# Vienna Convention on Road Signs and Signals

The Convention on Road Signs and Signals, commonly known as the Vienna Convention on Road Signs and Signals, is a multilateral treaty to standardize the signing system for road traffic (road signs, traffic lights and road markings) in use internationally.

## History

This convention was agreed upon by the United Nations Economic and Social Council at its Conference on Road Traffic in Vienna 7 October to 8 November 1968, was concluded in Vienna on 8 November 1968, and entered into force on 6 June 1978. This conference also produced the Vienna Convention on Road Traffic, which complements this legislation by standardising international traffic laws.
The convention revised and substantially extended the earlier 1949 Geneva Protocol on Road Signs and Signals, itself based in turn on the 1931 Geneva Convention concerning the Unification of Road Signals. Amendments, including new provisions regarding the legibility of signs, priority at roundabouts, and new signs to improve safety in tunnels were adopted in 2003.
Both the Vienna Convention and the Geneva Protocol were formed according to consensus on road traffic signs that evolved primarily in 20th century continental Western Europe. In order to make it as universal as possible, the convention allows some variations, for example danger warning signs can be triangular or square diamond in shape and road markings can be white or yellow. Though most UN members have not ratified the full treaty, the signs and legal principles enshrined in it form the basis of traffic law in a majority of places.
An alternative convention called the SADC-RTSM, provided by the Southern African Development Community (SADC), is used by ten countries in southern Africa. Many of the rules and principles of the SADC-RTSM are similar to those of the Vienna Convention.
In the United States, signs are based on the US Federal Highway Administration's Manual on Uniform Traffic Control Devices. Signs in the MUTCD are often more text-oriented, though some signs do use pictograms as well. Canada and Australia have road signs based substantially on the MUTCD. In South America, Ireland, several Asian countries (Cambodia, Japan, Thailand, Malaysia and Indonesia) and New Zealand, road signage is influenced by both the Vienna Convention and MUTCD. In Central America, road signs are heavily influenced by MUTCD and based on the Manual Centroamericano de Dispositivos Uniformes para el Control del Transito, a Central American Integration System (SICA) equivalent to the US MUTCD.

## Rules
### Road signs

In article 2 the convention classes all road signs into a number of categories (A–H):
* A: Danger warning signs
* B: Priority signs
* C: Prohibitory or restrictive signs
* D: Mandatory signs
* E: Special regulation signs
* F: Information, facilities, or service signs
* G: Direction, position, or indication sign
* H: Additional panels
The convention then lays out precise colours, sizes, and shapes for each of these classes of sign:
| Class of sign | Shape | Ground | Border | Size | Symbol | Examples |
| Danger warning sign | Equilateral triangle | White or yellow | Red | 0.9 m (large), 0.6 m (small) | Varies; Black or dark blue | |
| Danger warning sign | Diamond | Yellow | Black | 0.6 m (large), 0.4 m (small) | Varies; Black or dark blue | |
| Priority signs |||||||
| Give Way sign | Inverted equilateral triangle | White or yellow | Red | 0.9 m (large), 0.6 m (small) | None | |
| Stop sign | Octagon | Red | White | 0.9 m (large), 0.6 m (small) | Stop$^†$ written in white | |
| Stop sign | Circular | White or yellow | Red | 0.9 m (large), 0.6 m (small) | Stop$^†$ written in black or dark blue inside red inverted triangle | |
| Priority road | Diamond | White | Black | 0.5 m (large), 0.35 m (small) | Yellow or orange square | |
| End of priority road | Diamond | White | Black | 0.5 m (large), 0.35 m (small) | Yellow or orange square with black or grey diagonal lines crossing the sign | |
| Priority for oncoming traffic | Circular | White or yellow | Red | Unspecified | Black arrow indicating direction with priority, red arrow indicating direction without | |
| Priority over oncoming traffic | Rectangle | Blue | None | Unspecified | White arrow indicating direction with priority, red arrow indicating direction without | |
| Prohibitory signs |||||||
| Standard prohibitory | Circular | White or yellow | Red | 0.6 m (large), 0.4 m (small) | Varies; black or dark blue | |
| Parking prohibited | Circular | Blue | Red | 0.6 m (large), 0.2 m (small) | None | |
| Parking prohibited | Circular | White or yellow | Red | 0.6 m (large), 0.2 m (small) | Initial letter or ideogram to denote parking; black or dark blue | |
| Stopping prohibited | Circular | Blue | Red | 0.6 m (large), 0.4 m (small) | None | |
| End of prohibition | Circular | White or yellow | None | 0.6 m (large), 0.4 m (small) | Black or grey diagonal line | |
| Mandatory signs |||||||
| Standard mandatory | Circular | Blue | None, white | 0.6 m (large), 0.4 m (small), 0.3 m (very small) | Varies, white | |
| Standard mandatory | Circular | White or yellow | Red | 0.6 m (large), 0.4 m (small), 0.3 m (very small) | Varies, black or dark blue | |
| Special regulation signs |||||||
| All signs | Rectangular | Blue | Unspecified | Unspecified | Varies, white | |
| All signs | Rectangular | Light | Unspecified | Unspecified | Varies, Black | |
| Information, facilities or service signs |||||||
| All signs | Unspecified | Blue or green | Unspecified | Unspecified | Varies, on white or yellow rectangle | |
| Direction, position or indication signs |||||||
| Informative signs | Rectangular, sometimes with arrowhead | Light | Unspecified | Unspecified | Varies, dark | |
| Informative signs | Rectangular, sometimes with arrowhead | Dark | Unspecified | Unspecified | Varies, light | |
| Motorways | Rectangular | Blue or green | Unspecified | Unspecified | Varies, white | |
| Temporary | Rectangular | Yellow or orange | Unspecified | Unspecified | Varies, black | |
| Additional panels |||||||
| All panels | Unspecified | White, blue or yellow | Black, blue or red | Unspecified | Varies, black or dark blue | |
| All panels | Unspecified | Black, red or dark blue | White, blue or yellow | Unspecified | Varies, white, blue or yellow | |
| Class of sign | Shape | Ground | Border | Size | Symbol | Examples |
$^†$ May be written in English or the national language
It also specifies the symbols and pictograms which may be used, and the orientations in which they may be used. When more than one is available, the same one must be used nationally. All signs, except for those that do not apply at night, must be reflective enough to be seen in darkness with headlights from a distance.

