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Speed limits on road traffic, as used in most countries, set the legal maximum speed at which
vehicles A vehicle (from la, vehiculum) is a machine that transports people or cargo. Vehicles include wagons, bicycles, motor vehicles (motorcycles, cars, trucks, buses, mobility scooters for disabled people), railed vehicles (trains, trams), ...
may travel on a given stretch of road. Speed limits are generally indicated on a
traffic sign Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones. Later, signs with directional arms were introduce ...
reflecting the maximum permitted speed - expressed as
kilometres per hour The kilometre per hour ( SI symbol: km/h; non-standard abbreviations: kph, km/hr) is a unit of speed, expressing the number of kilometres travelled in one hour. History Although the metre was formally defined in 1799, the term "kilometres per h ...
(km/h) and/or
miles per hour Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller cou ...
(mph). Speed limits are commonly set by the legislative bodies of national or provincial governments and enforced by national or regional
police The police are a Law enforcement organization, constituted body of Law enforcement officer, persons empowered by a State (polity), state, with the aim to law enforcement, enforce the law, to ensure the safety, health and possessions of citize ...
and judicial authorities. Speed limits may also be variable, or in some places nonexistent, such as on most of the
Autobahn The (; German plural ) is the federal controlled-access highway system in Germany. The official German term is (abbreviated ''BAB''), which translates as 'federal motorway'. The literal meaning of the word is 'Federal Auto(mobile) Track' ...
en in
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
. The first numeric speed limit for automobiles was the limit introduced in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
in 1861. the highest posted speed limit in the world is , applied on two
motorway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms ...
s in the UAE. Speed limits and safety distance are poorly enforced in the UAE, specifically on the
Abu Dhabi Abu Dhabi (, ; ar, أَبُو ظَبْيٍ ' ) is the Capital city, capital and List of cities in the United Arab Emirates, second-most populous city (after Dubai) of the United Arab Emirates. It is also the capital of the Emirate of Abu Dha ...
to
Dubai Dubai (, ; ar, wikt:دبي, دبي, translit=Dubayy, , ) is the List of cities in the United Arab Emirates#Major cities, most populous city in the United Arab Emirates (UAE) and the capital of the Emirate of Dubai, the most populated of the 7 ...
motorway - which results in dangerous traffic, according to a French-government travel-advisory. Additionally, "drivers often drive at high speeds ndunsafe driving practices are common, especially on inter-city highways. On highways, unmarked
speed bumps Speed bumps (also called traffic thresholds, speed breakers or sleeping policemen) are the common name for a class of traffic calming devices that use vertical deflection to slow motor-vehicle traffic in order to improve safety conditions. Varia ...
and drifting sand create additional hazards", according to an American-government travel-advisory. There are several reasons to regulate speed on roads. It is often done in an attempt to improve
road traffic safety Road traffic safety refers to the methods and measures used to prevent road users from being killed or seriously injured. Typical road users include pedestrians, cyclists, motorists, vehicle passengers, horse riders, and passengers of on-road ...
and to reduce the number of casualties from traffic collisions. The
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
(WHO) identified speed control as one of a number of steps that can be taken to reduce road casualties. As of 2021, the WHO estimates that approximately 1.3 million people die of road traffic crashes each year. Authorities may also set speed limits to reduce the environmental impact of road traffic (vehicle noise, vibration, emissions) or to enhance the safety of pedestrians, cyclists, and other road-users. For example, a draft proposal from Germany's National Platform on the Future of Mobility task force recommended a blanket 130 km/h (81 mph) speed limit across the Autobahnen to curb fuel consumption and carbon emissions. Some cities have reduced limits to as little as for both safety and efficiency reasons. However, some research indicates that changes in the speed limit may not always alter average vehicle speed. Lower speed-limits could reduce the use of over-engineered vehicles.


History

In western cultures, speed limits predate the use of motorized vehicles. In 1652, the American colony of New Amsterdam passed a law stating, "No wagons, carts or sleighs shall be run, rode or driven at a gallop." The punishment for breaking the law was "two pounds Flemish," the equivalent of US $50 in 2019. The ''1832'' ''Stage Carriage Act'' introduced the offense of endangering the safety of a passenger or person by "furious driving" in the United Kingdom (UK). A series of Locomotive Acts (in 1861, 1865 and 1878) created the first numeric speed limits for mechanically propelled vehicles in the UK; the 1861 Act introduced a UK speed limit of on open roads in town, which was reduced to in towns and in rural areas by the 1865 "Red Flag Act." The Locomotives on Highways Act 1896, which raised the speed limit to is celebrated by the annual
London to Brighton Veteran Car Run The London to Brighton Veteran Car Run is the world's longest-running motoring event, held on a course between London () and Brighton (), England. To qualify, participating cars must have been built before 1905. It is also the world's largest ...
. On 28 January 1896, the first person to be convicted of speeding is believed to be Walter Arnold of
East Peckham East Peckham is a village and civil parish in Kent, England on the River Medway. The parish covers the main village as well as Hale Street and Beltring. History The Domesday entry for East and West Peckham reads:- :'' The Archbishop himself h ...
, Kent, UK, who was fined 1
shilling The shilling is a historical coin, and the name of a unit of modern currencies formerly used in the United Kingdom, Australia, New Zealand, other British Commonwealth countries and Ireland, where they were generally equivalent to 12 pence ...
plus costs for speeding at . In 1901, Connecticut was the first state in the United States to impose a numerical speed limit for motor vehicles, setting the maximum legal speed to 12 mph in cities and 15 mph on rural roads. Speed limits then propagated across the United States; by 1930 all but 12 states had established numerical limits. In 1903, in the UK, the national speed limit was raised to ; however, as this was difficult to enforce due to the lack of
speedometer A speedometer or speed meter is a gauge that measures and displays the instantaneous speed of a vehicle. Now universally fitted to motor vehicles, they started to be available as options in the early 20th century, and as standard equipment f ...
s, the 1930 "Road Traffic Act" abolished speed limits entirely. In 1934, a new limit of was imposed in urban centers, and in July 1967, a national speed limit was introduced. In Australia, during the early 20th century, there were people reported for "furious driving" offenses. One conviction in 1905 cited a vehicle furiously driving when passing a
tram A tram (called a streetcar or trolley in North America) is a rail vehicle that travels on tramway tracks on public urban streets; some include segments on segregated right-of-way. The tramlines or networks operated as public transport ...
traveling at half that speed. In May 1934, the Nazi-era "Road Traffic Act" imposed the first nationwide speed limit in Germany. In the 1960s, in continental Europe, some speed limits were established based on the V85 speed, (so that 85% of drivers respect this speed). In 1974, Australian speed limits underwent metrication: the urban speed limit of was converted to 60 km/h; the rural speed limits of and were changed to and respectively. In 2010, Sweden defined the '' Vision Zero'' program, a multi-national
road traffic safety Road traffic safety refers to the methods and measures used to prevent road users from being killed or seriously injured. Typical road users include pedestrians, cyclists, motorists, vehicle passengers, horse riders, and passengers of on-road ...
project that aims to achieve a
highway A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks. In some areas of the United States, it is used as an equivalent term to controlled-access ...
system with no fatalities or serious injuries involving road traffic.


