ADR and RID stand for the European Agreements Concerning the International Carriage of Dangerous Goods by Rail (RID) and by Road (ADR) and the Joint meeting of RID Safety Committee and the Working Party on the Transport of Dangerous Goods (WP.15).

The RID Safety Committee and WP.15 administer the European Agreements governing the Regulations Concerning the International Transport of Dangerous Goods by Rail (RID) and Road (ADR), respectively.  They meet jointly twice a year in a continuing effort to harmonize the provisions of the two agreements.  The objective is to provide the necessary consistency between highway and rail transport and promote international harmonization.  The UN Recommendations on the Transport of Dangerous Goods serve as a basis for the RID/ADR Agreements.  However, the RID and ADR also include requirements specific to the signatory parties.  Because significant voting majorities of the U.N. Committee of Experts on the Transport of Dangerous Goods are signatory to the RID and ADR Conventions, the work of the RID/ADR Joint Meeting has increasingly stimulated proposals for revisions to the UN Recommendations.  PHMSA represents the U.S. at these meetings, where the U.S. has full voting status.  PHMSA participates in the Joint Meeting to advise U.S. shippers on applicable European requirements, and also to ensure U.S. input into the development of those requirements which, once adopted, are likely to be proposed for adoption in the UN Recommendations.