Global Technical Regulation No. 10

Name:Global Technical Regulation No. 10
Description:Off-cycle Emissions (OCE).
Official Title:Off-cycle Emissions (OCE).
Country:ECE - United Nations
Date of Issue:2009-06-24
Amendment Level:Original
Number of Pages:20
Vehicle Types:Bus, Component, Heavy Truck
Subject Categories:Emissions and Fuel Consumption
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Text Extract:

All InterRegs documents are formatted as PDF files and contain the full text, tables, diagrams and illustrations of the original as issued by the national government authority. We do not re-word, summarise, cut or interpret the regulatory documents. They are consolidated, published in English, and updated on a regular basis. The following text extract indicates the scope of the document, but does not represent the actual PDF content.

September 9, 2009
Created on November 18, 2004, Pursuant to Article 6 of the
(ECE/TRANS/132 and Corr.1)

10. Statement of off-cycle emission compliance
10.1 Example statement of Off-Cycle Emission compliance
10.2 Basis for Off-Cycle Emission compliance statement
11. Documentation

6. The basic regulatory approach historically utilized by a number of countries to reduce
exhaust emissions from heavy-duty engines was to use a combination of an emissions
certification test cycle with an emissions limit (or standard) and a prohibition against the
use of defeat strategies.
7. The test cycle for heavy-duty engines, while different among various countries, had a
number of common characteristics. The test cycle was based on an engine test,
performed in a laboratory, under a limited range of ambient conditions, and the test cycle
contained a pre-defined set of speed and load points always run in the same order. The
prohibition against the use of defeat strategies generally required that the engine could
not operate differently in-use in a manner which reduced the effectiveness of the
engine's emission control system.
8. Heavy-duty vehicles are driven over a wide variety of operating conditions (e.g. starts,
stops, accelerations, decelerations, steady cruises) and under varying ambient
conditions (e.g. temperature, humidity and barometric pressure). The WHDC GTR will
result in a laboratory based test cycle which reflects world-wide on-road heavy-duty
engine operation. However, as with any standardized test cycle, the wide variety of real
world driving conditions cannot be fully incorporated within the WHDC.
9. Heavy-duty engines have progressed over the past decade to include very sophisticated
electronic and mechanical systems. These systems are capable of controlling the
performance of heavy-duty engines over a wide variety of driving conditions. A central
aspect of this sophisticated engineering is the capability to continuously monitor a wide
range of operating parameters, including engine rotational speed, vehicle ground speed,
and intake manifold pressure and temperature, and to modify the performance of the
engine and its emission control systems in real-time in response to the monitored data.
10. Defeat strategy provisions have not generally provided a quantified numerical emissions
limit and associated test procedure for conditions outside of the regulatory test cycles.
This has often resulted in the need for case-by-case decision making during the
certification and type-approval process regarding whether a particular element of design
constitutes a defeat strategy. These design-based reviews have become increasingly
difficult as the engines and the emission control technologies have grown more complex.
11. The approach contained in this OCE GTR may reduce the reliance on case-by-case
design reviews by requiring emission compliance during a wide range off-cycle
operation. The provisions of this GTR supplement the prohibition against defeat
strategies and can allow for a more efficient and objective performance-based means for
evaluating off-cycle emissions behaviour.
12. When considered as a whole, the WHDC GTR and this OCE GTR promote global
harmonization of regulations that reduce air pollution from heavy-duty vehicles and

