UN R157 Supplement 6 (00 series) · UNECE Regulation No. 157 (ECE R157) — Uniform provisions concerning the approval of vehicles with regard to Automated Lane Keeping Systems.
UN R157 — Supplement 6 to the 00 series of amendments
Supplement 5 → 6
- What changed
- Paragraphs 5.5.5. and 6.2.2. now use “initiation of the powertrain” instead of “engine start/run cycle”.
- An automatic engine start (or run cycle), for example by a stop/start system, is not an “initiation of the powertrain” anywhere in the Regulation.
- A new footnote refers to the vehicle propulsion system definitions in Mutual Resolution No. 2 (M.R.2).
- Why
- The words “engine” and “run cycle” imply a type of technology and may keep some ambiguity.
- M.R.2 gives generic terms that do not depend on fuel type or technology.
- The term “powertrain” also makes the provisions simpler.
Q1What changed4 changes
Reactivation after a minimum risk manoeuvre (para. 5.5.5.)
After the end of any minimum risk manoeuvre, reactivation of the system is possible only after a new initiation of the powertrain. Before, reactivation was possible only after each new engine start/run cycle. Paragraph 6.2.2. excludes automatic engine starts, for example by a stop/start system, from the term “initiation of the powertrain” in the whole Regulation.
New footnote that refers to the M.R.2 propulsion system definitions
A new footnote refers to the vehicle propulsion system definitions in Mutual Resolution No. 2 (M.R.2), document ECE/TRANS/WP.29/1121.
Off mode at the initiation of the powertrain (para. 6.2.2.)
The default status of the system must be off mode at the initiation of the powertrain. Before, the off mode applied at the initiation of each new engine start/run cycle. An automatic engine start (or run cycle), for example by a stop/start system, is not an “initiation of the powertrain” anywhere in the Regulation. The Regulation no longer has the old sentence that said “this requirement” does not apply to automatic starts. In Annex 5, the test/check entry for paragraph 6.2.2. still uses the old words “Off mode after new engine start/run”.
- The system must be in its default off mode at the initiation of the powertrain (6.2.2.).
- A new initiation of the powertrain meets the condition for reactivation after a minimum risk manoeuvre (5.5.5.).
- The off-mode default of paragraph 6.2.2. does not apply to an automatic engine start, for example by a stop/start system.
- An automatic engine start, for example by a stop/start system, does not meet the 5.5.5. condition for reactivation after a minimum risk manoeuvre.
The earlier text of paragraphs 5.5.5. and 6.2.2. used “each new engine start/run cycle”.
Based on: paragraphs 5.5.5. and 6.2.2. of UN Regulation No. 157 as amended by Supplement 6 (ECE/TRANS/WP.29/2025/63)
Q2Why it changed
- Proposed by
- Expert from the United Kingdom of Great Britain and Northern Ireland
- Working party
- GRVA, 21st session (January 2025)
Reasons
The words “engine” and “run cycle” imply a type of technology. Text that keeps the words “engine” and “run cycle” may stay ambiguous.
Source
“Continuing to refer to ‘engine’ or ‘run cycle’ is still implying a technology type and therefore may retain a level of ambiguity.”
The purpose of Mutual Resolution No. 2 (M.R.2) is to give uniform definitions for vehicle propulsion systems. The generic terms of M.R.2 do not depend on fuel type or technology. M.R.2 therefore gives a basis for provisions that can be technology neutral.
Sources (2)
“was specifically created to establish uniform definitions for vehicle propulsion systems and created generic terms for components and aspects of propulsion systems that are independent of fuel type or technology used”
“It therefore gives the basis for establishing provisions that can be technology neutral.”
The M.R.2 definition of “powertrain” gives a generic term. The term “powertrain” covers the aspect of the vehicle that the text must refer to for the default state of systems after initialisation.
Source
“Using the definition of ‘powertrain’ from M.R.2 provides a generic term that sufficiently covers the aspect of a vehicle which needs to be referred to when considering the default state of systems following initialisation.”
The term “powertrain” also makes the provisions simpler.
Source
“Also using the term ‘powertrain’ simplifies the respective provisions.”
Document trail
- 2024-07ProposalECE/TRANS/WP.29/GRVA/2024/40Earlier proposal by the expert from the United Kingdom
- —RevisedGRVA-20-42Changes from the discussions at the 20th GRVA session
- 2024-11RevisedECE/TRANS/WP.29/GRVA/2025/3Revised proposal for the 21st GRVA session
- —Working party adoptsECE/TRANS/WP.29/GRVA/21Adoption by GRVA at its 21st session (para. 27)
- 2025-04Sent to WP.29ECE/TRANS/WP.29/2025/63Text submitted to WP.29 and AC.1
- 2025-06WP.29 adoptsECE/TRANS/WP.29/1186Adopted at the 196th session (session report, para. 111)
- 2026-01-11In forceC.N.45.2026.TREATIES-XI.B.16.157UN depositary notification
Q3Who is affected
Vehicle manufacturer
- Make sure that the default status of the system is off mode at the initiation of the powertrain (6.2.2.).
- Make sure that reactivation after a minimum risk manoeuvre is possible only after a new initiation of the powertrain (5.5.5.).
- Test that an automatic engine start by a stop/start system does not count as an initiation of the powertrain.
- Update your documents that quote paragraphs 5.5.5. and 6.2.2.
Component supplier
- Make sure that your software logic for paragraphs 5.5.5. and 6.2.2. uses the new term “initiation of the powertrain”.
- Make sure that your software does not treat an automatic stop/start engine start as an initiation of the powertrain.
- Give the vehicle manufacturer updated system documents for paragraphs 5.5.5. and 6.2.2.
Technical service / Approval authority
- When you assess paragraph 5.5.5., do not accept an automatic stop/start engine start as an initiation of the powertrain.
- Compare the Annex 5 test/check entry “Off mode after new engine start/run” with the new paragraph 6.2.2.
- For the term “powertrain”, use the definitions in M.R.2 (document ECE/TRANS/WP.29/1121).
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ⓘ This report gives advice only. It is not legal or type-approval advice.