common earth	0.16644	< 0.0001
Excavator
Intercept	− 3.946	0.3656
Soil type 1 – common earth	8.465	0.0193
Soil type 2 – sandy clay–loam	14.907	< 0.0001
Soil type 3 – sand gravel	16.412	< 0.0001
Depth	− 2.069	< 0.0001
Bucket size	55.131	< 0.0001
Excavator type 1 – regular	3.317	0.1676
Excavator type 2 – with trench box	4.166	0.4743
Dump truck
Intercept	58.799	< 0.0001
Loading capacity	2.079	< 0.0001
Speed	1.625	< 0.0001
Cycle distance	− 12.056	< 0.0001
Cycle time	− 2.789	< 0.0001

Table 6 Productivity-based total fuel use models.

Equipment	Total fuel use model
Bulldozer	fs (soil type factor): sand–gravel = 0.236; sandy-clay loam = 0.217; common earth = 0.166; clay = 0	(10)
Excavator	fs (soil type factor): common earth = 8.465; sandy-clay loam = 14.907; sand–gravel = 16.412; hard clay = 0ft (scraper type factor): excavator = 3.317; truck-mounted = 4.165; trench-box = 0	(11)
Dump truck		(12)

Note: Q, quantity of soil dozed/moved/excavated (cy); hp, engine horsepower; BSFC, brake specific fuel consumption (gal/hp-h); TAF, transient adjustment factor (unitless); D, distance (ft) – miles for truck; d, depth (ft); B, bucket capacity (cy); C, loading capacity (cy); S, speed (mph); t, cycle time (min).

Table 7 Productivity-based total CO₂ emission models.

Equipment	Total CO2 emission model
Bulldozer	fs (soil type factor): sand–gravel = 0.236; sandy-clay loam = 0.217; common earth = 0.166; clay = 0	(13)
Excavator	fs (soil type factor): common earth = 8.465; sandy-clay loam = 14.907; sand–gravel = 16.412; hard clay = 0ft (scraper type factor): excavator = 3.317; truck-mounted = 4.165; trench-box = 0	(14)
Dump truck		(15)

Note: E, total emissions (g); Q, quantity of soil dozed/moved/excavated (cy); hp, engine horsepower; EFss, steady-state emission factor (g/hp-h); BSFC, brake specific fuel consumption (gal/hp-h); TAF, transient adjustment factor (unitless); DF, deterioration factor (unitless); S_PM, adjustment to PM emission factor for fuel sulphur content (g/hp-h); HC, in-use adjusted hydrocarbon emissions (g/hp-h); 453.6, conversion factor from pounds to grams; 0.87, carbon mass fraction of diesel; 44/12, ratio of CO₂ mass to carbon mass; D, distance (ft or miles); d, trench depth (ft); B, bucket capacity (cy); C, loading capacity (cy); S, average hauling speed (mph); t, load–dump time (min).

Table 8 Bulldozer – model year 2003; 300 ft distance; 1000 cy soil.

Horsepower	Type of material	Productivity (cy/h)	Fuel use (gal)	CO2 (tons)
80	Sand and gravel	18.33	215.84	1.77
80	Sandy clay and loam	17.42	227.11	1.86
80	Common earth	14.88	265.84	2.18
80	Clay	7.85	503.95	4.14
150	Sand and gravel	24.37	273.75	2.50
150	Sandy clay and loam	23.24	287.10	2.62
150	Common earth	20.02	333.27	3.04
150	Clay	10.99	607.09	5.54
275	Sand and gravel	39.07	313.14	2.86
275	Sandy clay and loam	37.41	326.96	2.98
275	Common earth	32.69	374.18	3.42
275	Clay	19.03	642.80	5.87
400	Sand and gravel	60.14	295.88	2.70
400	Sandy clay and loam	57.79	307.80	2.81
400	Common earth	51.07	348.37	3.18
400	Clay	31.21	570.06	5.20
525	Sand and gravel	89.45	261.08	2.38
525	Sandy clay and loam	86.22	270.89	2.47
525	Common earth	76.93	303.58	2.77
525	Clay	48.95	477.09	4.35
600	Sand and gravel	111.90	238.59	2.18
600	Sandy clay and loam	108.03	247.13	2.25
600	Common earth	96.88	275.42	2.51
600	Clay	62.98	423.81	3.87
700	Sand and gravel	148.61	209.55	1.91
700	Sandy clay and loam	143.75	216.71	1.98
700	Common earth	129.70	240.06	2.19
700	Clay	86.49	359.94	3.29

Table 9 Bulldozer – 564 hp; model year 2003; 1000 cy soil.

Distance (ft)	Type of material	Productivity (cy/h)	Fuel use (gal)	CO2 (tons)
50	Sand and gravel	305.24	82.29	0.75
50	Sandy clay and loam	296.60	84.54	0.77
50	Common earth	271.37	92.57	0.84
50	Clay	191.69	130.95	1.19
100	Sand and gravel	249.14	100.60	0.92
100	Sandy clay and loam	241.79	103.86	0.95
100	Common earth	220.40	113.89	1.04
100	Clay	153.31	163.57	1.49
150	Sand and gravel	201.60	124.43	1.14
150	Sandy clay and loam	195.40	128.45	1.17
150	Common earth	177.39	141.49	1.29
150	Clay	121.35	206.72	1.89
200	Sand and gravel	161.61	155.29	1.42
200	Sandy clay and loam	156.42	160.31	1.46
200	Common earth	141.38	177.36	1.62
200	Clay	94.95	264.17	2.41
250	Sand and gravel	128.24	195.68	1.79
250	Sandy clay and loam	123.93	202.45	1.85
250	Common earth	111.46	225.03	2.05
250	Clay	73.36	341.94	3.12
300	Sand and gravel	100.62	249.36	2.28
300	Sandy clay and loam	97.07	258.40	2.36
300	Common earth	86.84	289.00	2.64
300	Clay	55.89	448.81	4.10

Table 10 Excavator – 400 hp; model year 2003; trench: 100 ft long – 10 ft wide; 3 cy bucket size.

