UN R78 Supplement 1 (05 series) · UNECE Regulation No. 78 (ECE R78) — Uniform provisions concerning the approval of vehicles of categories L1, L2, L3, L4 and L5 with regard to braking.
UN R78 — Supplement 1 to the 05 series of amendments
Base text → Supplement 1
- What changed
- Paragraph 5.1.17.2. no longer limits the braking signal provisions under regenerative braking to vehicles powered solely by electric powertrain.
- The 0.7 m/s² thresholds for the braking signal under regenerative braking are removed. New paragraph 5.1.17.3. says when the signal is kept or not generated.
- Annex 3, paragraph 1.1.3. adds a new item (b): the ASTM F2493-20 standard reference test tyre for the measurement of the PBC.
- Why
- The proposal aims to keep UN Regulation No. 78 aligned with UN Regulation No. 13-H on deceleration thresholds for stop lamps under regenerative braking.
- In UN Regulation No. 13-H, the requirement to deactivate the stop lamp signal when deceleration falls below 0.7 m/s² under regenerative braking was removed.
- The proposal aims to keep ASTM Method E1337 available to determine the PBC in UN Regulation No. 78.
Q1What changed12 changes
Vehicles covered by the braking signal provisions (para. 5.1.17.2.)
Paragraph 5.1.17.2. now applies to vehicles equipped with electric regenerative braking systems which produce a retarding force upon release of the accelerator control. Before this supplement, the paragraph referred to vehicles powered solely by electric powertrain equipped with these systems. The paragraph no longer refers to the definition in paragraph 2.32.
Deceleration thresholds and flickering of the stop lamps (para. 5.1.17.2.)
For a vehicle deceleration by regenerative braking of 1.3 m/s² or less, the signal may be generated. Above 1.3 m/s², the signal must be generated. Before this supplement, the signal was not allowed at vehicle decelerations of 0.7 m/s² or less. The rule that the signal must be de-activated at the latest when the deceleration has fallen below 0.7 m/s² is removed. A new sentence requires an appropriate measure (for example switch-of-hysteresis, averaging, time delay) against fast signal changes that make the stop lamps flicker.
When the signal is kept and when it is not generated (new para. 5.1.17.3.)
Once generated, the signal must be kept as long as a deceleration demand by the electric regenerative braking persists. The signal may be suppressed at standstill. The signal must not be generated when retardation is solely produced by the natural braking effect of the engine, air-/rolling resistance and/or road slope.
New ASTM F2493-20 reference test tyre in item (b) (Annex 3, para. 1.1.3.)
New item (b) adds the ASTM F2493-20 standard reference test tyre, in accordance with ASTM Method E1337-19, at a speed of 40 mph. The PBC is measured as determined by the Type Approval Authority using item (a), (b) or (c). Under a new footnote to item (b), the obtained PBC must be converted into the equivalent value for the ASTM E1136-19 tyre. The conversion must follow the correlation equation described in ASTM E1337-19.
Updated ASTM references in item (a) (Annex 3, para. 1.1.3.)
Item (a) now refers to the ASTM E1136-19 standard reference test tyre and ASTM Method E1337-19. Before this supplement, item (a) referred to E1136-93 (Re-approved 2003) and E1337-90 (Re-approved 2008). The speed of 40 mph does not change.
Wording and punctuation (para. 2.31. and Annex 3, para. 1.1.3.)
In paragraph 2.31., the definition of “Braking Signal” now ends with a full stop instead of a quotation mark and a full stop. Paragraph 1.1.3. of Annex 3 now says “Type Approval Authority” instead of “approval authority”. The text “Measurement of PBC” of paragraph 1.1.3. now ends with a colon. Item (c), the method in Appendix 1 to Annex 3, now ends with a full stop instead of a colon.
Q2Why it changed
- Proposed by
- Expert from the International Motorcycle Manufacturers Association (IMMA)
- Working party
- GRVA, 11th session (27 September – 1 October 2021)
Reasons
The proposal aims to keep UN Regulation No. 78 aligned with the latest amendment to UN Regulation No. 13-H. This amendment concerns the deceleration thresholds for the activation of the stop lamp(s) under regenerative braking. In December 2020, GRVA adopted changes to the braking signal provisions of UN Regulation No. 13-H. The aim was that the stop lamp illumination reflects the intention to decelerate, independently from the type of propulsion. For that purpose, the requirement to deactivate the stop lamp signal when deceleration falls below 0.7 m/s² under regenerative braking was removed.
Sources (3)
“The objective of this proposal is to keep the alignment of UN Regulation No. 78 with the latest amendment to UN Regulation No. 13-H regarding the deceleration thresholds for the activation of the stop lamp(s) under regenerative braking”
“modifying the provisions for the generation of a braking signal to illuminate stop lamps in UN Regulation No. 13-H (ECE/TRANS/WP.29/GRVA/2020/31), to ensure that the stop lamp illumination reflects the intention to decelerate, independently from the type of propulsion.”
