Left- and right-hand traffic
Left-hand traffic and right-hand traffic are the practices, in bidirectional traffic, of keeping to the left side or to the right side of the road, respectively. They are fundamental to traffic flow, and are sometimes referred to as the rule of the road.
RHT is used in 165 countries and territories, with the remaining 75 countries and territories using LHT. Countries that use LHT account for about a sixth of the world's land area, with about a third of its population and a quarter of its roads. In 1919, 104 of the world's territories were LHT and an equal number were RHT. Between 1919 and 1986, 34 of the LHT territories switched to RHT.
Many LHT countries were formerly part of the British Empire, although many were not, such as Sweden, Japan, Thailand, Indonesia, Nepal and Suriname, among others. Conversely, many RHT countries were part of the French colonial empire.
In LHT traffic keeps left, and cars have the steering wheel on the right, putting the driver on the side closest to the centre of the road. Roundabouts circulate clockwise. In RHT everything is reversed: traffic keeps right, the driver sits on the left side of the car, and roundabouts circulate anticlockwise.
In most countries rail traffic follows the handedness of the roads, although many of the countries that switched road traffic from LHT to RHT did not switch their trains. Boat traffic on rivers is effectively RHT. Boats are traditionally piloted from the starboard side to facilitate priority to the right.
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. About 90 percent of people are right handed, 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 documented evidence to back either claim.Europe
One of the first references in England to requiring traffic direction was an order by the London Court of Aldermen in 1669, requiring a man to be posted on London Bridge to ensure that "all cartes going to keep on the one side and all cartes coming to keep on the other side". It later was legislated as the London Bridge Act 1765, which required that "all carriages passing over the said bridge from London shall go on the east side thereof" – those going south to remain on the east, ie the left-hand side by direction of travel. This may represent the first statutory requirement for LHT.A frequently-heard story is that Napoleon changed the custom from LHT to RHT in France and the countries he conquered after the French Revolution. Scholars who have looked for documentary evidence of this story have found none, and it should be assumed a myth unless contemporary sources surface. In 1827, long after Napoleon's reign, Edward Planta wrote that, in Paris, "The coachmen have no established rule by which they drive on the right or left of the road, but they cross and jostle one another without ceremony."
Rotterdam was LHT until 1917, 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. 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. Croatia-Slavonia switched on joining the Kingdom of Yugoslavia in 1918, although Istria and Dalmatia were already RHT. Nazi Germany introduced the switch in Czechoslovakia and Slovakia in 1938–1939. 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, and the 1903 Baedeker guide reported that the rule of the road varied by region. 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, as were the cities Milan, Turin, and Florence. In 1915, allied forces of World War I imposed LHT in areas of military operation, but this was revoked in 1918. Rome was reported by Goethe as LHT in the 1780s. 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. Finally, in 1923 Italian Duce Benito Mussolini decreed that all LHT areas would gradually transition to RHT. In spite of this, some Italian heavy commercial vehicles were right-hand drive until the traffic code was changed in 1959.
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.
, Sweden, on 3 September 1967
Sweden switched to RHT in 1967, having been LHT from about 1734 despite having land borders with RHT countries, and approximately 90% of cars being left-hand drive. 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 at 5 am. The accident rate then dropped sharply, but soon rose to near its original level. The day was known as Högertrafikomläggningen, or Dagen H for short.
When Iceland switched to RHT the following year, it was known as Hægri dagurinn or H-dagurinn. Most passenger cars in Iceland were already LHD.
The United Kingdom is LHT, but two of its overseas territories, Gibraltar and the British Indian Ocean Territory, are RHT. In the late 1960s, the British Department for Transport considered switching to RHT, but declared it unsafe and too costly for such a built-up nation. Road building standards, for motorways in particular, allow asymmetrically designed road junctions, where merge and diverge lanes differ in length.
Today, four countries in Europe continue to use LHT; they are all island nations: the United Kingdom, Republic of Ireland and Cyprus and Malta.
Africa
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, Sierra Leone, and Nigeria. Britain introduced LHT to the East Africa Protectorate, Rhodesia, and the Cape Colony. All of these have remained LHT. Sudan, formerly part of Anglo-Egyptian Sudan switched to RHT in 1973, as most of its neighbours were RHT countries, with the exception of Uganda and Kenya, but since the independence of South Sudan in 2011, all of its neighbours drive on the right. Despite it sharing land borders with two LHT countries, South Sudan has retained RHT.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 these areas 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 are RHT but are considering switching to LHT.
