The ad hoc working group on the harmonization of RID/ADR/ADN with the UN Recommendations on the Transport of Dangerous Goods is a working group of the RID/ADR/ADN Joint Meeting.

It meets once every two years to draft proposals on how amendments to the UN Model Regulations adopted by the UN Committee of Experts on the Transport of Dangerous Goods and on the Globally Harmonized System of Classification and Labelling of Chemicals can be implemented in RID, ADR and ADN.