Left- and right-hand traffic

Countries by handedness of road traffic, c. 2019
  Left-hand traffic
  Right-hand traffic

Left-hand traffic (LHT) and right-hand traffic (RHT) are the practice, in bidirectional traffic, of keeping to the left side or to the right side of the road, respectively. A fundamental element to traffic flow, it is sometimes referred to as the rule of the road.[1]

RHT is used in 165 countries and territories, with the remaining 75 countries and territories using LHT.[2] Countries that use LHT account for about a sixth of the world's area with about a third of its population and a quarter of its roads.[3] In 1919, 104 of the world's territories were LHT and an equal number were RHT. Between 1919 and 1986, thirty-four of the LHT territories switched to RHT.[4]

Many LHT countries were formerly part of the British Empire, although some were not, such as Japan, Thailand, Indonesia, and Suriname. Conversely, many RHT countries were part of the French colonial empire.

For rail transport, LHT predominates in Western Europe (except Germany, Denmark, Austria, Spain, and the Netherlands), Latin America (except Mexico), and in countries formerly in the British and French Empires, whereas North American and central and eastern European train services operate RHT.[citation needed]

Boats are traditionally piloted from starboard to facilitate priority to the right

According to the International Regulations for Preventing Collisions at Sea, water traffic is effectively RHT: a vessel proceeding along a narrow channel must keep to starboard (the right-hand side), and when two power-driven vessels are meeting head-on both must alter course to starboard also. For aircraft the US Federal Aviation Regulations suggest RHT principles, both in the air and on water.[5]

In LHT vehicles keep left, and cars are RHD (right-hand drive) with the steering wheel on the right-hand side and the driver sitting on the offside or side closest to the centre of the road. The passenger sits on the nearside, closest to the curb. Roundabouts circulate clockwise. In RHT everything is reversed: cars keep right, the driver sits on the left side of the car, and roundabouts circulate counterclockwise.

History

Historically, many places kept left, while many others kept right, often within the same country. There are many myths which attempt to explain why one or the other is preferred.[6] About 90 per cent of people are right handed,[7] and many explanations reference this. Horses are traditionally mounted from the left, and led from the left, with the reins in the right hand. So people walking horses might use RHT, to keep the animals separated. Also referenced is the need for pedestrians to keep their swords in the right hand and pass on the left as in LHT, for self-defence. It has been suggested that wagon-drivers whipped their horses with their right hand, and thus sat on the left hand side of the wagon, as in RHT. It has been written that in the year 1300, Pope Boniface VIII directed pilgrims to keep left, however it has also been written that he directed them to keep to the right, and there is no documentary evidence to back either claim.[6]

Europe

Border between Sweden and Norway in 1934
Traffic moves from left to right in Stockholm, Sweden, on 3 September 1967

The first reference in English law to LHT was in 1756, with regard to London Bridge.[8]

After the French Revolution, all traffic in France kept right.[8]

Rotterdam was LHT until 1917,[9] although the rest of the Netherlands was RHT.

Russia completely switched to RHT in the last days of the Tsars in February 1917.

After the Austro-Hungarian Empire broke up, the resulting countries gradually changed to RHT. In Austria, Vorarlberg switched in 1921, North Tyrol in 1930, Carinthia and East Tyrol in 1935, and the rest of the country in 1938.[10] In Romania, Transylvania, the Banat and Bukovina were LHT until 1919, while Wallachia and Moldavia were already RHT. Partitions of Poland belonging to the German Empire and the Russian Empire were RHT, while the former Austrian Partition changed in the 1920s.[11] Croatia-Slavonia switched on joining the Kingdom of Yugoslavia in 1918, although Istria and Dalmatia were already RHT.[12] Nazi Germany introduced the switch in Czechoslovakia and Slovakia in 1938–1939.[13][14] West Ukraine was LHT, but the rest of Ukraine, having been part of the Russian Empire, was RHT.

In Italy it had been decreed in 1901 that each province define its own traffic code, including the handedness of traffic,[15] and the 1903 Baedeker guide reported that the rule of the road varied by region.[6] For example, in Northern Italy, the provinces of Brescia, Como, Vicenza, and Ravenna were RHT while nearby provinces of Lecco, Verona, and Varese were LHT,[15] as were the cities Milan, Turin, and Florence.[6] In 1915, allied forces of World War I imposed LHT in areas of military operation, but this was revoked in 1918. The situation was similar in Southern Italy with Rome being reported by Goethe as LHT as early as the late 1700s. Naples was also LHT although surrounding areas were often RHT. In cities LHT was considered safer since pedestrians, accustomed to keeping right, could better see oncoming vehicular traffic.[15] Finally, in 1923 totalitarian ruler Benito Mussolini decreed that all LHT areas would gradually transition to RHT.[15]

Portugal switched to RHT in 1928.