Regulations

Most countries use the
metric Metric or metrical may refer to: * Metric system, an internationally adopted decimal system of measurement * An adjective indicating relation to measurement in general, or a noun describing a specific type of measurement Mathematics In mathe ...
speed unit of kilometers per hour, while others, including the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
,
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
, and
Liberia Liberia (), officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to Guinea–Liberia border, its north, Ivory Coast to Ivory Coast� ...
, use speed limits given in
miles per hour Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller cou ...
. Although there have been discussions about a
switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...
to using metric units in countries' other systems (see
Metrication in the United Kingdom Metrication, the process of introducing the metric system of measurement in place of imperial units, has made steady progress in the United Kingdom since the mid-20th century but today remains equivocal and varies by context. Most of government, ...
and
Metrication in the United States Metrication (or metrification) is the process of introducing the International System of Units, also known as SI units or the metric system, to replace a jurisdiction's traditional measuring units. U.S. customary units have been defined in ...
), there are currently no proposals to change these laws.


Basic rule


Vienna Convention on Road Traffic

In countries bound by the Vienna Conventions on Road Traffic (1968 & 1977), Article 13 defines a basic rule for speed and distance between vehicles:


Reasonable speed

Most legal systems expect drivers to drive at a safe speed for the conditions at hand, regardless of posted limits. In the United Kingdom, and elsewhere in
common law In law, common law (also known as judicial precedent, judge-made law, or case law) is the body of law created by judges and similar quasi-judicial tribunals by virtue of being stated in written opinions."The common law is not a brooding omniprese ...
, this is known as the
reasonable man In law, a reasonable person, reasonable man, or the man on the Clapham omnibus, is a hypothetical person of legal fiction crafted by the courts and communicated through case law and jury instructions. Strictly according to the fiction, it is ...
requirement. The German Highway Code (''Straßenverkehrs-Ordnung'') section on speed begins with the statement (translated to English):
Any person driving a vehicle may only drive so fast that the car is under control. Speeds must be adapted to the road, traffic, visibility and weather conditions as well as the personal skills and characteristics of the vehicle and load.
In France, the law clarifies that even if the speed is limited by law and by local authority, the driver assumes the responsibility to control a vehicle's speed, and to reduce that speed in various circumstances (such as when overtaking a pedestrian or bicycle, individually or in a group; when overtaking a stopped convoy; when passing a transportation vehicle loading or unloading people or children; when the road does not appear clear, or risky; when visibility is low; when the road descends rapidly; when road sections are small, busy, or residential in nature; when approaching the top of a hill; when nearing a crossing where visibility is uncertain; when specific lights are used; or when overtaking animals. If drivers do not master their speed, or do not reduce it in such cases, they can be penalized. Other qualifying conditions include driving through fog, heavy rain, ice, snow, gravel, or when drivers encounter sharp corners, a blinding glare, darkness, crossing traffic, or when there is an obstructed view of orthogonal traffic—such as by road curvature, parked cars, vegetation, or snow banks—thus limiting the Assured Clear Distance Ahead (ACDA). In the United States, this requirement is referred to as the basic rule, as outlined by US federal government law (49 CFR 392.14), which applies in all states as permitted under the
commerce clause The Commerce Clause describes an enumerated power listed in the United States Constitution ( Article I, Section 8, Clause 3). The clause states that the United States Congress shall have power "to regulate Commerce with foreign Nations, and amon ...
and
due process clause In United States constitutional law, a Due Process Clause is found in both the Fifth and Fourteenth Amendments to the United States Constitution, which prohibits arbitrary deprivation of "life, liberty, or property" by the government except a ...
. The basic speed law is almost always supplemented by specific maximum or minimum limits but applies regardless. In California, for instance, Vehicle Code section 22350 states that "No person shall drive a vehicle upon a highway at speed greater than is reasonable ... and in no event at a speed which endangers the safety of persons or property". The reasonable speed may be different than the posted speed limit. ''Basic rule'' speed laws are statutory reinforcements of the centuries-old
common law In law, common law (also known as judicial precedent, judge-made law, or case law) is the body of law created by judges and similar quasi-judicial tribunals by virtue of being stated in written opinions."The common law is not a brooding omniprese ...
negligence Negligence (Lat. ''negligentia'') is a failure to exercise appropriate and/or ethical ruled care expected to be exercised amongst specified circumstances. The area of tort law known as ''negligence'' involves harm caused by failing to act as ...
doctrine as specifically applied to vehicular speed. Citations for violations of the basic speed law without a crash have sometimes been ruled unfairly vague or arbitrary, hence a violation of the
due process of law Due process of law is application by state of all legal rules and principles pertaining to the case so all legal rights that are owed to the person are respected. Due process balances the power of law of the land and protects the individual pers ...
, at least in the State of Montana. Even within states, differing jurisdictions (counties and cities) choose to prosecute similar cases with differing approaches.


Excessive speed

Consequential results of basic law violations are often categorized as ''excessive speed'' crashes; for example, the leading cause of crashes on German autobahns in 2012 fell into that category: 6,587 so-called "speed related" crashes claimed the lives of 179 people, which represented almost half (46.3%) of 387 autobahn fatalities in 2012. However, "excessive speed" does not necessarily mean the speed limit was exceeded, rather that police determined at least one party traveled too fast for existing conditions. Examples of conditions where drivers may find themselves driving too fast include wet roadways (due to rain, snow, or ice), reduced visibility (due to fog or "white out" snow), uneven roads, construction zones, curves, intersections, gravel roads, and heavy traffic. Per distance traveled, consequences of inappropriate speed are more frequent on lower speed, lower quality roads; in the United States, for example, the "speeding fatality rate for local roads is three times that for Interstates". For speed management a distinction can exist between ''excess speed'' which consists of driving in excess of the speed limit, and ''inappropriate speed'' which consists of going too fast for the conditions.