North America
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 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. The first keep-right law for driving in the United States was passed in 1792 and applied to the Philadelphia and Lancaster Turnpike. New York formalized RHT in 1804, New Jersey in 1813, and Massachusetts in 1821. Today the United States is RHT except the United States Virgin Islands, which is LHT like many neighbouring islands.Some special-purpose vehicles in the United States, including certain postal service trucks, garbage trucks, and parking enforcement vehicles, are built with the driver's seat on the right for safer and easier access to the curb. A common example is the Grumman LLV used nationwide by the United States Postal Service.
As former French colonies, the provinces of Quebec and Ontario were always RHT. The province of British Columbia changed to RHT in stages from 1920 to 1923. New Brunswick, Nova Scotia, and Prince Edward Island, changed to RHT in 1922, 1923, and 1924 respectively. Newfoundland, then a British colony, changed to RHT in 1947, two years before joining Canada.
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. However, most vehicles in The Bahamas, British Virgin Islands, Cayman Islands, Turks and Caicos Islands and United States Virgin Islands are left hand drive.
Asia
LHT was introduced by the British in British India, British Malaya and British Borneo, and British Hong Kong. All are still LHT except Myanmar, which switched to RHT in 1970, although much of its infrastructure is still geared to LHT. Most cars are used RHD vehicles imported from Japan. Afghanistan was LHT until the 1950s, in line with neighbouring British India and later Pakistan.LHT was introduced by the Portuguese Empire in Portuguese Macau and Portuguese 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 switched to RHT along with Portugal in 1928 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.
The Philippines was mostly LHT during its Spanish and American colonial periods, as well as during the Commonwealth era. During the Japanese occupation, the Philippines remained LHT, also because LHT had been required by the Japanese; 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.
Japan was never part of the British Empire, but its traffic also drives on the left. Although the origin of this habit goes back to the Edo period, 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, with all trains and trams being driven on the left-hand side. However, it took another half century until 1924, in which left-hand traffic was clearly written in law.
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. The conversion operation was known as 730. 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 Laos and Cambodia. In Cambodia, RHD cars, many of which were smuggled from Thailand, were banned from 2001, even though they accounted for 80% of vehicles in the country.
Oceania
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, those being Nauru and Papua New Guinea.Samoa, a former German colony, had been RHT for more than a century, but switched to LHT in 2009, This made it the first territory in almost 30 years to change sides. The move was legislated in 2008 to allow Samoans to use cheaper right-hand drive 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 to try to protest against the change, with the latter launching a legal challenge, and in April 2008 an estimated 18,000 people attended demonstrations against it. The motor industry was also opposed, as 14,000 of Samoa's 18,000 vehicles were designed for RHT and the government refused to meet the cost of conversion. After months of preparation, the switch from right to left happened in an atmosphere of national celebration. There were no reported incidents. 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. The change coincided with more restrictive enforcement of speeding and seat-belt laws. That day and the following day were declared public holidays, to reduce traffic. The change included a three-day ban on alcohol sales, while police mounted dozens of checkpoints, warning drivers to drive slowly.
South America
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. Other Central and South American countries that later switched from LHT to RHT include Argentina, Chile, Panama, Paraguay, and Uruguay.Suriname, along with neighbouring Guyana, are the only two remaining LHT countries in South America.
Potential future shifts
and Burundi, former Belgian colonies in Central Africa, are RHT but are considering switching to LHT like neighbouring members of the East African Community. 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. In 2014, an internal report by consultants to the Ministry of Infrastructure recommended a switch to LHT. In 2015, the ban on RHD vehicles was lifted; RHD trucks from neighbouring countries cost $1000 less than LHD models imported from Europe.Changing sides at borders
Although many LHT jurisdictions are on islands, there are cases where vehicles may be driven from LHT across a border into a RHT area. Such borders are mostly located in Africa and southern Asia. The Vienna Convention on Road Traffic regulates the use of foreign registered vehicles in the 78 countries that have ratified it.LHT Thailand has three RHT neighbours: Cambodia, Laos, and Myanmar. Most of its borders use a simple traffic light to do the switch, but there are also interchanges which enable the switch while keeping up a continuous flow of traffic.
There are four road border crossing points between Hong Kong and Mainland China. In 2006, the daily average number of vehicle trips recorded at Lok Ma Chau was 31,100. The next largest is Man Kam To, where there is no changeover system and the border roads on the mainland side Wenjindu intersect as one-way streets with a main road.