Finland, formerly part of LHT Sweden, switched to RHT in 1858 as the Grand Duchy of Finland by Russian decree.[16]

Sweden switched to RHT in 1967, having been LHT from about 1734[17] despite having land borders with RHT countries, and approximately 90% of cars being left-hand drive (LHD).[18] A referendum in 1955 overwhelmingly rejected a change to RHT, but a few years later the government ordered it, and it occurred on Sunday, 3 September 1967[19] at 5 am. The accident rate then dropped sharply,[20] but soon rose to near its original level.[21] The day was known as Högertrafikomläggningen, or Dagen H for short. When Iceland switched the following year, it was known as Hægri dagurinn or H-dagurinn ("The H-Day").[22] Most passenger cars in Iceland were already LHD.

The United Kingdom is LHT, but its overseas territories of Gibraltar and British Indian Ocean Territory are RHT. In the late 1960s, the UK Department for Transport considered switching to RHT, but declared it unsafe and too costly for such a built-up nation.[23] Road building standards, for motorways in particular, allow asymmetrically designed road junctions, where merge and diverge lanes differ in length.[24]

Today, four countries in Europe continue to use LHT; they are all island nations and formerly parts of the British Empire: the United Kingdom, Cyprus, Republic of Ireland, and Malta.

Africa

RHT roundabout sign

Egypt was conquered by Napoleon and it kept RHT even after it became a British dependency.

LHT was introduced in British West Africa. All of the countries formerly part of this colony border with former French RHT jurisdictions and have switched to RHT since decolonization. These include Ghana, Gambia,[25] Sierra Leone, and Nigeria. Britain introduced LHT to the East Africa Protectorate (now Kenya, Tanzania and Uganda), Rhodesia, and the Cape Colony (now Zambia, Zimbabwe and South Africa). All of these have remained LHT. Sudan, formerly part of Anglo-Egyptian Sudan switched to RHT in 1973, as it is surrounded by neighbouring RHT countries.

The Portuguese Empire, then LHT, introduced LHT to Portuguese Mozambique and Portuguese Angola. Although Portugal itself switched to RHT in 1928, Mozambique remained LHT as they have land borders with former British colonies. Other former Portuguese colonies in Africa including Portuguese Angola, Guinea-Bissau, São Tomé and Príncipe, and Cape Verde switched to RHT in 1928.

France introduced RHT in French West Africa and the Maghreb, where it is still used. Countries in this former colony include Mali, Mauritania, Ivory Coast, Burkina Faso, Benin, Niger, Morocco, Algeria, and Tunisia. Other French former colonies that are RHT include Cameroon, Central African Republic, Chad, Djibouti, Gabon, and the Republic of the Congo.

Rwanda and Burundi, former Belgian colonies in Central Africa, are RHT but are considering switching to LHT[26][27] like neighbouring members of the East African Community (EAC).[28] A survey in 2009 found that 54% of Rwandans favoured the switch. Reasons cited were the perceived lower costs of RHD vehicles, easier maintenance and the political benefit of harmonious traffic regulations with other EAC countries. The survey indicated that RHD cars were 16% to 49% cheaper than their LHD counterparts.[29] In 2014, an internal report by consultants to the Ministry of Infrastructure recommended a switch to LHT.[30] In 2015, the ban on RHD vehicles was lifted; RHD trucks from neighbouring countries cost $1000 less than LHD models imported from Europe.[31][32]

North America

Saint John, New Brunswick, circa 1898. Parts of Canada were LHT until the 1920s.

In what is now Canada, LHT was introduced by the British in British Columbia, which changed to RHT in stages from 1920 to 1923,[33][34] and New Brunswick, Nova Scotia, and Prince Edward Island, which changed in 1922, 1923, and 1924 respectively.[35] Newfoundland, then a British colony,[36] changed to RHT in 1947, two years before joining Canada.[37] Former parts of New France have always been RHT.[38]

In the early years of British colonisation of North America in 18th century, British driving customs were followed and the original Thirteen Colonies drove on the left. After declaring independence from the United Kingdom in 4 July 1776, however, they were anxious to cast off all remaining links with their British colonial past and gradually changed to right-hand driving, influenced by a number of factors, including gratitude for French help in the War of Independence, the views of those Americans with roots in continental Europe and specifically the influence of General Lafayette, the French liberal reformer. Incidentally, the influence of other European immigrants, especially the French, should not be underestimated.

In the late 1700s, traffic in the United States was RHT based on teamsters' use of large freight wagons pulled by several pairs of horses. The wagons had no driver's seat, so the (typically right-handed) postilion held his whip in his right hand and thus sat on the left rear horse. Seated on the left, the driver preferred that other wagons pass him on the left so that he could be sure to keep clear of the wheels of oncoming wagons.[39] The first keep-right law for driving in the United States was passed in 1792 and applied to the Philadelphia and Lancaster Turnpike.[40] New York formalized RHT in 1804, New Jersey in 1813 and Massachusetts in 1821.[41] Today the United States is RHT except the United States Virgin Islands,[42] which is LHT like many neighbouring islands.

Some postal service vehicles, garbage trucks, many parking enforcement vehicles and uncommon speciality vehicles in the United States are still being RHD.

