GRVA (based on the tradition of using an acronym from the French “groupe des rapporteurs” and in this case responsible for “véhicules automatisés”) was established by WP.29 during its 175th (June 2018) session via a restructuring of the existing Working Parties. As a result, the GRRF (Brakes and Running Gear) was eliminated and certain of its responsibilities (notably tyres and vehicle combination couplings) were transferred to other Working Parties (GRB and GRSG, respectively).
A convenient calendar of GRVA-related meetings (including its subgroups) can be found here.