The Takutu River Bridge is the only border in the Americas, and the New World, where traffic changes sides.
Although the United Kingdom is separated from Continental Europe by the English Channel, the level of cross-Channel traffic is very high; the Channel Tunnel alone carries 3.5 million vehicles per year by the Eurotunnel Shuttle between the UK and France.
Road vehicle configurations
Steering wheel position
In RHT jurisdictions, vehicles are configured with LHD, with the steering wheel on the left side. In LHT jurisdictions, the reverse is true. The driver's side, the side closest to the centre of the road, is sometimes called the offside, while the passenger side, the side closest to the side of the road, is sometimes called the nearside.Most windscreen wipers are designed to clear the driver's side better and have a longer blade on the driver's side and wipe up from the passenger side to the driver's side. Thus on LHD configurations, they wipe up from right to left, viewed from inside the vehicle, and do the opposite on RHD vehicles.
Regardless of steering wheel position, the turn signal lever is on the side closer to the driver's door, except in some European RHD vehicles where it is on the opposite side.
Historically there was less consistency in the relationship of the position of the driver to the handedness of traffic. Most American cars produced before 1910 were RHD. In 1908 Henry Ford standardised the Model T as LHD in RHT America, arguing that with RHD and RHT, the passenger was obliged to "get out on the street side and walk around the car" and that with steering from the left, the driver "is able to see even the wheels of the other car and easily avoids danger." By 1915 other manufacturers followed Ford's lead, due to the popularity of the Model T.
In specialised cases, the driver will sit on the nearside, or kerbside. Examples include:
- Where the driver needs a good view of the nearside, e.g. street sweepers, or vehicles driven along unstable road edges.
- Where it is more convenient for the driver to be on the nearside, e.g. delivery vehicles. The Grumman LLV postal delivery truck is widely used with RHD configurations in RHT North America. Some Unimogs are designed to switch between LHD and RHD to permit operators to work on the more convenient side of the truck.
Headlamps and other lighting equipment
Most low-beam headlamps produce an asymmetrical light suitable for use on only one side of the road. Low beam headlamps in LHT jurisdictions throw most of their light forward-leftward; those for RHT throw most of their light forward-rightward, thus illuminating obstacles and road signs while minimising glare for oncoming traffic.In Europe, headlamps approved for use on one side of the road must be adaptable to produce adequate illumination with controlled glare for temporarily driving on the other side of the road,. This may be achieved by affixing masking strips or prismatic lenses to a part of the lens or by moving all or part of the headlamp optic so all or part of the beam is shifted or the asymmetrical portion is occluded. Some varieties of the projector-type headlamp can be fully adjusted to produce a proper LHT or RHT beam by shifting a lever or other movable element in or on the lamp assembly. Some vehicles adjust the headlamps automatically when the car's GPS detects that the vehicle has moved from LHT to RHT and vice versa.
Rear fog lamps
In the European Union, vehicles must be equipped with one or two red rear fog lamps. A single rear fog lamp must be located between the vehicle's longitudinal centreline and the outer extent of the driver's side of the vehicle.Crash testing differences
An Australian news source reports that some RHD cars imported to that country did not perform as well on crash tests as the LHD versions, although the cause is unknown, and may be due to differences in testing methodology.Rail traffic
In most countries, rail traffic travels on the same side as road traffic. However, in many cases, railways were built using LHT British technology and, while road traffic switched to RHT, rail remained LHT. Examples include: Argentina, Belgium, Bolivia, Cambodia, Chile, Egypt, France, Iraq, Israel, Italy, Laos, Monaco, Myanmar, Nigeria, Peru, Portugal, Senegal, Slovenia, Sweden, Switzerland, Taiwan, Tunisia, Venezuela, and Yemen. In Indonesia it is the reverse. France is mainly LHT for trains, except for the classic lines in Alsace-Lorraine, which belonged to Germany from 1870 to 1918, when the railways were built, along with most metro systems. China is basically LHT for long-distance trains and RHT for metro systems. Spain, which is RHT for railways has LHT for metros in Madrid and Bilbao. Metros and light rail sides of operation vary, and might not match railways or roads in their country. Trams generally operate at the same side as other road traffic because they frequently share roads.Boat traffic
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, 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, and in aircraft with side-by-side cockpit seating, the pilot-in-command traditionally occupies the left seat.