45. GRSG resumed discussion on the proposal of CLCCR on assisting driven axles of trailers (ECE/TRANS/WP.29/GRSG/2023/5). The expert from Germany mentioned GRSG-127-01 and explained that the investigation of the Federal Highway Research Institute (BASt) of Germany had been presented at the October 2023 session of GRSG. He added that the current definition of trailers need not be changed if the trailers lacked a driving force. The expert from the Netherlands reminded GRSG that the issue should be dealt with differently in working groups. He announced that a revised proposal was prepared by CLCCR, France and the Netherlands for the upcoming GRSP that addresses UN Regulation No. 100 (Electric power trained vehicles). He clarified that the proposal would also consider the trailer as a generator of electricity in a first stage and possible traction to compensate for internal losses in a second stage. The OICA expert endorsed the statement from the expert from the Netherlands and informed GRSG that a proposal addressing this kind of trailer was under discussion in GRVA. The expert from China informed GRSG that in his country, studies had been developed and research made on this subject. GRSG agreed to resume discussion on this subject at its October 2024 session.

34. The expert from Germany introduced GRSG-126-04, to express support for the proposal from the International Association of the Body and Trailer Building Industry (CLCCR) of assisting driven axles on trailers (ECE/TRANS/WP.29/GRSG/2023/5). He also informed GRSG about the investigation of the Federal Highway Research Institute (BASt) in his country on the influence that driven trailers can have on the driving dynamics of combinations compared to non-driven trailers. He added that BASt had concluded that driven trailers did not negatively impact on vehicle safety in certain conditions. Therefore, he stated that these kinds of axles can distribute and use energy storage more efficiently. The experts from CLEPA and OICA supported the CLCCR proposal and expected coordination between the different working groups to introduce type approvals for this new type of trailer. The expert from France supported the proposal and suggested targeting different combinations of these trailers. GRSG agreed to resume discussion on this agenda item at its April 2024 session based on a revised proposal from CLCCR. At the same time, the Chair was requested to report the highlights of the session to the November 2024 session of WP.29 and to seek guidance on a coordinated activity with other working groups.

39. GRSG agreed to defer discussion on ECE/TRANS/WP.29/GRSG/2023/5, tabled by the expert from the International Association of the Body and Trailer Building Industry (CLCCR) to its October 2023 session.

32. The experts from CLCCR and CLEPA introduced GRSG-124-12 superseding ECE/TRANS/WP.29/GRSG/2022/17, to clarify the definition of a trailer/semi-trailer in case one or more trailer axles may be driven by a propulsion type integrated into the trailer (e.g. electric engine) in combination with the motor vehicle. The expert from the Netherlands expressed a study reservation on the proposal and recommended that parallel amendments be introduced in other UN Regulations such as UN Regulation No. 13 (Heavy vehicle braking). At the same time, he recalled to GRSG that UN Regulation No. 100 does not apply to trailer categories O₃ and O₄. GRSG agreed to resume discussion at its March 2023 session and requested the secretariat to distribute GRSG-124-12 with an official symbol.

56. The expert from CLCCR introduced ECE/TRANS/WP.29/GRSG/2022/17 to amend the consolidated Resolution on the Construction of Vehicles (R.E.3) by clarifying the definition of a trailer/semi-trailer in case one or more trailer axles may be driven by a propulsion type integrated into the trailer (e.g. electric engine) in combination with the motor vehicle. The expert from United Kingdom remarked on an inconsistency in the text of the proposal between the contribution to the propelling forces of the vehicle combination at all speeds and the speed limit of 15 km/h. The expert from the Netherlands added that amending R.E.3. and Special Resolution No. 1 (S.R.1) would be just a first step because a number of UN Regulations also need amendment (e.g. UN Regulations Nos. 13, 55 and 100) to allow for the introduction of such semi-trailers and full-trailers.

57. Finally, GRSG agreed to resume discussion on this subject at its October 2022 session on the basis of a revised proposal superseding ECE/TRANS/WP.29/GRSG/2022/17.