The Vienna Convention on Road Traffic is an international treaty designed to facilitate international road traffic and to increase road safety by establishing standard traffic rules among the contracting parties. The convention was agreed upon at the United Nations Economic and Social Council's Conference on Road Traffic (7 October – 8 November 1968) and concluded in Vienna on 8 November 1968. This conference also produced the Convention on Road Signs and Signals. The convention had amendments on 3 September 1993 and 28 March 2006. There is a European Agreement supplementing the Convention on Road Traffic (1968), which was concluded in Geneva on 1 May 1971.
The Vienna Convention on Road Traffic was concluded at Vienna on 8 November 1968. Since its entry into force on 21 May 1977, in signatory countries ("Contracting Parties") it replaces previous road traffic conventions, notably the 1949 Geneva Convention on Road Traffic, in accordance with Article 48 of the convention. As of October 2022, the convention has been ratified by 86 countries, but those who have not ratified the convention may still be parties to the 1949 Geneva Convention on Road Traffic. Ireland, Canada, the United States, Cyprus, Iceland, Malta, China and Malaysia are examples of non-signatory countries. Several other countries, such as Spain and Mexico, have signed the convention but have not ratified it.
One of the main benefits of the convention for motorists is the obligation on signatory countries to recognize the legality of vehicles from other signatory countries. The following requirements must be met when driving outside the country of registration:
Cars must display their registration number at the front and rear, even if legislation in the jurisdiction of registration does not require a front vehicle registration plate on cars. Motorcycles need to display their registration number only at the rear. Registration numbers must be composed either of numerals or of numerals and letters. They must be displayed in capital Latin characters and Arabic numerals. In addition to this, the registration number may optionally be displayed in a different alphabet.
A distinguishing sign of the country of registration must be displayed on the rear of the vehicle. This sign may either be placed separately from the registration plate or may be incorporated into the vehicle registration plate.
The physical requirements for the separate sign are defined in Annex 3 of the Vienna Convention on Road Traffic, which states that the letters shall be in black on a white background having the shape of an ellipse with the major axis horizontal. The distinguishing sign should not be affixed in such a way that it could be confused with the registration number or impair its legibility.
When the distinguishing sign is incorporated into the registration plate, it must also appear on the front registration plate of the vehicle, and may be supplemented with the flag or emblem of the national state, or the emblem of the regional economic integration organization to which the country belongs. The distinguishing sign should be displayed on the far left or far right on the registration plate. When a symbol/flag/emblem is also displayed, the distinguishing sign shall obligatorily be placed on the far left on the plate. The distinguishing sign shall be positioned to be easily identifiable and so that it cannot be confused with the registration number or impair its legibility. The distinguishing sign shall therefore be at least a different color from the registration number, or have a different background color to that reserved for the registration number, or be clearly separated from the registration number, preferably with a line.
The vehicle must meet all technical requirements to be legal for road use in the country of registration. Any conflicting technical requirements (e.g., right-hand-drive or left-hand-drive) in the signatory country where the vehicle is being driven do not apply.
The driver must carry the vehicle's registration certificate, and if the vehicle is not registered in the name of an occupant of the vehicle (e.g., a hire car), proof of the driver's right to be in possession of the vehicle.
The convention also addresses minimum mechanical and safety equipment needed to be on board and defines an identification mark (Annex 4) to identify the origin of the vehicle.
Vienna Convention and autonomous driving
One of the fundamental principles of the convention has been the concept that a driver is always fully in control and responsible for the behavior of a vehicle in traffic. This requirement is challenged by the development of technology for collision avoidance systems and autonomous driving.
Since 2021, an automated driving system definition is proposed — in Article 1 of Convention on Road Traffic — as a vehicle system that uses both hardware and software to exercise dynamic control of a vehicle on a sustained basis where Dynamic control is defined as carrying out all the real-time operational and tactical functions required to move the vehicle. This includes controlling the vehicle's lateral and longitudinal motion, monitoring the road, responding to events in the road traffic, and planning and signalling for manoeuvres.
The requirement that every moving vehicle or combination of vehicles shall have a driver is deemed to be satisfied while the vehicle is using an automated driving system which complies with:
(a) domestic technical regulations, and any applicable international legal instrument, concerning wheeled vehicles, equipment and parts which can be fitted and/or be used on wheeled vehicles, and
(b) domestic legislation governing operation.
The effect of this Article is limited to the territory of the Contracting Party where the relevant domestic technical regulations and legislation governing operation apply.
According to a British explanatory Memorandum on the Proposal of Amendment to Article 1 and new Article 34 bis of the 1968 Convention on Road Traffic,