Maximum speed limits

Most countries have a legally assigned numerical maximum speed limit which applies on all roads when no other speed limit indications are present; lower speed limits are often shown on a sign at the start of the restricted section, although the presence of streetlights or the physical arrangement of the road may sometimes also be used instead. A posted speed limit may only apply to that road or to all roads beyond the sign that defines them depending on local laws. The speed limit is commonly set at or below the 85th
percentile In statistics, a ''k''-th percentile (percentile score or centile) is a score ''below which'' a given percentage ''k'' of scores in its frequency distribution falls (exclusive definition) or a score ''at or below which'' a given percentage fall ...
operating speed (being the speed which no more than 15% of traffic exceeds), and in the US is frequently set below that speed. Thus, if the 85th percentile operating speed as measured by a "Traffic and Engineering Survey" exceeds the design speed, legal protection is given to motorists traveling at such speeds (design speed is "based on conservative assumptions about the driver, the vehicle, and roadway characteristics"). The theory behind the 85th percentile rules is that, as a policy, most citizens should be deemed reasonable and prudent, and limits must be practical to enforce. However, there are some circumstances where motorists do not tend to process all the risks involved, and as a mass, choose a poor 85th percentile speed. This rule, in practice, is a process for "voting the speed limit" by driving, in contrast to delegating the speed limit to an engineering expert. The maximum speed permitted by statute, as posted, is normally based on ideal driving conditions and the basic speed rule always applies. Violation of the statute generally raises a
rebuttable presumption In common law and civil law, a rebuttable presumption (in Latin, ''praesumptio iuris tantum'') is an assumption made by a court that is taken to be true unless someone proves otherwise. For example, a defendant in a criminal case is presumed i ...
of negligence. On international European roads, speed should be taken into account during the design stage.


Minimum speed limits

Some roads also have minimum speed limits, usually where slow speeds can impede traffic flow or be dangerous. The use of minimum speed limits is not as common as maximum speed limits, since the risks of speed are less common at lower speeds. In some jurisdictions, laws requiring a minimum speed are primarily centered around red-light districts or similar areas, where they may colloquially be referred to as ''kerb crawling laws''.


Middle speed limits

Traffic rules limiting only middle speeds are rare. One such example exists on the
ice road An ice road or ice bridge is a human-made structure that runs on a frozen water surface (a river, a lake or a sea water expanse).Masterson, D. and Løset, S., 2011, ISO 19906: Bearing capacity of ice and ice roads, Proceedings of the 21st Inte ...
s in
Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, an ...
, where it is advised to avoid driving at the speed of 25–40 km/h (16–25 mph) as the vehicle may create resonance that may in turn induce the breaking of ice. This means that two sets of speeds are allowed: under and between 40–70 km/h (25–43 mph).


Variable speed limits

In Germany, the first known experiments with variable speed limit signs took place in 1965 on a 30 kilometer stretch of German motorway, the A8 between
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the third-largest city in Germany, after Berlin and ...
and the border city of
Salzburg Salzburg (, ; literally "Salt-Castle"; bar, Soizbuag, label=Austro-Bavarian) is the fourth-largest city in Austria. In 2020, it had a population of 156,872. The town is on the site of the Roman settlement of ''Iuvavum''. Salzburg was founded ...
, Austria. Mechanically variable message signs could display speeds of 60, 80 and 100 km/h, as well as text indicating a "danger zone" or "accident". Personnel monitored traffic using video technology and manually controlled the signage. Beginning in the 1970s, additional advanced traffic control systems were put into service. Modern motorway control systems can work without human intervention using various types of sensors to measure traffic flow and weather conditions. In 2009, 1,300 kilometers (810 miles) of German motorways were equipped with such systems. In the United States, heavily traveled portions of the
New Jersey Turnpike The New Jersey Turnpike (NJTP) is a system of controlled-access highways in the U.S. state of New Jersey. The turnpike is maintained by the New Jersey Turnpike Authority (NJTA).The Garden State Parkway, although maintained by NJTA, is not cons ...
began using variable speed limit signs in combination with variable message signs in the late 1960s. Officials can adjust the speed limit according to weather, traffic conditions, and construction. More typically, variable speed limits are used on remote stretches of highway in the United States in areas with extreme changes in driving conditions. For example, variable limits were introduced in October 2010 on a stretch of
Interstate 80 Interstate 80 (I-80) is an east–west transcontinental freeway that crosses the United States from downtown San Francisco, California, to Teaneck, New Jersey, in the New York metropolitan area. The highway was designated in 1956 as one ...
in
Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to t ...
, replacing the winter season speed reduction from that had been in place since 2008. This Variable Speed Limit system has been proven effective in terms of reducing crash frequency and road closures. Similarly,
Interstate 90 Interstate 90 (I-90) is an east–west transcontinental freeway and the longest Interstate Highway in the United States at . It begins in Seattle, Washington, and travels through the Pacific Northwest, Mountain West, Great Plains, Midwest, and ...
at
Snoqualmie Pass Snoqualmie Pass is a mountain pass that carries Interstate 90 (I-90) through the Cascade Range in the U.S. state of Washington. The pass summit is at an elevation of , on the county line between Kittitas County and King County. Snoqualmie P ...
and other mountain passes in Washington State have variable speed limits as to slow traffic in severe winter weather. As a response to fog-induced chain-reaction collisions involving 99 vehicles in 1990, a variable speed limit system covering of
Interstate 75 Interstate 75 (I-75) is a major north–south Interstate Highway in the Great Lakes and Southeastern regions of the United States. As with most Interstates that end in 5, it is a major cross-country, north–south route, traveling from St ...
in
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. Tennessee is the List of U.S. states and territories by area, 36th-largest by ...
was implemented in fog-prone areas around the Hiwassee River. The
Georgia Department of Transportation The Georgia Department of Transportation (GDOT) is the organization in charge of developing and maintaining all state and federal roadways in the U.S. state of Georgia. In addition to highways, the department also has a limited role in develop ...
installed variable speed limits on part of Interstate 285 around
Atlanta Atlanta ( ) is the capital and most populous city of the U.S. state of Georgia. It is the seat of Fulton County, the most populous county in Georgia, but its territory falls in both Fulton and DeKalb counties. With a population of 498,7 ...
in 2014. These speeds can be as low as but are generally set to . In 2016, the
Oregon Department of Transportation The Oregon Department of Transportation (ODOT) is a department of the state government of the U.S. state of Oregon responsible for systems of transportation. It was first established in 1969. It had been preceded by the Oregon State Highway Depart ...
installed a variable speed zone on a 30-mile stretch of Interstate 84 between
Baker City Baker City is a city in and the county seat of Baker County, Oregon, United States. It was named after Edward D. Baker, the only U.S. Senator ever killed in military combat. The population was 10,099 at the time of the 2020 census. History Pla ...
and Ladd Canyon. The new electronic signs collect data regarding temperature, skid resistance, and average motorist speed to determine the most effective speed limit for the area before presenting the limit on the sign. This speed zone was scheduled to be activated November 2016.
Ohio Ohio () is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Of the List of states and territories of the United States, fifty U.S. states, it is the List of U.S. states and territories by area, 34th-l ...
established variable speed limits on three highways in 2017, then in 2019 granted the authority to the
Ohio Department of Transportation The Ohio Department of Transportation (ODOT; ) is the administrative department of the Ohio state government responsible for developing and maintaining all state and U.S. roadways outside of municipalities and all Interstates except the Ohio T ...
to establish variable limits on any of its highways. In the United Kingdom, a variable speed limit was introduced on part of the
M25 motorway The M25 or London Orbital Motorway is a major road encircling most of Greater London. The motorway is one of the most important roads in the UK and one of the busiest. Margaret Thatcher opened the final section in 1986, making the M25 the lon ...
in 1995, on the busiest section from junction 10 to 16. Initial results suggested savings in journey times, smoother-flowing traffic, and a decrease in the number of crashes; the scheme was made permanent in 1997. However, a 2004 National Audit Organisation report noted that the business case was unproved; conditions at the site of the Variable Speed Limits trial were not stable before or during the trial, and the study was deemed neither properly controlled nor reliable. Since December 2008 the upgraded section of the M1 between the M25 and
Luton Luton () is a town and unitary authority with borough status, in Bedfordshire, England. At the 2011 census, the Luton built-up area subdivision had a population of 211,228 and its built-up area, including the adjacent towns of Dunstable an ...
has had the capability for variable speed limits. In January 2010 temporary variable speed cameras on the M1 between J25 and J28 were made permanent. New Zealand introduced variable speed limits in February 2001. The first installation was on the
Ngauranga Gorge The Ngauranga Gorge is in the Wellington Region of New Zealand. State Highway 1 runs through the gorge, a vital link between central Wellington City and its northern suburbs and Porirua City and the Kapiti Coast; it is the main route north out o ...
section of the dual carriageway on State Highway 1, characterized by steep terrain, numerous bends, high traffic volumes, and a higher than average accident rate. The speed limit is normally .
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
undertook a short-term experiment in 2006, with a variable limit configuration that could increase statutory limits under the most favorable conditions, as well as reduce them. In June 2006, a stretch of motorway was configured with variable speed limits that could increase the general Austrian motorway limit of . Then Austrian Transport Minister
Hubert Gorbach Hubert Gorbach (born 27 July 1956) is an Austrian politician and a member of the Alliance for the Future of Austria (BZÖ). Until April 2005, he was a leading member in the Freedom Party. Born in Vorarlberg, he was vice-governor (german: Landes ...
called the experiment "a milestone in European transport policy-despite all predictions to the contrary"; however, the experiment was discontinued.