19. The OCE GTR has been developed with the input and expertise from a large number of
stakeholders, including regulatory authorities, type approval authorities, engine and
vehicle manufacturers, and independent technical consultants. The GTR has built upon
the experience of many organizations and individuals with expertise in addressing
off-cycle emissions.
20. The GTR has been designed to improve the control of off-cycle emissions, and the
WNTE requirements specified in the GTR are based, in-part, on the approaches which
exist in some Contracting Parties' existing legislation.
21. The WNTE requirements in this GTR are a function of the laboratory-based test cycle
limits, specifically emission limits associated with the WHDC GTR's transient test cycle
(the WHTC). However, the WHDC GTR does not currently contain any limit values. For
this reason, no formal analysis of the technical and economic feasibility of the WNTE
limits in this OCE GTR has been undertaken. It is recommended that Contracting
Parties to the 1998 Agreement consider the technical and economic feasibility of the
OCE GTR when they adopt this regulation into their national requirements.
22. This GTR is expected to result in a number of benefits, including: improved emissions
control, more efficient certification or type approval methods, and reduced costs for
engine and vehicle manufacturers.
23. The addition of harmonized defeat strategy provisions and OCE requirements to the
certification testing regime (e.g. the WHDC test cycles) will more adequately ensure that
an appropriate control of emissions is achieved in-use, under a wide range of operating
conditions. As a result, it can be expected that the adoption of this GTR by the
Contracting Parties to the 1998 Agreement will result in an improved level of emissions
24. The GTR may reduce the need for time consuming case-by-case design reviews and
provide a more efficient and objective performance-based means for evaluating off-cycle
25. Finally, heavy-duty engines and vehicles are often produced for the world market. It is
economically more efficient for manufacturers to design and produce models which meet
emissions objectives specified in a common global technical regulation rather than
developing products to meet a wide array of different and potentially conflicting
regulatory requirements in individual countries and regions. This in turn may allow
manufacturers to develop new models more effectively at a lower cost.

3.1. "Auxiliary Emission Strategy" ("AES") means an emission strategy that becomes
active and replaces or modifies a base emission strategy for a specific purpose or
purposes and in response to a specific set of ambient and/or operating conditions and
only remains operational as long as those conditions exist.
3.2. "Base Emission Strategy" ("BES") means an emission strategy that is active
throughout the speed and load operating range of the engine unless an AES is activated.
3.3. "Defeat strategy" means an emission strategy that does not meet the performance
requirements for a base and/or auxiliary emission strategy as specified in this GTR.
3.4. "Element of design" means:
The engine system;
Any control system, including: computer software; electronic control systems; and
computer logic;
Any control system calibration; or
The results of any interaction of systems.
3.5. "Emission strategy" means an element or set of elements of design that is
incorporated into the overall design of an engine system or vehicle and used in
controlling emissions.
3.6. "Emission control system" means the elements of design and emission strategies
developed or calibrated for the purpose of controlling emissions.
3.7. "Engine family" means a manufacturer's grouping of engines as defined in
GTR No. 4.
3.8. "Engine starting" means the process from the initiation of engine cranking until the
engine reaches a speed 150 min below the normal, warmed up idle speed (as
determined in the drive position for vehicles equipped with an automatic transmission).
3.9. "Engine system" means the engine, the emission control system and the
communication interface (hardware and messages) between the engine electronic
control unit(s) and any other powertrain or vehicle control unit.
3.10. "Engine warm-up" means sufficient vehicle operation such that the coolant temperature
reaches a minimum temperature of at least 70 °C.
3.11. "Periodic regeneration" means the regeneration process of an exhaust aftertreatment
system that occurs periodically in typically less than 100 hours of normal engine

5.1.2. Requirements for Auxiliary Emission Strategies (AES)
An AES shall not reduce the effectiveness of the emission control relative to a BES
under conditions that may reasonably be expected to be encountered in normal vehicle
operation and use, unless the AES satisfies one the following specific exceptions:
Its operation is substantially included in the applicable type approval or
certification tests, including the WNTE provisions of Paragraph 7;
It is activated for the purposes of protecting the engine and/or vehicle from
damage or accident;
It is only activated during engine starting or warm up as defined in this GTR;
Its operation is used to trade-off the control of one type of regulated emissions in
order to maintain control of another type of regulated emissions under specific
ambient or operating conditions not substantially included in the type approval or
certification tests. The overall affect of such an AES shall be to compensate for
the effects of extreme ambient conditions in a manner that provides acceptable
control of all regulated emissions.
5.2. World-harmonized Not-To-Exceed Limits for Gaseous and Particulate Exhaust
5.2.1. Exhaust emissions shall not exceed the applicable WNTE emission limits specified in
Paragraph 5.2.2. when the engine is operated in accordance with the conditions and
procedures set out in Paragraphs 6. and 7.
5.2.2. The applicable WNTE emission limits are determined, as follows:
WNTE Emission Limit = WHTC Emission Limit + WNTE Component
"WHTC Emission Limit" is the emission limit (EL) to which the engine is certified pursuant
to the WHDC GTR; and
"WNTE Component" is determined by Equations 1 to 4 in Paragraph 5.2.3.
5.2.3. The applicable WNTE components shall be determined using the following equations,
when the ELs are expressed in g/kWh:
for NOx:
WNTE Component = 0.25 x EL + 0.1
for HC:
WNTE Component = 0.15 x EL + 0.07
for CO:
WNTE Component = 0.20 x EL + 0.2
for PM:
WNTE Component = 0.25 x EL + 0.003
Where the applicable ELs are expressed in units other than units of g/kWh, the additive
constants in the equations shall be converted from g/kWh to the appropriate units.
The WNTE component shall be rounded to the number of places to the right of the
decimal point indicated by the applicable EL in accordance with the rounding method of
ASTM E 29-06.

