WHDC - World-Wide Harmonized Heavy-Duty Certification ProcedureTest procedure for Diesel engines and gas engines (natural gas or LPG)The objective is to establish a harmonized global technical regulation (GTR) covering the type-approval procedure for heavy-duty engine exhaust emissions.
The regulation is based on new research into the world-wide pattern of real heavy commercial vehicle use. From the collected data, two representative test cycles, a transient test cycle (WHTC) with both cold and hot start requirements and a hot start steady state test cycle (WHSC), have been created covering typical driving conditions in the European Union (EU), the United States of America, Japan and Australia.
The WHTC and WHSC test procedures reflect world-wide on-road heavy-duty engine operation, as closely as possible, and provide a marked improvement in the realism of the test procedure for measuring the emission performance of existing and future heavy duty engines.
In summary, the test procedure was developed so that it would be:
- representative of world-wide on-road vehicle operations,
- able to provide the highest possible level of efficiency in controlling on-road emissions,
- corresponding to state-of-the-art testing, sampling and measurement technology,
- applicable in practice to existing and foreseeable future exhaust emissions abatement technologies, and
- capable of providing a reliable ranking of exhaust emission levels from different engine types.
Currently the GTR is being presented without limit values.
Source: : ECE/TRANS/WP.29/2006/128, 18 July 2006
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