Roads without speed limits

Just over half of the
German autobahns The (; German plural ) is the federal controlled-access highway system in Germany. The official German term is (abbreviated ''BAB''), which translates as 'federal motorway'. The literal meaning of the word is 'Federal Auto(mobile) Track' ...
have only an advisory speed limit (a '' Richtgeschwindigkeit''), 15% have temporary speed limits due to weather or traffic conditions, and 33% have permanent speed limits, according to 2008 estimates. The advisory speed limit applies to any road in Germany outside of towns which is either a dual carriageway or features at least two lanes per direction, regardless of its classification (e.g. Autobahn, Federal Highway, State Road, etc.), unless there is a speed limit posted, although it is less common for non-autobahn roads to be unrestricted. All other roads in Germany outside of towns, regardless of classification, do have a general speed limit of 100 km/h, which is usually reduced to 80 km/h at Allée-streets (roads bordered by trees or bushes on one or both sites). Travel speeds are not regularly monitored in Germany; however, a 2008 report noted that on the autobahn in Niemegk (between Leipzig and Berlin) "significantly more than 60% of road users exceed ndmore than 30% of motorists exceed ". Measurements from the state of
Brandenburg Brandenburg (; nds, Brannenborg; dsb, Bramborska ) is a state in the northeast of Germany bordering the states of Mecklenburg-Vorpommern, Lower Saxony, Saxony-Anhalt, and Saxony, as well as the country of Poland. With an area of 29,480 squ ...
in 2006 showed average speeds of on a 6-lane section of autobahn in free-flowing conditions. Prior to
German reunification German reunification (german: link=no, Deutsche Wiedervereinigung) was the process of re-establishing Germany as a united and fully sovereign state, which took place between 2 May 1989 and 15 March 1991. The day of 3 October 1990 when the Ge ...
in 1990, accident reduction programs in eastern German states were primarily focused on restrictive traffic regulation. Within two years of reunification, the availability of high-powered vehicles and a 54% increase in motorized traffic led to a doubling of annual traffic deaths, despite "interim arrangements
hich Ij ( fa, ايج, also Romanized as Īj; also known as Hich and Īch) is a village in Golabar Rural District, in the Central District of Ijrud County, Zanjan Province, Iran Iran, officially the Islamic Republic of Iran, and also ...
involved the continuation of the speed limit of on autobahns and of outside cities". An extensive program of the four ''E''s (enforcement, education, engineering, and emergency response) brought the number of traffic deaths back to pre-unification levels after a decade of effort, while traffic regulations were conformed to western standards (e.g., freeway advisory limit, on other rural roads). Rural roads on the Isle of Man have no speed limits on many rural roads; a 2004 proposal to introduce general speed limits of 60 mph and 70 mph on Mountain Road, for safety reasons, was not pursued following consultation. Measured travel speeds on the island are relatively low. The Indian states of
Andhra Pradesh Andhra Pradesh (, abbr. AP) is a state in the south-eastern coastal region of India. It is the seventh-largest state by area covering an area of and tenth-most populous state with 49,386,799 inhabitants. It is bordered by Telangana to the ...
,
Maharashtra Maharashtra (; , abbr. MH or Maha) is a state in the western peninsular region of India occupying a substantial portion of the Deccan Plateau. Maharashtra is the second-most populous state in India and the second-most populous country subdi ...
, and
Telangana Telangana (; , ) is a state in India situated on the south-central stretch of the Indian peninsula on the high Deccan Plateau. It is the eleventh-largest state and the twelfth-most populated state in India with a geographical area of and 35 ...
also do not have speed limits by default.


Roads formerly without speed limits

Many roads without a maximum limit became permanently limited following the
1973 oil crisis The 1973 oil crisis or first oil crisis began in October 1973 when the members of the Organization of Arab Petroleum Exporting Countries (OAPEC), led by Saudi Arabia, proclaimed an oil embargo. The embargo was targeted at nations that had su ...
. For example,
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
and
Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
had no maximum restriction prior to 1973 on motorways and rural roads, but imposed a temporary maximum limit in response to higher fuel prices; the limit on motorways was increased to later in 1974.
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...
and
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
were the last remaining U.S. states relying exclusively on the basic rule, without a specific, numeric rural speed limit before the National Maximum Speed Law of 1974. After the repeal of federal speed mandates in 1996, Montana was the only state to revert to the basic rule for daylight rural speed regulation. The
Montana Supreme Court The Montana Supreme Court is the highest court of the state court system in the U.S. state of Montana. It is established and its powers defined by Article VII of the 1972 Montana Constitution. It is primarily an appellate court which reviews ...
ruled that the basic rule was too vague to allow citation, prosecution, and conviction of a driver; concluding enforcement was a violation of the
due process Due process of law is application by state of all legal rules and principles pertaining to the case so all legal rights that are owed to the person are respected. Due process balances the power of law of the land and protects the individual per ...
requirement of the
Montana Constitution The Constitution of the State of Montana is the primary legal document providing for the self-governance of the U.S. State of Montana. It establishes and defines the powers of the three branches of the government of Montana, and the rights o ...
. In response, Montana's legislature imposed a limit on rural freeways in 1999. Australia's
Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...
had no rural speed limit until 2007, and again from 2014 to 2016. Sections of the Stuart Highway had no limits as part of an open speed limit trial.


