India: Nonroad Engines

Regulatory Background
Bharat Stage (CEV/Trem) I - III
CEV and Trem Stage IV - V
Locomotives

Regulatory Background

Bharat (CEV) Stage II - III emission standards for diesel construction equipment vehicles were adopted on 21 September 2006. The standards were structured into two tiers:

BS (CEV) II—These standards were based on the EU Stage I requirements, but also cover smaller engines that were not regulated under the EU Stage I.
BS (CEV) III—These standards were based on US Tier 2/3 requirements.

First standards for agricultural tractors, Bharat (Trem) Stage I, became effective in 1999. From the Bharat (Trem) Stage III A, emission requirements for agricultural tractors became harmonized with those for construction machinery for most engine categories.

In March 2018, India adopted Bharat Stage (CEV/Trem) IV - V [3824] emission standards for compression ignition (CI) and positive ignition (PI) nonroad engines used in construction and agricultural equipment. The BS (CEV/Trem) IV emission standards are aligned with EU Stage IV standards, while the BS (CEV/Trem) V standards are aligned with EU Stage V.

In September 2020, the agricultural machinery (Trem) and construction equipment vehicles (CEV) norms were separated. The new terminology replaced Bharat Stage (CEV/Trem)-IV and Bharat Stage (CEV/Trem)-V with Trem Stage-IV and Trem Stage-V for Agricultural Tractors and other Equipment and CEV Stage-IV and CEV Stage-V for Construction Equipment Vehicles [5155].

Bharat Stage (CEV/Trem) I - III

Construction Machinery

The standards are summarized in the following table. The limit values apply for both type approval (TA) and conformity of production (COP) testing. Testing is performed on an engine dynamometer over the ISO 8178 C1 (8-mode) and D2 (5-mode) test cycles.

**Table 1**
Bharat (CEV) Stage II - III emission standards for diesel construction machinery
Engine Power	Date	CO	HC	HC+NOx	NOx	PM
kW	Date	g/kWh
Bharat (CEV) Stage II
P < 8	2008.10	8.0	1.3	-	9.2	1.00
8 ≤ P < 19	2008.10	6.6	1.3	-	9.2	0.85
19 ≤ P < 37	2007.10	6.5	1.3	-	9.2	0.85
37 ≤ P < 75	2007.10	6.5	1.3	-	9.2	0.85
75 ≤ P < 130	2007.10	5.0	1.3	-	9.2	0.70
130 ≤ P < 560	2007.10	5.0	1.3	-	9.2	0.54
Bharat (CEV) Stage III
P < 8	2011.04	8.0	-	7.5	-	0.80
8 ≤ P < 19	2011.04	6.6	-	7.5	-	0.80
19 ≤ P < 37	2011.04	5.5	-	7.5	-	0.60
37 ≤ P < 75	2011.04	5.0	-	4.7	-	0.40
75 ≤ P < 130	2011.04	5.0	-	4.0	-	0.30
130 ≤ P < 560	2011.04	3.5	-	4.0	-	0.20

The Bharat Stage III standards must be met over the useful life periods shown in Table 2. Alternatively, manufacturers may use fixed emission deterioration factors of 1.1 for CO, 1.05 for HC, 1.05 for NOx, and 1.1 for PM.

**Table 2**
Bharat (CEV) Stage III Useful Life Periods
Power Rating		Useful Life Period
Power Rating		hours
< 19 kW		3000
19-37 kW	constant speed	3000
19-37 kW	variable speed	5000
> 37 kW		8000

Agricultural Tractors

Emission standards for diesel agricultural tractors are summarized in Table 3. Emissions are tested over the ISO 8178 C1 (8-mode) cycle.

**Table 3**
Bharat (Trem) Stage I - III A emission standards for diesel agricultural tractors
Engine Power	Date	CO	HC	HC+NOx	NOx	PM
kW	Date	g/kWh
Bharat (Trem) Stage I
All	1999.10	14.0	3.5	-	18.0	-
Bharat (Trem) Stage II
All	2003.06	9.0	-	15.0	-	1.00
Bharat (Trem) Stage III
All	2005.10	5.5	-	9.5	-	0.80
Bharat (Trem) Stage III A
P < 8	2010.04	5.5	-	8.5	-	0.80
8 ≤ P < 19	2010.04	5.5	-	8.5	-	0.80
19 ≤ P < 37	2010.04	5.5	-	7.5	-	0.60
37 ≤ P < 75	2011.04	5.0	-	4.7	-	0.40
75 ≤ P < 130	2011.04	5.0	-	4.0	-	0.30
130 ≤ P < 560	2011.04	3.5	-	4.0	-	0.20

For Bharat (Trem) Stage III A, the useful life periods and deterioration factors are the same as for Bharat (CEV) Stage III, Table 2.

CEV and Trem Stage IV - V

CEV and Trem Stage IV - V emission standards for CI and PI nonroad engines used in construction vehicles and agricultural equipment, respectively, are summarized in Table 4 [3824]. The CEV/Trem Stage-IV emission standards covered nonroad engines with rated power from 37 kW to 560 kW, while the CEV/Trem Stage-V standards cover all power ratings. The regulation includes a six month grace period when registrations of equipment complying with the previous set of emission standards is allowed. In-service conformity checks are required for all CEV/Trem Stage-V engines.

Emissions from compression ignition engines are measured over the NRSC and NRTC test cycles. Positive ignition engines are tested over the NRTC test cycle [AIS-137-Part 7].

