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UN R28 Supplement 7 (00 series) · UNECE Regulation No. 28 (ECE R28) — Uniform provisions concerning the approval of audible warning devices and of motor vehicles with regard to their audible warning signals.

UN R28 — Supplement 7 to the 00 series of amendments

Supplement 6 → 7

Adopted at the WP.29 199th sessionEntry into force not yet known
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What changed
  • The definition of “audible warning device” in paragraph 2.1. adds “or operated by an ADS, as defined in paragraph 11.4.”.
  • Paragraph 14.3.3. now gives the 7.00 ± 0.10 m measuring distance from the front plane of the vehicle, instead of in front of the vehicle.
  • In the case of bi-directional vehicles, the sound pressure must be measured separately for each front plane of the vehicle.
Why
  • TF AVRS prepared the text to make the requirements of UN Regulation No. 28 fit for approval for Automated Driving Systems (ADS).
  • TF AVRS states that it will not add new requirements to the UN Regulations in their current scope.

Q1What changed11 changes

Audible warning device operated by an ADS (paras. 2.1., 11.4. and 11.5.)

The definition of “audible warning device” now ends “intentionally operated by a driver or operated by an ADS, as defined in paragraph 11.4.”. Before this supplement, it ended “intentionally operated by a driver”. New paragraph 11.4. defines an ADS as the vehicle hardware and software that are collectively capable of performing the entire DDT on a sustained basis. New paragraph 11.5. defines the DDT as the real-time operational and tactical functions required to operate the vehicle.

"Audible warning device" means a device consisting of one or several sound emission outlets that are excited simultaneously, emitting an acoustic signal which is intended to give audible warning of the presence of a vehicle in a dangerous road traffic situation , and which is intentionally operated by a driver; or operated by an ADS, as defined in paragraph 11.4.
“Automated Driving System (ADS)” means the vehicle hardware and software that are collectively capable of performing the entire Dynamic Driving Task (DDT) on a sustained basis.
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Measurement distance from the front plane (paras. 11.3. and 14.3.3.)

Under paragraph 14.3.3., the A-weighted sound pressure level must be measured at a distance of 7.00 ± 0.10 m from the front plane of the vehicle. Before this supplement, the distance was 7.00 ± 0.10 m in front of the vehicle. New paragraph 11.3. defines the “front plane” (of the vehicle) as a vertical plane tangent to the leading edge of the vehicle.

The A-weighted sound pressure level emitted by the audible warning device(s), audible warning system(s), multiple audible warning system(s) fitted on the vehicle shall be measured at a distance of 7.00 ± 0.10 m in from the front plane of the vehicle (see figures in Annex 5), which is being placed on an open site, on flat concrete or asphalt surface.
"Front plane” (of the vehicle) means a vertical plane tangent to the leading edge of the vehicle.

Bi-directional vehicles (paras. 11.6., 11.7. and 14.1.3.)

New paragraph 14.1.3. says that, in the case of bi-directional vehicles, the sound pressure must be measured separately for each front plane of the vehicle. New paragraph 11.6. defines a “bi-directional vehicle” as a vehicle that can operate in two opposite forward directions. Paragraph 11.7. defines “forward direction” as a direction intended to be used as main travelling direction of the vehicle.

In the case of bi-directional vehicles, the sound pressure shall be measured separately for each front plane of the vehicle.
“Bi-directional vehicle” means a vehicle that can operate in two opposite forward directions.
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Footnote 1 and a deleted footnote

Footnote 1 now refers to the Consolidated Resolution on the Construction of Vehicles (R.E.3.) in document ECE/TRANS/WP.29/78/Rev.8. Before this supplement, it referred to document ECE/TRANS/WP.29/78/Rev.6, para. 2, and gave a web address. The footnote “See paragraph 6.3.l., footnote 4.” is deleted.

As defined in the Consolidated Resolution on the Construction of Vehicles (R.E.3.), document ECE/TRANS/WP.29/78/Rev.6, para. 2 - www.unece.org/trans/main/wp29/wp29wgs/wp29gen/wp29resolutions.html.) (ECE/TRANS/WP.29/78/Rev.8).
See paragraph 6.3.l., footnote 4.
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Q2Why it changed

Proposed by
Task Force on Automated Vehicles Regulation Screening (TF AVRS)
Working party
GRBP, 82nd session (September 2025)

Reasons

  • TF AVRS prepared the text to make the requirements of UN Regulation No. 28 fit for approval for Automated Driving Systems (ADS).

    Source
    “in order to make the requirements of UN Regulation No. 28 fit for approval for Automated Driving Systems (ADS).”

  • The objective of TF AVRS is to amend the UN Regulations of GRBP, where necessary, so that Automated Driving Systems (ADS) can meet their requirements.

    Source
    “The objective of TF AVRS is to amend the UN Regulations in the purview of GRBP, where necessary, to make it possible for Automated Driving Systems (ADS) to meet the requirements of these Regulations.”

  • TF AVRS states that it will not add new requirements to the UN Regulations in their current scope.

    Source
    “TF AVRS will not add new requirements to the UN Regulations in their current scope.”

Document trail

  1. 2025-06ProposalECE/TRANS/WP.29/GRBP/2025/23Proposal by the Task Force on Automated Vehicles Regulation Screening
  2. —RevisedGRBP-82-13Proposal to replace ECE/TRANS/WP.29/GRBP/2025/23
  3. —Working party adoptsECE/TRANS/WP.29/GRBP/80GRBP session report, paras. 21 and 22
  4. 2026-04Sent to WP.29ECE/TRANS/WP.29/2026/88Text that GRBP sent to WP.29 and AC.1
  5. 2026-06-24WP.29 adoptsECE/TRANS/WP.29/1192Adopted at the 199th session (session report, para. 103)
  6. PendingIn forceDate not yet known

Q3Who is affected

Vehicle manufacturer

  • Check that your sound pressure tests measure 7.00 ± 0.10 m from the front plane of the vehicle (para. 14.3.3.).
  • In the case of bi-directional vehicles, be ready for a separate measurement of each front plane (para. 14.1.3.).

Component supplier

  • No direct action for this role.

Technical service / Approval authority

  • Measure the A-weighted sound pressure level 7.00 ± 0.10 m from the front plane of the vehicle (para. 14.3.3.).
  • In the case of bi-directional vehicles, measure the sound pressure separately for each front plane of the vehicle (para. 14.1.3.).

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ⓘ This report gives advice only. It is not legal or type-approval advice.

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