Method

Several methods exist to set up a speed limit: * Engineering * Harm minimization * Economic optimization * Expert system For instance, the ''Injury Minimization'' (known as Safe System) method takes into account the crash types that are likely to occur, the impact forces that result, and the tolerance of the human body to withstand these forces to set speed limit. This method is used in countries such as the Netherlands and Sweden. The ''Operating speed'' method sets the maximum speed at or around the 85th percentile speed. This reduces the need to enforce the speed limit, but also allows drivers to fail to select the appropriate travel speed, when they misjudge the risk their environment induces. This is one method used in the United States of America.


Enforcement

Speed limit enforcement is the action taken by appropriately empowered authorities to check that road vehicles are complying with the speed limit. Methods used include roadside speed monitoring, set up and operated by the police, and automated roadside speed camera systems, which may incorporate the use of an
automatic number plate recognition Automatic number-plate recognition (ANPR; see also other names below) is a technology that uses optical character recognition on images to read vehicle registration plates to create vehicle location data. It can use existing closed-circuit tel ...
system. In 2012, in the UK, 30% of drivers did not comply with speed limits. In Europe, between 2009 and 2012, 20% of European drivers have been fined for excessive speed. In 2012, in Europe, 62% of people supported the idea of setting up speed-limiting devices, with adequate tolerance levels in order to limit driver confusion. One efficient scheme consists of penalty points and charges for speeding slightly over the speed limit. Another possibility is to alter the roadway by implementing traffic calming measures, vehicle activated signs, or safety cameras. The city of Munich has adopted ''self-explaining roads'': roadway widths, intersection controls, and crossing types have been harmonized so that drivers assume the speed limit without a posted sign.


Effectiveness


Compliance

Speed limits are more likely to be complied with if drivers have an expectation that the speed limits will be consistently enforced. To be effective and abided by, the speed limits need to be perceived as credible; they should be reasonable regarding factors such as how well the driver can see ahead and to the sides on a particular road. Speed limits also need to conform to road infrastructure, education, and enforcement activity. In the UK, in 2017 the average free flow speed for each vehicle type is correlated with the applicable speed limit for that road type and for motorways and national speed limit single carriageway roads, the average free flow speed is below the designated speed limit for each vehicle type, except motorcycles on motorways.


Relationship with crash frequency

A 1998 US
Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program ...
report cited a number of studies regarding the effects of reductions in speed limits and the observed changes in speeding, fatalities, injuries and property damage which followed.Table 3, J. Stuster and Z. Coffman, Synthesis of Safety Research Related to Speed and Speed Management, FHWA-RD-98-154, July 1998 Some states increase penalties for more serious offenses, by designating as reckless driving, speeds greatly exceeding the maximum limit. A 2018 OECD-ITF case study established a strong relationship between speed and crash frequency: when the mean speed decreases, the number of crashes and casualties decreases; to the contrary, when speed increases, the number of crashes and casualties increases. In no case was an increase in mean speed associated with a decrease in the number of crashes or casualties.
South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large po ...
increased its maximum speed limit from 65 to 75 mph (120 km/h) in 1996. Annual surveys of speed on
South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large po ...
Interstate roads show that from 2000 to 2011, the average speed rose from 71 to 74 mph. A 1999 study found that the U.S. states that increased speed limits in the wake of the repeal of federally mandated speed limits had a 15% increase in fatalities. The ''Synthesis of Safety Research Related to Speed and Speed Limits'' report sponsored by the Federal Highway Administration, published in 1998, found that changing speed limits on low and moderate speed roads appeared to have no significant effect on traffic speed or the number of crashes, whilst on high-speed roads such as freeways, increased speed limits generally resulted in higher traffic speeds and more crashes. The report stated that limited evidence suggests that speed limits have a positive effect on a system wide basis. 'In general, changing speed limits on low and moderate speed roads appears to have little or no effect on speed and thus little or no effect on crashes, thereby suggesting that drivers travel at speeds they feel are reasonable and safe for the road and traffic regardless of the posted limit. However, on freeways and other high-speed roads, the speed limit increases generally lead to higher speeds and crashes. The change in speed is roughly one-fourth the change in speed limit. Results from international studies suggest that for every 1 mi/h change in speed, injury accidents will change by 5 percent (3 percent for every 1 km/h). However limited evidence suggests the net effect of speed limits may be positive on a system wide basis.' Research in 1998 showed that the reduction of some United Kingdom speed limits to had achieved only a 1 mph drop in speeds and no discernible reduction in accidents; 20 mph speed limit zones, which use self-enforcing
traffic calming Traffic calming uses physical design and other measures to improve safety for motorists, pedestrians and cyclists. It has become a tool to combat speeding and other unsafe behaviours of drivers in the neighbourhoods. It aims to encourage safe ...
, achieved average speed reductions of 10 mph; child pedestrian accidents were reduced by 70% and child cyclist accidents by 48%. Zones where speeds are set at 30 km/h (or 20 mph) are gaining popularity as they are found to be effective at reducing crashes and increasing community cohesion. Studies undertaken in conjunction with Australia's move from speed limits to in built-up areas found that the measure was effective in reducing speed and the frequency and severity of crashes. A study of the impact of the replacement of with speed limits in
New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...
, Australia, showed only a 0.5 km/h drop in urban areas and a 0.7 km/h drop in rural areas. The report noted that widespread community compliance would require a combination of strategies including traffic calming treatments. Information campaigns are also used by authorities to bolster support for speed limits, for example the Speeding. No one thinks big of you. campaign in Australia in 2007.


Justification

Speed limits are set primarily to balance
road traffic safety Road traffic safety refers to the methods and measures used to prevent road users from being killed or seriously injured. Typical road users include pedestrians, cyclists, motorists, vehicle passengers, horse riders, and passengers of on-road ...
concerns with the effect on travel time and mobility. Speed limits are also sometimes used to reduce consumption of fuel or in response to environmental concerns (e.g. to reduce vehicle emissions or fuel use). Some speed limits have also been initiated to reduce gas-oil imports during the
1973 oil crisis The 1973 oil crisis or first oil crisis began in October 1973 when the members of the Organization of Arab Petroleum Exporting Countries (OAPEC), led by Saudi Arabia, proclaimed an oil embargo. The embargo was targeted at nations that had su ...
.