### Road markings

The convention also specifies road markings. All such markings must be less than 6 mm high, with cat's eye reflectors no more than 15 mm above the road surface. The road markings shall be white or yellow.
The length and width of markings varies according to purpose, although no exact figures for size are stated; roads in built up areas should use a broken line for lane division, while continuous lines must only be used in special cases, such as reduced visibility or narrowed carriageways.
All words painted on the road surface should be either of place names, or of words recognisable in most languages, such as "Stop" or "Taxi".

### Traffic lights

The Convention specifies the colours for traffic lights and their meanings, and places and purposes lights may be used for, like so:
| Type | Shape | Colour | Position | Meaning |
| Non-flashing | Plain | Green | At intersection, entrance to tunnel or bridge | Proceed |
| Non-flashing | Plain | Amber | At intersection, level crossing, swing bridge, airport, fire station or ferry terminal | Stop if safe to do so |
| Non-flashing | Plain | Red | At intersection | Stop |
| Non-flashing | Plain | Red and amber | At intersection | Signal is about to change (usually to green) |
| Non-flashing | Arrow pointing left | Green | At intersection | Only traffic turning left may proceed |
| Non-flashing | Arrow pointing right | Green | At intersection | Only traffic turning right may proceed |
| Non-flashing | Arrow pointing upwards | Green | At intersection | Only traffic travelling straight ahead may proceed |
| Non-flashing | Arrow pointing downwards | Green | Above lane | Traffic may continue in lane |
| Non-flashing | Cross (×) | Red | Above lane | Traffic may not enter lane (lane closed) |
| Non-flashing | Arrow pointing diagonally downwards | Amber or white | Above lane | Lane closes shortly ahead, change lane in the direction of the arrow |
| Flashing | Plain | Double Red (alternating) | At level crossing, swing bridge, airport, fire station or ferry terminal | Stop |
| Flashing | Plain | Lunar white | At crossing | Proceed |
| Flashing | Plain | Amber (flashing) | Anywhere except intersection | Proceed with caution |
| Flashing | Plain | Amber (flashing) | At intersection | The priority is determined by Priority Route or Yield signs or if none of the above regular right of way rule. |
Red flashing lights may only be used at the locations specified above; any other use of the lights is in breach of the convention. Red lights must be placed on top when lights are stacked vertically, or on the side closest to oncoming traffic if stacked horizontally.

## Contracting parties

The convention has 71 state parties and 35 signatories (including acceding members) as of October 2022: Albania, Armenia, Austria, Azerbaijan, Bahrain, Belarus, Belgium, Benin, Bosnia and Herzegovina, Brazil, Bulgaria, Burundi, Central African Republic, Chile, Costa Rica, Côte d'Ivoire, Croatia, Cuba, Cyprus, Czechia, Democratic Republic of the Congo, Denmark, Ecuador, Estonia, Finland, France, Georgia, Germany, Ghana, Greece, Guyana, Holy See, Hungary, India, Indonesia, Iran, Iraq, Italy, Kazakhstan, Kuwait, Kyrgyzstan, Latvia, Liberia, Liechtenstein, Lithuania, Luxembourg, North Macedonia, Madagascar, Mexico, Moldova, Mongolia, Montenegro, Morocco, Myanmar, Netherlands, Nigeria, Norway, Pakistan, Paraguay, the Philippines, Poland, Portugal, Qatar, Romania, Russia, San Marino, Saudi Arabia, Senegal, Serbia, Seychelles, Sierra Leone, Slovakia, Slovenia, Spain, Sri Lanka, Suriname, Sweden, Switzerland, Tajikistan, Thailand, Tunisia, Turkmenistan, Uganda, Ukraine, United Arab Emirates, United Kingdom, Uzbekistan, Venezuela and Vietnam.
The only countries in Europe that are not parties to the convention are Andorra, Ireland, Iceland, Malta and Monaco.
Countries in Asia that are not parties to the convention are Afghanistan, Bangladesh, Malaysia, People's Republic of China (including Hong Kong and Macau), Republic of China (Taiwan), Israel, Japan, Jordan, Lebanon, North Korea, Oman, Palestine, Syria and Yemen. Cambodia, Laos, and South Korea are all signatories, but have yet to ratify the convention.
Other countries have not signed the convention; however, some have voluntarily adopted some Vienna convention signs.