8. On behalf of a group of experts, the expert from OICA proposed a number of amendments updating and revising the 03 series of amendments to Regulation No. 51 (ECE/TRANS/WP.29/GRB/2017/6). These proposals received comments from the experts of China, Russian Federation and Switzerland (GRB-66-11, GRB-66-13 and GRB-66-19). The expert from OICA also proposed some further modifications (GRB-66-20).

10. Given a large number of amendment proposals to Regulation No. 51, including the ones transmitted by the Informal Working Group (IWG) on Additional Sound Emission Provisions (ASEP) (see para. 12 below), GRB consolidated and provisionally adopted these proposals, as contained in Annex II. At the same time, GRB was not in a position to reach consensus on whether or not the adopted proposals would require a new series of amendments and/or transitional provisions. GRB decided to come back to this issue at its next session in January 2018. Meanwhile, the secretariat was requested to submit, in December 2017, the adopted text (Annex II) to WP.29 and AC.1 for consideration and vote at their March 2018 sessions as a draft Supplement 3 to the 03 series of amendments to Regulation No. 51, upon the understanding that any possible modifications, to be decided by GRB in January 2018, could exceptionally be submitted to WP.29 as a corrigendum or addendum to the original WP.29 document.

9. The expert from Italy expressed concerns about the suggested extension of the sound pressure level measurement to line BB’ plus 20 m, with the aim to properly assess the possible “backfire”. According to him, this modification would be a new requirement which should be introduced by means of a new series of amendments with transitional provisions, rather than by a supplement, as proposed in ECE/TRANS/WP.29/GRB/2017/6. He also pointed out that the above modification would need to be accompanied with a similar change in the relevant ISO standard. The experts from Germany, Japan, Sweden and Switzerland supported this amendment proposal in the form of a supplement. The expert of the Russian Federation supported the proposal as a supplement and agreed that Regulation No. 51 and the ISO standard should be aligned. The experts from France and EC were of the view that a new series of amendments would be more appropriate.