The Cross Matrix activity began with TFSL-02-07 (May 2021) defining the concept to assess regulation effects across different areas. TFVS-04-14 (Sep. 2021) clarified building a sound model. Early work 2021-2022 defined traffic and fleet scenarios through TFVS-05-06, TFVS-06-03, TFVS-07-08, and TFVS-06-05, which selected eight scenarios from residential areas to motorways. Activity decreased by 2023, with TFVS-12-06 calling for resumption. TFVS-17-07 compared model results from EU, Switzerland, Japan, and HMG Akustiklabor. Future steps include addressing L_max, traffic measure effects, opening the approach to L categories, and assessing progress from new RD-ASEP in UN R41 06 series.