“For that purpose, the requirement to deactivate the stop lamp signal when deceleration falls below 0.7 m/s2 under regenerative braking was removed.”
Aligned deceleration thresholds in UN Regulation No. 78 and UN Regulation No. 13-H give consistent stop lamp behaviour across different vehicle categories. This avoids confusing road users driving behind a braking vehicle, regardless of its category.
Sources (2)
“The deceleration thresholds in UN Regulation No. 78 are aligned with those in the current version of UN Regulation No. 13-H”
“which ensures consistent stop lamp behavior across different vehicle categories and therefore avoids confusing road users driving behind a braking vehicle, regardless of its category.”
The proposal aims to keep ASTM Method E1337 available to determine the PBC in UN Regulation No. 78. To do this, the proposal introduces a reference to the new ASTM Standard Reference Test Tyre (SRTT) F2493. ETRTO reported that production of SRTT E1136 would stop during 2020 and that its sales would end by the end of 2021.
Sources (2)
“The objective of this proposal is to ensure the continuity of the ASTM Method E1337 for the determination of the PBC in UN Regulation No. 78, by introducing a reference to the new ASTM Standard Reference Test Tyre (SRTT) F2493”
“the European Tyre And Rim Technical Organization (ETRTO) reported that the production of SRTT E1136 would stop in the course of 2020 and its sales would be discontinued by the end of 2021”
Proposer's reason (informal document GRVA-11-22)
The changes in GRVA-11-22 aim to extend the provisions of paragraph 5.1.17.2. to hybrid vehicles. They also aim to require the activation of the stop lamp under regenerative braking in this powertrain configuration.
Submitted by Expert from IMMA. Working party adoption: ECE/TRANS/WP.29/GRVA/11, para. 99.
Source
“To extend the provisions of paragraph 5.1.17.2. to hybrid vehicles and require the activation of the stop lamp under regenerative braking also in case of this powertrain configuration.”
Proposer's reason (informal document GRVA-11-22)
For clarity and for further alignment with UN Regulation No. 13-H, the table header in paragraph 5.1.17.2. was updated. The new header specifies that the thresholds correspond to the deceleration resulting from the regenerative braking system.
Submitted by Expert from IMMA. Working party adoption: ECE/TRANS/WP.29/GRVA/11, para. 99.
Source
“for the sake of clarity and for further alignment with UN Regulation No. 13-H, the table header in paragraph 5.1.17.2. has been updated to specify that the thresholds correspond to the deceleration resulting from the regenerative braking system”
Document trail
- —ProposalGRVA-10-11Informal proposal by IMMA on the braking signal
- 2021-07RevisedECE/TRANS/WP.29/GRVA/2021/26Official proposal by IMMA, based on GRVA-10-11
- 2021-07ProposalECE/TRANS/WP.29/GRVA/2021/27Proposal by IMMA on the PBC reference test tyre, for the 03, 04 and 05 series
- —Amended in sessionGRVA-11-22IMMA changes to ECE/TRANS/WP.29/GRVA/2021/26
- —Working party adoptsECE/TRANS/WP.29/GRVA/11Session report, para. 99
- 2021-12Sent to WP.29ECE/TRANS/WP.29/2022/13Text that GRVA sent to WP.29 and AC.1
- 2022-03WP.29 adoptsECE/TRANS/WP.29/1164Adopted at the 186th session (session report, para. 132)
- 2022-10-08In forceC.N.340.2022.TREATIES-XI.B.16.78UN depositary notification
Q3Who is affected
Vehicle manufacturer
- For vehicles with electric regenerative braking that produces a retarding force on accelerator release, check the braking signal (para. 5.1.17.2.).
- Make sure that, once generated, the signal is kept while a regenerative braking deceleration demand persists (para. 5.1.17.3.).
- Make sure that retardation solely from the natural braking effects listed in paragraph 5.1.17.3. does not generate the signal.
- Ask the Type Approval Authority if the PBC measurement will use new item (b), the ASTM F2493-20 tyre.
- Update documents that quote paragraph 5.1.17.2. or paragraph 1.1.3. of Annex 3 to the amended text.
Component supplier
- Make sure that the braking signal software uses the 1.3 m/s² threshold for vehicle deceleration by regenerative braking (para. 5.1.17.2.).
- Make sure that an appropriate measure avoids fast signal changes that make the stop lamps flicker (para. 5.1.17.2.).
- Give the vehicle manufacturer updated system documents for paragraphs 5.1.17.2. and 5.1.17.3.
Technical service / Approval authority
- Be ready to assess the braking signal against amended paragraph 5.1.17.2. and new paragraph 5.1.17.3.
- Be ready to measure the PBC with the ASTM F2493-20 tyre in accordance with ASTM Method E1337-19 (item (b)).
- Update your PBC procedures for item (a) of paragraph 1.1.3. to ASTM E1136-19 and ASTM Method E1337-19.
- If item (b) is used, check that the PBC is converted to the E1136-19 equivalent with the E1337-19 equation.
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ⓘ This report gives advice only. It is not legal or type-approval advice.