UN R17 Base text (12 series) · UNECE Regulation No. 17 (ECE R17) — Uniform provisions concerning the approval of vehicles with regard to the seats, their anchorages and any head restraints.
UN R17 — 12 series of amendments
Changes from 11 series of amendments (supplement 1)
- What changed
- New paragraph 5.6.8. applies to vehicles of M1 and N1. In a defined position, a 120 +1/-0 mm cylinder must not pass from front to rear through the head restraint structure. In this position, the head restraint is in its lowest position of use and the seat back in its design torso angle.
- New paragraphs 2.31. and 2.32. define “Seat back structure” and “Head restraint structure”. Both definitions use a hardness of more than 50 Shore A.
- New transitional provisions in paragraph 13.15. use the dates 1 September 2026 and 1 September 2028 for type approvals to the preceding series.
- Why
- At GRSP, several experts noted that the proposed changes would be new requirements and so would need a new series of amendments.
- The proposal from CLEPA aims to improve the whiplash behaviour of occupants of smaller stature, in particular of female drivers.
- The proposal adds a geometry check with a cylinder to improve the rearward retention of the head of smaller occupants.
Q1What changed23 changes
New definitions of seat back structure and head restraint structure (paras. 2.31. and 2.32.)
New paragraph 2.31. defines “Seat back structure” as any part of the seat back with a hardness of more than 50 Shore A. New paragraph 2.32. defines “Head restraint structure”. It is any head restraint part that has a hardness of more than 50 Shore A and is situated vertically above the seat back structure.
New head restraint structure requirement with a 120 mm cylinder (para. 5.6.8.)
New paragraph 5.6.8. applies to vehicles of M1 and N1. The seat back is placed in its design torso angle, and the head restraint in its lowest position of use. Then the head restraint structure must not let a 120 +1/-0 mm cylinder pass through it from the front to the rear. The axis of the cylinder is horizontal, in a plane parallel to the longitudinal plane of the vehicle through the R-point of the seat. The lowest edge of the cylinder in its test position must remain above the horizontal tangent to the seat back structure. If the head restraint is integral with the seat back, this edge need not be lower than its front face as defined in paragraph 5.5.1.2.
Paragraphs 5.6.1.1.1. and 5.6.1.1.2. now also refer to paragraph 5.6.8.
Each front outboard head restraint must conform to either paragraph 5.6.1.1.1. or paragraph 5.6.1.1.2., at the choice of the manufacturer. Both paragraphs now also refer to new paragraph 5.6.8. In paragraph 5.6.1.1.1., “5.6.3. through 5.6.7.” is now “5.6.3. through 5.6.8.”.
Transitional provisions: acceptance of type approvals (paras. 13.15. to 13.15.5.)
From the official date of entry into force of the 12 series, no Contracting Party may refuse to grant or accept 12 series type approvals. As from 1 September 2026, Contracting Parties need not accept approvals to a preceding series first issued after 1 September 2026. Until 1 September 2028, they must accept approvals to a preceding series first issued before 1 September 2026, if that series' transitional provisions foresee this. As from 1 September 2028, they need not accept type approvals issued to any preceding series. But for vehicles not affected by the 12 series changes, they must continue to accept such approvals, if that series' transitional provisions foresee this.
Transitional provisions: new approvals and extensions to preceding series (paras. 13.15.6. and 13.15.7.)
Paragraph 13.15.6. says that Contracting Parties may grant type approvals according to any of the preceding series. The earlier text said that they “shall not refuse to grant” UN type approvals according to any preceding series “or extensions thereof”. ECE/TRANS/WP.29/2025/46/Corr.1 deletes paragraph 13.14.5. Paragraph 13.15.7. says that they must continue to grant extensions of existing approvals to any of the preceding series.
Approval mark examples (Annex 2, Models A to D)
In the figures of Models A to D, the approval number “11 2439” is now “12 2439”. The texts under Models B, C and D now refer to the 12 series of amendments instead of the 11 series. In two of the texts, the approval number is now 122439 instead of 112439. One text now refers to seats which “are fitted or capable of being fitted with head restraints”, instead of seats which “are not fitted”.
Q2Why it changed
- Proposed by
- Experts from CLEPA
- Working party
- GRSP, 76th session (December 2024)
Reasons
At GRSP, several experts noted that the changes proposed in ECE/TRANS/WP.29/GRSP/2024/24 would be new requirements. For this reason, they would need a new series of amendments.
Source
“Several experts noted that the proposed changes would amount to new requirements and would therefore need to be reflected in a new series of amendments.”
The proposal from CLEPA aims to improve the whiplash behaviour of occupants of smaller stature, in particular of female drivers.
Source
“The proposal aims to improve the whiplash behaviour of occupants of smaller stature and, in particular, of female drivers.”
In some vehicles, the lowest position of the head restraint may support a smaller occupant's head less well than a medium-sized male's head.
Source
“In some vehicles, the head of a smaller occupant may be less well supported in the lowest position of the head restraint compared to a medium-sized male”
For this reason, the proposal adds a geometry check with a cylinder. The aim is to improve the rearward retention of the head of smaller occupants.
Source
“It is therefore proposed to improve the rearward retention of the head of smaller occupants by adding a geometry check with a cylinder”
Document trail
- 2024-09ProposalECE/TRANS/WP.29/GRSP/2024/24Proposal by the experts from CLEPA for Supplement 1 to the 11 series of amendments
- —RevisedGRSP-76-47-Rev.1Changed proposal by the experts from CLEPA for a 12 series of amendments
- —Working party adoptsECE/TRANS/WP.29/GRSP/76GRSP session report, para. 17 and Annex VI
- 2025-04Sent to WP.29ECE/TRANS/WP.29/2025/46Text that GRSP sent to WP.29 and AC.1
- 2025-05Sent to WP.29ECE/TRANS/WP.29/2025/46/Corr.1Corrigendum to ECE/TRANS/WP.29/2025/46, voted on with it by AC.1
- 2025-06WP.29 adoptsECE/TRANS/WP.29/1186Adopted at the 196th session (session report, para. 111)
- 2026-01-11In forceC.N.21.2026.TREATIES-XI.B.16.17UN depositary notification
Q3Who is affected
Vehicle manufacturer
- For vehicles of M1 and N1, check each head restraint structure against the 120 mm cylinder requirement of paragraph 5.6.8.
- Expect that Contracting Parties need not accept approvals to a preceding series first issued after 1 September 2026 (para. 13.15.2.).
- For vehicles not affected by the 12 series changes, check the preceding series' transitional provisions (para. 13.15.5.).
Component supplier
- Check which parts of your head restraints are “Head restraint structure” under the new definition in paragraph 2.32.
- For head restraints of M1 and N1 vehicles, check the design against the 120 mm cylinder requirement of paragraph 5.6.8.
Technical service / Approval authority
- For M1 and N1 vehicles, check the head restraint structure with the 120 +1/-0 mm cylinder of paragraph 5.6.8.
- Set the seat back to its design torso angle and the head restraint to its lowest use position (para. 5.6.8.).
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ⓘ This report gives advice only. It is not legal or type-approval advice.