17. Upon continued insistence form the WBU, the stationary sound was approved by the IWG to be fitted optionally at the discretion of the manufacturer. The currently available scientific findings do not permit to definitely decide upon the positive or negative effect of that technology. Germany proposes to task an independent consultant to carry out an appropriate study. Members are invited to come forward with proposals for typical traffic conditions that shall be evaluated in that study.

18. The IWG agrees the need to establish scenario in cooperation with WBU to increase scientific knowledge on stationary sound before [deciding whether or not to make] stationary sound mandatory.

19. The IWG proposes to close discussion on stationary sound and keep statement of this first meeting for the informal document to be presented on 61th and for the working document to be presented GRB 62th if GRB members agree.