Road traffic safety

According to a 2004 report from the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
, 22% of all injury mortality worldwide was from road traffic injuries in 2002, p. 34 fig 2.1 and without "increased efforts and new initiatives" casualty rates would increase by 65% between 2000 and 2020. p. 3 The report identified that the speed of vehicles was "at the core of the problem", p. 76 and recommended that speed limits be set appropriately for the road function and design, along with the implementation of physical measures related to the road and the vehicle, and increased effective enforcement by the police. p. 127 Road incidents are said to be the leading cause of deaths among children 10–19 years of age (260,000 children die a year; 10 million are injured). Maximum speed limits place an upper limit on speed choice and, if obeyed, can reduce the differences in vehicle speeds by drivers using the same road at the same time. Traffic engineers observe that the likelihood of a crash happening is significantly higher if vehicles are traveling at speeds faster or slower than the mean speed of traffic;, p. v 'The likelihood of a crash occurring is significantly greater for motorists traveling at speed slower and faster than the mean speed of traffic' when severity is taken into account, the risk is lowest for those traveling at or below the
median In statistics and probability theory, the median is the value separating the higher half from the lower half of a data sample, a population, or a probability distribution. For a data set, it may be thought of as "the middle" value. The basic f ...
speed and "increases exponentially for motorists travelling much faster". 'When the consequences of crashes are taken into account, the risk of being involved in an injury crash is lowest for vehicles that travel near the median speed or slower and increases exponentially for motorists traveling much faster' It is desirable to attempt to reduce the speed of road vehicles in some circumstances because the
kinetic energy In physics, the kinetic energy of an object is the energy that it possesses due to its motion. It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acce ...
involved in a motor vehicle collision is proportional to the square of the speed at
impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Imp ...
. The probability of a fatality is, for typical collision speeds, empirically correlated to the fourth power of the speed ''difference'' (depending on the type of collision, not necessarily the same as ''travel'' speed) at impact, rising much faster than kinetic energy. ;Kinetic energy: E_\mathrm = \frac m v^2 ;Braking distance during danger s_\mathrm \approx \frac \cdot \left( \frac \right) Typically
motorways A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms ...
have higher speed limits than conventional roads because motorways have features which decrease the likelihood of collisions and the severity of impacts. For example, motorways separate opposing traffic and crossing traffic, employ traffic barriers, and prohibit the most vulnerable users such as pedestrians and bicyclists. Germany's crash experience illustrates the relative effectiveness of these strategies on crash severity: on autobahns 22 people died per 1,000 injury crashes, a lower rate than the 29 deaths per 1,000 injury accidents on conventional rural roads. However, the rural risk is five times higher than on urban roads; speeds are higher on rural roads and autobahns than urban roads, increasing the severity potential of a crash. The net effect of speed, crash probability, and impact mitigation strategies may be measured by the rate of deaths per billion-travel-kilometres: the autobahn fatality rate is 2 deaths per billion-travel-kilometres, lower than either the 8.7 rates on rural roads or the 5.3 rate in urban areas. The overall national fatality rate was 5.6, slightly higher than urban rate and more than twice that of autobahns. The 2009 technical report ''An Analysis of Speeding-Related Crashes:Definitions and the Effects of Road Environments'' by the
National Highway Traffic Safety Administration The National Highway Traffic Safety Administration (NHTSA ) is an agency of the U.S. federal government, part of the Department of Transportation. It describes its mission as "Save lives, prevent injuries, reduce vehicle-related crashes" relat ...
showed that about 55% of all speeding-related crashes when fatal listed "exceeding posted speed limits" among their crash factors, and 45% had "driving too fast for conditions" among their crash factors. However, the authors of the report did not attempt to determine whether the factors were a crash cause, contributor, or an unrelated factor. Furthermore, separate research finds that only 1.6% of crashes are ''caused'' by drivers that exceed the posted speed limit. Finally, exceeding the posted limit may not be a remarkable factor in the crash analysis as there are roadways where virtually all motorists are in technical violation of the law. The speed limit will also take note of the speed at which the road was designed to be driven (the design speed), which is defined in the US as "a selected speed used to determine the various geometric design features of the roadway". However, traffic engineers recognize that "operating speeds and even posted speed limits can be higher than design speeds without necessarily compromising safety" since design speed is "based on conservative assumptions about driver, vehicle and roadway characteristics". Vision Zero, which envision reducing road fatalities and serious injuries to zero by 2020, suggests the following "possible long term maximum travel speeds related to the infrastructure, given best practice in vehicle design and 100% restraint use": "Roads with no possibility of a side impact or frontal impact" are sometimes designated as Type 1 (
motorways A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms ...
/
freeways A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms i ...
/
Autobahns The (; German plural ) is the federal controlled-access highway system in Germany. The official German term is (abbreviated ''BAB''), which translates as 'federal motorway'. The literal meaning of the word is 'Federal Auto(mobile) Track' ...
), Type 2 (" 2+2 roads"), or Type 3 ("
2+1 road 2+1 road is a specific category of three-lane road, consisting of two lanes in one direction and one lane in the other, alternating every few kilometres, and usually separated with a steel cable barrier. The second lane allows faster-moving ...
s"). These roadways have crash barriers separating opposing traffic, limited access,
grade separation In civil engineering (more specifically highway engineering), grade separation is a method of aligning a junction of two or more surface transport axes at different heights (grades) so that they will not disrupt the traffic flow on other tr ...
and prohibitions on slower and more vulnerable road users. Undivided rural roads can be quite dangerous even with speed limits that appear low by comparison. For example, in 2011, Germany's -limited rural roads had a fatality rate of 8.7 deaths per billion travel-km, over four times higher than the autobahn rate of 2 deaths. Autobahns accounted for 31% of German road travel in 2011, but just 11% (453 of 4,009) of traffic deaths. In 2018, an IRTAD WG published a document which recommended maximum speed limits, taking into account forces the human body can tolerate and survive.


