The Vienna Convention on Road Signs and Signals entered into force on 6 June 1978. The United Nations records that date under Article 39(1) of the treaty.
The convention was adopted at a United Nations conference in Vienna on 8 November 1968. Its purpose was to harmonise road signs, traffic lights and road markings so that international road travel would be easier to understand and safer.
Entry into force did not happen on the day the convention was opened for signature. Article 39 set a threshold of deposited instruments of ratification or accession, followed by a waiting period before the treaty became operative. The fifteenth instrument triggered the process that led to the 1978 effective date.
A frequent confusion is between the convention’s adoption date, its signature date and its entry-into-force date. The year 1968 belongs to the Vienna conference; 1978 is the date the treaty itself became effective. The convention replaced earlier international arrangements concerning road signs and signals among the participating states.