The 1958 Agreement on the International Carriage of Dangerous Goods by Road (ADR) is an international treaty that outlines regulations for the transportation of hazardous materials by road. The agreement was signed in Geneva, Switzerland, on 30 September 1957, and it entered into force on 29 January 1968. Since then, the agreement has been amended several times, and its contracting parties have increased over the years.

The ADR agreement has become an essential international instrument in regulating the transport of dangerous goods. It contains provisions on the classification of dangerous goods, packaging, labelling, documentation, and transport operations. The contracting parties to the agreement are countries that have ratified or acceded to it. The current total number of contracting parties is 51.

The contracting parties to the ADR agreement include:

1. Albania

2. Armenia

3. Austria

4. Azerbaijan

5. Belarus

6. Belgium

7. Bosnia and Herzegovina

8. Bulgaria

9. Croatia

10. Cyprus

11. Czech Republic

12. Denmark

13. Estonia

14. Finland

15. France

16. Georgia

17. Germany

18. Greece

19. Hungary

20. Iceland

21. Ireland

22. Italy

23. Kazakhstan

24. Kyrgyzstan

25. Latvia

26. Liechtenstein

27. Lithuania

28. Luxembourg

29. Malta

30. Moldova

31. Montenegro

32. Netherlands

33. North Macedonia

34. Norway

35. Poland

36. Portugal

37. Romania

38. Russian Federation

39. Serbia

40. Slovakia

41. Slovenia

42. Spain

43. Sweden

44. Switzerland

45. Tajikistan

46. Turkey

47. Turkmenistan

48. Ukraine

49. United Kingdom

50. Uzbekistan

51. European Union

The European Union is also a contracting party to the ADR agreement, as it has harmonized the transport of dangerous goods within its member states. The contracting parties to the ADR agreement commit to implementing its provisions within their territories and ensuring that dangerous goods are safely transported across borders.

In conclusion, the contracting parties to the 1958 Agreement on the International Carriage of Dangerous Goods by Road (ADR) are countries that have ratified or acceded to it. The agreement has become an essential international instrument in regulating the transport of dangerous goods by road. As of the time of writing, there are 51 contracting parties to the ADR agreement, including the European Union.