Fuel efficiency

Fuel efficiency sometimes affects speed limit selection. The United States instituted a National Maximum Speed Law of , as part of the
Emergency Highway Energy Conservation Act The National Maximum Speed Limit (NMSL) was a provision of the federal government of the United States 1974 Emergency Highway Energy Conservation Act that effectively prohibited speed limits higher than . It was drafted in response to oil price ...
, in response to the
1973 oil crisis The 1973 oil crisis or first oil crisis began in October 1973 when the members of the Organization of Arab Petroleum Exporting Countries (OAPEC), led by Saudi Arabia, proclaimed an oil embargo. The embargo was targeted at nations that had su ...
to reduce fuel consumption. According to a report published in 1986 by
The Heritage Foundation The Heritage Foundation (abbreviated to Heritage) is an American conservative think tank based in Washington, D.C. that is primarily geared toward public policy. The foundation took a leading role in the conservative movement during the presi ...
, a
Conservative Conservatism is a cultural, social, and political philosophy that seeks to promote and to preserve traditional institutions, practices, and values. The central tenets of conservatism may vary in relation to the culture and civilization in ...
advocacy group, the law was widely disregarded by motorists and hardly reduced consumption at all. In 2009, the
American Trucking Associations The American Trucking Associations (ATA), founded in 1933, is the largest national trade association for the trucking industry. ATA represents more than 37,000 members covering every type of motor carrier in the United States through a federation ...
called for a 65 mph speed limit, and also national fuel economy standards, claiming that the lower speed limit was not effective at saving fuel.


Environmental considerations

Speed limits can also be used to improve local air quality issues or other factors affecting
environmental quality "Environmental Quality" is a set of properties and characteristics of the environment, either generalized or local, as they impinge on human beings and other organisms. It is a measure of the condition of an environment relative to the requirements ...
(e.g. the " environmental speed limits" in an area of
Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
). The
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
is also increasingly using speed limits as in response to environmental concerns. European studies have stated that, whereas the effects of specific speed reduction schemes on particulate emissions from trucks are ambiguous, lower maximums speed for trucks consistently result in lower emissions of CO2 and better
fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device ...
.


Advocacy

Speed limits, and especially some of the methods used to attempt to enforce them, have always been controversial. A variety of organisations and individuals either oppose or support the use of speed limits and their enforcement.


Opposition

Speed limits and their enforcement have been opposed by various groups and for various reasons since their inception. In the UK, the Motorists' Mutual Association (est. 1905) was formed initially to warn members about speed traps; the organisation would go on to become the AA. More recently, advocacy groups seek to have certain speed limits as well as other measures removed. For example, automated
camera A camera is an optical instrument that can capture an image. Most cameras can capture 2D images, with some more advanced models being able to capture 3D images. At a basic level, most cameras consist of sealed boxes (the camera body), with ...
enforcement has been criticised by motoring advocacy groups including the Association of British Drivers, and the German Auto Club (ADAC)., Press Release, June 2010. Arguments used by those advocating a relaxation of speed limits or their removal include: * A 1994 peer-reviewed paper by Charles A. Lave et al. titled ''Did the 65 mph Speed Limit Save Lives?'' which states as evidence that a higher speed limit may create a positive shift in traffic to designated safer roads. * A 1998 report in the ''
Wall Street Journal ''The Wall Street Journal'' is an American business-focused, international daily newspaper based in New York City, with international editions also available in Chinese and Japanese. The ''Journal'', along with its Asian editions, is published ...
'' titled "Highways are safe at any speed", stating when speed limits are set artificially low, tailgating, weaving and speed variance (the problem of some cars traveling significantly faster than others) make roads less safe. *A 2007 ePetition to the UK government calling for speed cameras to be scrapped on the basis that the benefits were exaggerated and that they may actually increase casualty levels, conducted by Safe Speed, a UK advocacy organisation campaigning for higher speed limits, which received over 25,000 signatures. * A 2008 declaration by the German Automobile Manufacturer's Association calling general limits "patronizing," arguing instead for variable speed limits. The Association also stated that "raising the speed limits in Denmark (in 2004 from 110 km/h to 130 km/h) and Italy (2003 increase on six-lane highways from 130 km/h to 150 km/h) had no negative impact on traffic safety. The number of accidental deaths even declined". *In a 2010 ADAC report, it was said that an autobahn speed limit was unnecessary because numerous countries with a general highway speed limit had worse safety records than Germany. However, more recent data show that Germany ranks in the lower middle field in a Europe-wide comparison regarding the number of fatalities per billion vehicle kilometers traveled on motorways. ETSC considers that those data are not comparable, because estimations of the number of kilometers traveled are not estimated the same way in different countries. Since 2020, the ADAC is „nicht mehr grundsätzlich“ ("no longer in principle") against a speed limit on autobahns.


Support

Various other advocacy groups press for stricter limits and better enforcement. The
Pedestrians Association Living Streets is the United Kingdom charity for everyday walking. It was founded in 1929 as the Pedestrians' Association and became known as the Pedestrians' Association for Road Safety in 1952. The current name was adopted in 2001. It is a v ...
was formed in the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
in 1929 to protect the interests of the pedestrian. Their president published a critique of motoring legislation and the influence of motoring groups in 1947 titled "Murder most foul", which laid out in an emotional but detailed view of the situation as they saw it, calling for tighter speed limits. Historically, the Pedestrians' Association and the Automobile Association were described as "bitterly opposed" in the early years of United Kingdom motoring legislation. More recently organisations such as
RoadPeace RoadPeace is the national charity for road crash victims in the UK. It supports the people affected by road crashes with emotional and practical support and advocacy. It operates a help line and provides practical support to people affected. R ...
,
Twenty is Plenty 30 km/h zones (30 kilometres per hour zones) and the similar 20 mph zones (20 miles per hour zones) are forms of speed management used across areas of urban roads in some jurisdictions. The nominal maximum speed limits in these zones a ...
, and Vision Zero have campaigned for lower speed limits in residential areas. In the United States, advocacy groups favoring stricter limits and better enforcement include the Advocates for Highway and Auto Safety, Insurance Institute for Highway Safety and the
National Safety Council The National Safety Council (NSC) is a 501(c)(3) nonprofit, public service organization promoting health and safety in the United States. Headquartered in Itasca, Illinois, NSC is a member organization, founded in 1913 and granted a congressi ...
.