In the West Indies, colonies and territories drive on the same side as their parent countries, except for the United States Virgin Islands. Many of the island nations are former British colonies and drive on the left, including Jamaica, Antigua and Barbuda, Barbados, Dominica, Grenada, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines, Trinidad and Tobago, and The Bahamas.

Asia

Vehicles entering and leaving Macau cross over each other at the Lotus Bridge.

LHT was introduced by the British in British India (now India, Pakistan, Myanmar, and Bangladesh), British Malaya (now Malaysia, Brunei and Singapore), and British Hong Kong. All are still LHT except Myanmar, which switched to RHT in 1970,[43] although much of its infrastructure is still geared to LHT. Most cars are used RHD vehicles imported from Japan.[44] Afghanistan was LHT until the 1950s, in line with neighbouring British India and later Pakistan.[45]

LHT was introduced by the Portuguese Empire in Portuguese Macau (now Macau) and Portuguese Timor (now East Timor). Both places are still LHT, despite Macau now being part of RHT China, requiring a right-to-left switching interchange at the Lotus Bridge which connects the two. East Timor shares the island of Timor with Indonesia, which is also LHT, although the former (then Portuguese Timor) switched to RHT along with Portugal in 1928[1] before changing back to LHT in 1976 during the Indonesian occupation of East Timor.

China is RHT except the Special Administrative Regions of Hong Kong and Macau. LHT was uniform in the 1930s, then the northern provinces were RHT. Nationalist China adopted RHT in 1946. This convention was preserved when the CCP took the mainland and the KMT retreated to Taiwan.

Both North Korea and South Korea switched to RHT in 1945 after liberation from Japanese colonial power.[citation needed]

The Philippines was mostly LHT during its Spanish[46] and American colonial periods,[47][48] as well as during the Commonwealth era.[49] During the Japanese occupation, the Philippines remained LHT,[50] also because LHT had been required by the Japanese;[51] but during the Battle of Manila, the liberating American forces drove their tanks to the right for easier facilitation of movement. RHT was formalised in 1945.[52]

Japan was never part of the British Empire, but its traffic also goes to the left. Although the origin of this habit goes back to the Edo period (1603-1868), it was not until 1872 that this unwritten rule became more or less official. That was the year when Japan’s first railway was introduced, built with technical aid from the British. Gradually, a massive network of railways and tram tracks was built, and of course all trains and trams drove on the left-hand side. Still, it took another half century till in 1924 left-side driving was clearly written in a law. In Japan, Post-World War II Okinawa was ruled by the United States Civil Administration of the Ryukyu Islands and was RHT. It was returned to Japan in 1972 but did not convert back to LHT until 1978.[53] The conversion operation was known as 730 (Nana-San-Maru, which refers to the date of the changeover, 30 July). Okinawa is one of few places to have changed from RHT to LHT in the late 1900s.

Vietnam became RHT as part of French Indochina, as did Cambodia. In the latter country, RHD cars, many of which were smuggled from Thailand, were banned from 2001, even though they accounted for 80% of vehicles in the country.[54]

Oceania

A sign on the Great Ocean Road, heavily visited by international tourists, reminding motorists to keep left in Australia.

Many former British colonies in the region have always been LHT, including Australia, New Zealand, Fiji, Kiribati, Solomon Islands, Tonga, and Tuvalu, as well as nations which were previously administered by Australia, being Nauru and Papua New Guinea.

Samoa, a former German colony, had been RHT for more than a century. It switched to LHT in 2009,[55] being the first territory in almost 30 years to switch.[56] The move was legislated in 2008 to allow Samoans to use cheaper right-hand drive (RHD) vehicles—which are better suited for left-hand traffic—imported from Australia, New Zealand or Japan, and to harmonise with other South Pacific nations. A political party, The People's Party, was formed by the group People Against Switching Sides (PASS) to try to protest against the change, with the latter launching a legal challenge,[57] and in April 2008 an estimated 18,000 people attended demonstrations against it.[58] The motor industry was also opposed, as 14,000 of Samoa's 18,000 vehicles are designed for RHT and the government has refused to meet the cost of conversion.[56] After months of preparation, the switch from right to left happened in an atmosphere of national celebration. There were no reported incidents.[3] At 05:50 local time, Monday 7 September, a radio announcement halted traffic, and an announcement at 6:00 ordered traffic to switch to LHT.[55] The change coincided with more restrictive enforcement of speeding and seat-belt laws.[59] That day and the following day were declared public holidays, to reduce traffic.[60] The change included a three-day ban on alcohol sales, while police mounted dozens of checkpoints, warning drivers to drive slowly.[3]

South America

Brazil was a colony of Portugal until the early 19th century and during this century and the early 20th century had mixed rules, with some regions still on LHT, switching these remaining regions to RHT in 1928, the same year Portugal switched sides.[61] Other Central and South American countries that later switched from LHT to RHT include Argentina, Chile, Panama,[62] Paraguay,[63] and Uruguay.

Suriname, along with neighbouring Guyana, are the only two remaining LHT countries in South America.[64]