EU: Locomotives: Emissions


The current Stage IV European Union Standards include both locomotives and railcars and set emissions limits (in grams per kWh) for five emissions types (see below). They are aligned with US standards.

Standard type
Conventional pollutant emission limits
Regulating Body
European Union (European Commission, Parliament, Council, and Member States)
Current Standard
Stage IV
Railcars and locomotives with diesel fueled engines of power greater than 130kW


Passed on 16 December 1997, Directive 97/68/EC implements two stages (Stages I & II) of emission limit values for compression ignition engines for common NRMM (non-road mobile machinery). Stage I and II standards cover diesel fuelled engines between 37 and 560 kW, but exclude railcars and locomotives.

Passed on 21 April 2004, Directive 2004/26/EC amends Directive 97/68/EC to include ships, locomotives, and railcars. The directive outlines Stages IIIA, IIIB, and IV of emissions reduction standards. In the Directive, railcars and locomotives are defined as follows:

  • Railcars: Self-propelled, on-track vehicles that are designed to carry freight and/or passengers
  • Locomotives: Self-propelled, on-track vehicles that are designed to propel cars that carry freight and/or passengers, but are not intended to carry goods or passengers themselves.

Stage IIIA is effective (placed on the market) from 1 January 2006 for certain types of engines, Stage IIIB from 1 January 2011, and Stage IV from 1 January 2014. In the directive there is a flexibility scheme that allows manufacturers to place engines on the market that only fulfil the previous stage when a new stage is in force.

The directive 2004/26/EC is aligned with the US proposal Tier IV of further stages of emission limit values.

Technical Standards

Stage III-IV

The different stages in the 2004/26/EC directive are as follows:

  • Stage III A covers engines from 19 to 560 kW including constant speed engines, railcars, locomotives and inland waterway vessels.
  • Stage III B covers engines from 37 to 560 kW including, railcars and locomotives.
  • Stage IV covers engines between 56 and 560 kW.

Stage III A and III B standards have been adopted for engines above 130 kW used for the propulsion of railroad locomotives (categories R, RL, RH) and railcars (RC). There are no upper limits concerning engine power.

Stage III A Standards for Rail Traction Engines
Category Net Power Market Placement Date CO HC HC+NOx NOx PM
kW g/kWh
RC A 130 < P 2006.01 3.5 4.0 0.2
RL A 130 ≤ P ≤ 560 2007.01 3.5 4.0 0.2
RH A 560 < P 2009.01 3.5 0.5* 6.0* 0.2
* HC = 0.4 g/kWh and NOx = 7.4 g/kWh for engines of P > 2000 kW and D > 5 liters/cylinder
Stage III B Standards for Rail Traction Engines
Category Net Power Market Placement Date CO HC HC+NOx NOx PM
kW g/kWh
RC B (railcar) 130 < P 2012.01 3.5 0.19 2.0 0.025
R B (locomotive) 130 < P 2012.01 3.5 4.0 0.025

Testing and Durability

Engines for propulsion of railcars and locomotives are tested using a steady-state procedure (Non-Road Steady Cycle, NRSC). The testing procedure for railcars is identical with the C1 cycle of ISO8178. The procedure for locomotives is identical with the F cycle of ISO8187. Emission durability period (EDP) for Stage III/IV rail traction engines is 10,000 hours.

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