7.1. World-harmonized Not-To-Exceed Control Area
The WNTE control area consists of the engine speed and load points defined in
Paragraphs 7.1.1. through 7.1.6. Figure 2 is an example illustration of the WNTE control
7.1.1. Engine Speed Range
The WNTE control area shall include all operating speeds between the 30 percentile
cumulative speed distribution over the WHTC test cycle, including idle, (n ) and the
highest speed where 70% of the maximum power occurs (n ). Figure 3 is an example of
the WNTE cumulative speed frequency distribution for a specific engine.
7.1.2. Engine Torque Range
The WNTE control area shall include all engine load points with a torque value greater
than or equal to 30% of the maximum torque value produced by the engine.
7.1.3. Engine Power Range
Notwithstanding the provisions of Paragraphs 7.1.1. and 7.1.2., speed and load points
below 30% of the maximum power value produced by the engine shall be excluded from
the WNTE Control Area for all emissions.
7.1.4. Application of Engine Family Concept
In principal, any engine within a family with a unique torque/power curve will have its
individual WNTE control area. For in-use testing, the individual WNTE control area of
the respective engine shall apply. For type approval (certification) testing under the
engine family concept of the WHDC GTR the manufacturer may optionally apply a single
WNTE control area for the engine family under the following provisions:
A single engine speed range of the WNTE control area may be used; if the
measured engine speeds n and n are within ± 3% of the engine speeds as
declared by the manufacturer. If the tolerance is exceeded for any of the engine
speeds, the measured engine speeds shall be used for determining the WNTE
control area;
A single engine torque/power range of the WNTE control area may be used, if it
covers the full range from the highest to the lowest rating of the family.
Alternatively, grouping of engine ratings into different WNTE control areas is

7.1.5. Compliance Exclusion from Certain WNTE Operating Points
The manufacturer may request that the approval authority excludes operating points
from the WNTE control area defined in Paragraph 7.1.1 through 7.1.4 during the
certification/type approval. The approval authority may grant this exclusion if the
manufacturer can demonstrate that the engine is never capable of operating at such
points when used in any vehicle combination.
7.2. Minimum World-harmonized Not-To-Exceed Event Duration and Data Sampling
7.2.1. To determine compliance with the WNTE emissions limits specified Paragraph 5.2., the
engine shall be operated within the WNTE control area defined in Paragraph 7.1. and its
emissions shall be measured and integrated over a minimum period of 30 seconds. A
WNTE event is defined as a single set of integrated emissions over the period of time.
For example, if the engine operates for 65 consecutive seconds within the WNTE control
area and ambient conditions this would constitute a single WNTE event and the
emissions would be averaged over the full 65 second period. In the case of laboratory
testing, the integrating period of time set out in Paragraph 7.5 shall apply.
7.2.2. For engines equipped with emission controls that include periodic regeneration events, if
a regeneration event occurs during the WNTE test, then the averaging period shall be at
least as long as the time between the events multiplied by the number of full
regeneration events within the sampling period. This requirement only applies for
engines that send an electronic signal indicating the start of the regeneration event.
7.2.3. A WNTE event is a sequence of data collected at the frequency of at least 1 Hz during
engine operation in the WNTE control area for the minimum event duration or longer.
The measured emission data shall be averaged over the duration of each WNTE event.
7.3. World-harmonized Not-To-Exceed In-use Testing
If a Contracting Party selects this GTR as basis for in-use testing, the engine shall be
operated under actual in-use conditions. The test results out of the total data set that
comply with the provisions of Paragraphs 6., 7.1. and 7.2. shall be used for determining
compliance with the WNTE emission limits specified in Paragraph 5.2. It is understood
that emission during some WNTE events may not be expected to comply with the WNTE
emission limits. Therefore, Contracting Parties should define and implement statistical
methods for determining compliance that are consistent with Paragraphs 7.2. and 7.3.