The CEV/Trem compliance dates were delayed on several occasions. CEV Stage IV was delayed from 2020.10 to 2021.10. Trem Stage IV was delayed from 2020.10 to 2023.01 [5607][5934]. CEV/Trem Stage V was delayed from 2024.04 to 2025.01/2026.04 [6165].

**Table 4**
CEV and Trem Stage IV - V emission standards
Engine Power	Date	CO	HC	NOx	PM	PN	Test Cycle
kW	Date	g/kWh				1/kWh	Test Cycle
CEV Stage IV and Trem Stage IV
37 ≤ P < 56	CEV: 2021.10 Trem: 2023.01	5.0	4.7*		0.025^a	-	NRSC and NRTC
56 ≤ P < 130		5.0	0.19	0.4	0.025	-
130 ≤ P < 560		3.5	0.19	0.4	0.025	-
CEV Stage V and Trem Stage V
P < 8	CEV: 2025.01 Trem: 2026.04	8.0	7.5*		0.4	-	NRSC or NRTC^b
8 ≤ P < 19		6.6	7.5*		0.4	-	NRSC or NRTC^b
19 ≤ P < 37		5.0	4.7*		0.015	1×10¹²	NRSC and NRTC
37 ≤ P < 56		5.0	4.7*		0.015	1×10¹²
56 ≤ P < 130		5.0	0.19	0.4	0.015	1×10¹²
130 ≤ P < 560		3.5	0.19	0.4	0.015	1×10¹²
P ≥ 560		3.5	0.19	3.5	0.045	-	NRSC
* NOx + HC ^a Applicable for CI engines only ^b NRSC applicable for CI engines, NRTC applicable for PI engines only

2026 Trem Proposal. Under a proposal released in February 2026, the implementation of Trem emission standards for agricultural tractors would be further delayed, with the final implementation date for Trem V standards pushed to 2032.04. The proposed Trem emission standards and implementation dates are summarized in Table 5 (Trem IIIAA/IV/V) and Table 6 (Trem V) [6702].

**Table 5**
Proposed Trem Stage IIIAA/IV/V emission standards
Engine Power	Date	Trem	CO	HC	NOx	PM	PN	Test Cycle
kW	Date	Trem	g/kWh				1/kWh	Test Cycle
P < 8	2026.10	Trem V	8.0	7.5*		0.4	-	NRSC or NRTC^b
8 ≤ P < 19	2026.10	Trem V	6.6	7.5*		0.4	-
19 ≤ P < 37	2028.04	Trem IIIAA	5.0	4.7*		0.35^a	-
37 ≤ P < 56	2023.01	Trem IV	5.0	4.7*		0.025^a	-	NRSC and NRTC
56 ≤ P < 130	2026.10	Trem V	5.0	0.19	0.4	0.015	1×10¹²
130 ≤ P < 560	2026.10	Trem V	3.5	0.19	0.4	0.015	1×10¹²
P ≥ 560	2026.10	Trem V	3.5	0.19	3.5	0.045	-	NRSC
* NOx + HC ^a Applicable for CI engines only ^b NRSC applicable for CI engines, NRTC applicable for PI engines only

**Table 6**
Proposed Trem Stage V emission standards
Engine Power	Date	CO	HC	NOx	PM	PN	Test Cycle
kW	Date	g/kWh				1/kWh	Test Cycle
P < 8	2026.10	8.0	7.5*		0.4	-	NRSC or NRTC^a
8 ≤ P < 19	2026.10	6.6	7.5*		0.4	-	NRSC or NRTC^a
19 ≤ P < 37	2032.04	5.0	4.7*		0.015	1×10¹²	NRSC and NRTC
37 ≤ P < 56	2032.04	5.0	4.7*		0.015	1×10¹²
56 ≤ P < 130	2026.10	5.0	0.19	0.4	0.015	1×10¹²
130 ≤ P < 560	2026.10	3.5	0.19	0.4	0.015	1×10¹²
P ≥ 560	2026.10	3.5	0.19	3.5	0.045	-	NRSC
* NOx + HC ^a NRSC applicable for CI engines, NRTC applicable for PI engines only

Engines equipped with SCR must meet an average ammonia emission limit of 25 ppm for engines ≤ 56 kW and 10 ppm for engines above 56 kW. The limits are defined as a mean value over the NRTC and NRSC cycles.

The standards must be met over the useful life periods shown in Table 7. Alternatively, manufacturers may use fixed emission deterioration factors of 1.3 for CO, 1.3 for HC, 1.15 for NOx, and 1.05 for PM (NRSC and NRTC).

**Table 7**
CEV and Trem Stage IV - V useful life periods
Power Rating (kW)		Useful Life Period
Power Rating (kW)		hours
0 < P < 19		3,000
19 ≤ P < 37	constant speed	3,000
19 ≤ P < 37	variable speed	5,000
P ≥ 37		8,000

Locomotives

In March 2017, India’s Central Pollution Control Board (CPCB) submitted proposed emission standards for diesel locomotives to the Ministry of Environment and Forests (MoEF).

The proposed limits, outlined in a CPCB Interim Report [3643], are based on emission measurements conducted by CPCB on Indian railways.

**Table 8**
Proposed locomotive emission standards, g/bhp-hr
Locomotive Type	CO	HC	NOx	PM
Alco type	3.0	1.00	17.0	0.45
EMD (HHP locomotives)	1.4	1.00	9.0	0.35

There are two sets of limits: for ALCO type locomotives and for high horsepower EMD locomotives. The standards would be applicable through the useful life of the locomotive. The report proposes to define a compliance protocol—including certification, production line testing, and in-use testing—based on the practice followed by US railroads.