5. The experts from EC, ETRTO and OICA reported on their studies on sound level limits (GRBP-73-23, GRBP-73-11 and GRBP-73-25, respectively). To coordinate such initiatives, GRBP decided to establish a taskforce (TF) and sought a volunteer among the experts from Contracting Parties to take the leadership of TF, while OICA agreed to act as secretary. GRBP considered that TF should address the sound level limits of UN Regulation No. 51 and, at a later stage, No. 41. To kick-off the TF activities without delay, the Chair pointed out that he could take the lead of TF on a temporary basis, if needed.

6. On behalf of the Informal Working Group on Additional Sound Emission Provisions (IWG ASEP), the expert from Germany introduced a draft new 04 series of amendments to UN Regulation No. 51 (GRBP-73-05). GRBP noted that a revised proposal would be submitted to the next session.

7. The expert from Norway, in his capacity of Chair of the Informal Working Group on Measurement Uncertainties (IWG MU), reported on the progress of IWG MU (GRBP-73-14-Rev.1) and proposed to update its Terms of Reference (GRBP-73-16). GRBP adopted the revised Terms of Reference, as laid down in Annex II of the session report.

8. The experts from IWG MU also presented a draft reference document with a general approach to estimate measurement uncertainties (GRBP-73-15) and draft amendments to the 03 series of amendments to UN Regulation No. 51 (GRBP-73-17).