7.5. Laboratory Test Procedure
7.5.1. After warm up, the engine shall be preconditioned at mode 9 of the WHSC for a
minimum period of 10 minutes. The test sequence shall start immediately after
completion of the preconditioning phase.
7.5.2. The engine shall be operated for 2 minutes at each random test point. This time
includes the preceding ramp from the previous steady state point. The transitions
between the test points shall be linear for engine speed and load and shall last
20 ± 1 seconds.
7.5.3. The total test time from start until finish shall be 30 minutes. The test of each set of
5 selected random points in a grid cell shall be 10 minutes, measured from the start of
the entry ramp to the 1st point until the end of the steady state measurement at the
5th point. Figure 5 illustrates the sequence of the test procedure.
7.5.4. The WNTE laboratory test shall meet the validation statistics of Paragraph 7.7.2. of the
7.5.5. The measurement of the emissions shall be carried out in accordance with
Paragraph 7.8. of WHDC GTR.
7.5.6. The calculation of the test results shall be carried out in accordance with Paragraph 8. of
Figure 4
Schematic Example of the Start of the WNTE Test Cycle

7.6. Rounding
Each final test result shall be rounded in one step to the number of places to the right of
the decimal point indicated by the applicable WHDC emission standard plus one
additional significant figure, in accordance with ASTM E 29-06. No rounding of
intermediate values leading to the final brake specific emission result is permitted.
The concept of a deficiency is to allow an engine or vehicle to be certified as compliant
with a regulation even though specific requirements, limited in scope, are not fully met. A
WNTE deficiency provision would allow a manufacturer to apply for relief from the WNTE
emission requirements under limited conditions, such as extreme ambient temperatures
and/or severe operation where vehicles do not accumulate significant mileage.
Contracting Parties may wish to consider providing WNTE deficiency provisions in
regional legislation.
The concept of a WNTE exemption is a set of technical conditions specified by a
Contracting Party under which the WNTE emission limits set out in this GTR would not
apply. A WNTE exemption shall apply to all engine and vehicle manufacturers.
A Contracting Party may decide to provide a WNTE exemption, in particular with the
introduction of more stringent emission limits. For example a WNTE exemption may be
necessary if a Contracting Party determines that certain engine or vehicle operation
within the WNTE control area cannot achieve the WNTE emission limits. In such a case,
the Contracting Party may determine that it is not necessary for engine manufacturers to
request a WNTE deficiency for such operation, and that the granting of a WNTE
exemption is appropriate. The Contracting Party can determine both the scope of the
exemption with respect to the WNTE requirements, as well as the period of time for
which the exemption is applicable.
In the application for certification or type approval the manufacturer shall provide a
statement that the engine family or vehicle complies with the requirements of this OCE
GTR. In addition to this statement, compliance with the WNTE limits shall be verified
through additional tests and certification procedures defined by the Contracting Parties.
10.1. Example Statement of Off-Cycle Emission Compliance
The following is an example compliance statement:
"(Name of manufacturer) attests that the engines within this engine family comply with all
requirements of the OCE GTR. (Name of manufacturer) makes this statement in good
faith, after having performed an appropriate engineering evaluation of the emissions
performance of the engines within the engine family over the applicable range of
operating and ambient conditions."

Off-cycle Emissions (OCE).