India: Nonroad Diesel Engines

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 diesel 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 standards for CEV and Trem were separated and the nomenclature changed [5155].

Bharat Stage (CEV/Trem) I - III

Trem and CEV Stage IV - V

Trem and CEV Stage IV - V emission standards for nonroad diesel engines used in agricultural equipment and construction vehicles are summarized in Table 4 [3824]. The BS IV/V nonroad regulations include no BS IV emission standards for diesel engines with rated power below 37 kW (a category that includes some 90% of agricultural tractors in India) or for engines above 560 kW, but the BS 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. From April 2026, an in-service conformity check is required for all BS V approved engines manufactured.

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]. The CEV/Trem compliance dates were delayed on several occasions. CEV Stage IV was delayed from 2020.10 to 2021.04. 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].

Engines equipped with SCR must meet an 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 5. 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).

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.

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.