Type of soil	Depth (ft)	Productivity (cy/h)	Fuel use (gal)	CO2 (tons)
Common earth	2.5	168.05	9.79	0.09
Loam and sandy clay	2.5	174.50	9.43	0.09
Sand and gravel	2.5	176.00	9.43	0.09
Clay	2.5	159.59	10.32	0.09
Common earth	5	162.88	20.28	0.19
Loam and sandy clay	5	169.32	19.39	0.18
Sand and gravel	5	170.83	19.22	0.18
Clay	5	154.42	21.35	0.19
Common earth	8	156.67	33.63	0.31
Loam and sandy clay	8	163.11	32.20	0.29
Sand and gravel	8	164.62	32.03	0.29
Clay	8	148.21	35.58	0.32
Common earth	12	148.40	53.20	0.49
Loam and sandy clay	12	154.84	51.06	0.47
Sand and gravel	12	156.34	50.53	0.46
Clay	12	139.93	56.40	0.51
Common earth	17	138.05	81.13	0.74
Loam and sandy clay	17	144.49	77.40	0.71
Sand and gravel	17	146.00	76.68	0.70
Clay	17	129.58	86.29	0.79
Common earth	22	127.70	113.34	1.03
Loam and sandy clay	22	134.14	108.00	0.99
Sand and gravel	22	135.65	106.75	0.97
Clay	22	119.24	121.52	1.11

Table 11 Excavator – 400 hp; model year 2003; trench: 100 ft long – 10 ft wide – 12 ft deep.

Type of soil	Bucket vol. (cy)	Productivity (cy/h)	Fuel use (gal)	CO2 (tons)
Common earth	0.63	17.46	445.34	4.13
Loam and sandy clay	0.63	23.90	326.66	3.02
Sand and gravel	0.63	25.41	307.63	2.84
Clay	0.63	9.00	852.24	8.01
Common earth	0.75	24.35	324.35	2.96
Loam and sandy clay	0.75	30.79	256.56	2.34
Sand and gravel	0.75	32.30	244.64	2.23
Clay	0.75	15.89	497.11	4.54
Common earth	1.00	38.13	207.1	1.89
Loam and sandy clay	1.00	44.58	177.21	1.62
Sand and gravel	1.00	46.08	171.52	1.57
Clay	1.00	29.67	266.17	2.43
Common earth	1.50	65.70	120.28	1.10
Loam and sandy clay	1.50	72.14	109.42	1.00
Sand and gravel	1.50	73.65	107.29	0.98
Clay	1.50	57.23	138.07	1.26
Common earth	2.50	120.83	65.3	0.60
Loam and sandy clay	2.50	127.27	62.09	0.57
Sand and gravel	2.50	128.78	61.38	0.56
Clay	2.50	112.37	70.28	0.64
Common earth	3.00	148.40	53.2	0.49
Loam and sandy clay	3.00	154.84	51.06	0.47
Sand and gravel	3.00	156.34	50.53	0.46
Clay	3.00	139.93	56.4	0.51
Common earth	3.50	175.96	44.84	0.41
Loam and sandy clay	3.50	182.40	43.23	0.39
Sand and gravel	3.50	183.91	42.88	0.39
Clay	3.50	167.50	47.15	0.43

Table 12 Truck – 535 hp; model year 2003; 30 cy capacity; 1000 cy soil; 10 mph of speed.

Distance (miles)	Load–dump time (min)	Productivity (cy/h)	Fuel use (gal)	CO2 (tons)
0.38	15	91.02	285.97	2.39
0.38	20	77.07	337.75	2.82
0.38	25	63.13	412.17	3.44
0.57	15	88.72	293.26	2.45
0.57	20	74.78	347.90	2.90
0.57	25	60.84	427.79	3.57
0.76	15	86.43	301.06	2.51
0.76	20	72.49	359.09	3.00
0.76	25	58.55	444.44	3.71
1	15	83.54	311.47	2.60
1	20	69.60	373.92	3.12
1	25	55.65	467.60	3.90
2	15	71.48	364.03	3.04
2	20	57.54	452.25	3.77
2	25	43.60	596.92	4.98
4	15	47.37	549.30	4.59
4	20	33.43	778.29	6.50
4	25	19.48	1335.66	11.15

Table 13 Truck – 535 hp; model year 2003; 1 mile hauling distance; 15 min wait–dump time; 1000 cy soil.

Capacity (lcy)	Speed (mph)	Productivity (cy/h)	Fuel use (gal)	CO2 (tons)
22	5	58.78	404.79	3.70
22	10	66.91	355.77	3.25
22	15	75.03	317.21	2.89
22	20	83.16	286.28	2.61
22	25	91.28	260.82	2.38
30	5	75.42	315.55	2.88
30	10	83.54	284.85	2.60
30	15	91.67	259.63	2.37
30	20	99.79	238.45	2.18
30	25	107.91	220.6	2.01
42	5	100.37	237.02	2.16
42	10	108.49	219.41	2.00
42	15	116.62	203.94	1.86
42	20	124.74	190.85	1.74
42	25	132.87	179.19	1.63
60	5	137.80	172.77	1.58
60	10	145.92	163.01	1.49
60	15	154.04	154.44	1.41
60	20	162.17	146.83	1.34
60	25	170.29	139.69	1.28

EPA. 2001. Non-road Diesel Emission Standards. Washington, DC: EPA's Assessment and Standard Division.

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