Signage

Most countries worldwide measure speed limits in
kilometres per hour The kilometre per hour ( SI symbol: km/h; non-standard abbreviations: kph, km/hr) is a unit of speed, expressing the number of kilometres travelled in one hour. History Although the metre was formally defined in 1799, the term "kilometres per h ...
, while the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
, and several smaller countries measure speed limits in
miles per hour Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller cou ...
instead. Signs in
Samoa Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); ...
display both units simultaneously. There are two basic designs for speed limit signs: the
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 designed to increase road safety and aid international road traffic by standardising the signing system for ro ...
specifies a white or yellow circle with a red border, while the '' Manual on Uniform Traffic Control Devices'' (MUTCD) published by the United States
Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program ...
specifies a white rectangle with the legend ''SPEED LIMIT''. Vienna-style speed limit signs originated in Europe and are used in most of the world, including many countries that otherwise follow the MUTCD. Variations on the MUTCD design are used in
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
,
Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
,
Liberia Liberia (), officially the Republic of Liberia, is a country on the West African coast. It is bordered by Sierra Leone to Liberia–Sierra Leone border, its northwest, Guinea to Guinea–Liberia border, its north, Ivory Coast to Ivory Coast� ...
,
Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and unincorporated ...
, the mainland United States, the U.S. Virgin Islands. Australia also used a variation on the MUTCD design until the country metricated in 1974. In the United States, Canada, Australia and Peru, speed limit signs are rectangular. In most of the United States, speed limit signs bear the words ''SPEED LIMIT'' above the numeric speed limit, as specified in the MUTCD. However, in
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
and
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
, speed limits are often labeled ''MAXIMUM SPEED'' instead. In Oregon, most speed limit signs are simply labeled ''SPEED''. Canada has similar signs bearing the legend ''MAXIMUM'', which has a similar meaning in
English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ...
and
French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...
, the country's two main languages. Peru uses a similar, reversed variation of the MUTCD order in which the words ''VELOCIDAD MAXIMA'' (speed limit) are placed below the numeric limit.
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
uses the same rectangular design, but inscribes the numeric speed limit within a red circle as in Vienna Convention signs. The MUTCD formerly specified an optional metric design that included the words ''SPEED LIMIT'' and the numeric limit inscribed within a black circle, though it was rarely used in the United States; this design is still occasionally found in Liberia. Speed limit signs of
Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...
and
Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Co ...
are square, unlike the United States. In the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
, large signposts showing the national (maximum) speed limits of the respective country are usually erected immediately after
border crossing Border control refers to measures taken by governments to monitor and regulate the movement of people, animals, and goods across land, air, and maritime borders. While border control is typically associated with international borders, it a ...
s, with a repeater sign some after the first. Some places provide an additional "speed zone ahead" ahead of the restriction, and speed limit reminder signs may appear at regular intervals, which may be painted on the road surface. In
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
, the type, location, and frequency of speed limit signs are covered by regulation 615 of the Ontario Highway Traffic Act.


Maximum speed limit

File:Hungary road sign C-033-50.svg, Speed limit sign for 50 km/h ( Vienna Convention Sign C14, most of the world follows this pattern) File:UK traffic sign 670V50.svg, UK sign for 50  mph File:Australia road sign R4-1 (50).svg, Standard speed limit sign used in
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
showing 50 km/h (all speed limit signs are rectangular) File:Sweden road sign C31-5.svg, Alternative Vienna Convention sign with an amber background used in few countries, such as Sweden, Finland and Iceland File:IE road sign RUS-043.svg,
Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...
includes the text "km/h" since going metric in 2005 File:Indonesia New Road Sign Pro 4h.png, Indonesia (in km/h) includes the text "km" on the top right corner; this model was also used by a number of European countries such as Germany, Italy an
Switzerland
until the 1960s. File:Japan road sign 323 (50).svg,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
uses blue numerals; km/h File:Samoa - Speed Limit.svg,
Samoa Samoa, officially the Independent State of Samoa; sm, Sāmoa, and until 1997 known as Western Samoa, is a Polynesian island country consisting of two main islands ( Savai'i and Upolu); two smaller, inhabited islands ( Manono and Apolima); ...
uses both
miles per hour Miles per hour (mph, m.p.h., MPH, or mi/h) is a British imperial and United States customary unit of speed expressing the number of miles travelled in one hour. It is used in the United Kingdom, the United States, and a number of smaller cou ...
and
kilometres per hour The kilometre per hour ( SI symbol: km/h; non-standard abbreviations: kph, km/hr) is a unit of speed, expressing the number of kilometres travelled in one hour. History Although the metre was formally defined in 1799, the term "kilometres per h ...
File:UAE Speed Limit - 60 kmh.svg, The
United Arab Emirates The United Arab Emirates (UAE; ar, اَلْإِمَارَات الْعَرَبِيَة الْمُتَحِدَة ), or simply the Emirates ( ar, الِْإمَارَات ), is a country in Western Asia (Middle East, The Middle East). It is ...
and
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the Ara ...
(km/h) use both Western Arabic and Eastern Arabic numerals File:CA-ON road sign Rb-001-060.svg,
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
(displayed in km/h; All speed limit signs are MUTCD style) File:Ontario Rb-1A.svg, Canada (
Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...
) File:British Columbia R-004-50.svg, Canada (
Yukon Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...
and
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
) File:MUTCD R2-1.svg,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
(in mph) File:Oregon-speed.svg, United States (
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
variant) File:NYSDOT NYR2-2.svg, United States (
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
variant; "CITY", "VILLAGE", "TOWN", or a variant of the word "AREA" can be used in place of "STATE")
File:MUTCD R2-1 METRIC.svg, United States (metric) File:Peru road sign R-30.svg, Peru (metric, all speed limit signs are rectangular, and the reversed MUTCD order is used there)
Some speed limits are applicable to a zone. File:Zeichen 274.1 - Beginn einer Tempo 30-Zone, StVO 2013.svg, Zone 30 entry in Germany with 30 km/h speed limit. File:Zeichen 274.2 - Ende einer Tempo 30-Zone (einseitig), StVO 2013.svg, Zone 30 end in Germany File:Signal B30.svg, Zone 30 entry in France with 30 km/h speed limit. File:France road sign B51 (30).svg, Zone 30 end in France


Minimum speed limit

Minimum speed limits are often expressed with signs using blue circles, based on the obligatory sign specifications of the Vienna Convention on Road Signs and Signals. In the United States, minimum speed limit signs are identical to their respective maximum speed limit signs, with ''SPEED LIMIT'' replaced with ''MINIMUM SPEED''. Some South American countries (e.g.: Argentina) use a red border. Japan and South Korea use their normal speed limit sign, with a line below the limit. File:Zeichen 275 - Vorgeschriebene Mindestgeschwindigkeit, StVO 1992.svg, Common minimum speed limit sign File:UAE Minimum Speed Limit - 60 kmh.svg, The
United Arab Emirates The United Arab Emirates (UAE; ar, اَلْإِمَارَات الْعَرَبِيَة الْمُتَحِدَة ), or simply the Emirates ( ar, الِْإمَارَات ), is a country in Western Asia (Middle East, The Middle East). It is ...
and
Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the Ara ...
(km/h) use both Western Arabic and Eastern Arabic numerals File:Argentina road sign R16.svg,
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...
, km/h File:Québec P-070-1-60.svg,
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
, km/h (rare outside the province of
Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirte ...
) File:Chile road sign RR-2 (40).svg,
Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...
; km/h File:Colombia road sign SR-30A.svg,
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the ...
; km/h Indonesia New Road Sign Mndtry 44.png,
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...
(includes the text "km" on the top right corner); km/h File:Japan road sign 324 (30).svg,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
; km/h File:Philippines road sign R4-3 (40).svg,
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
; km/h File:South Korea road sign 225.svg,
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
(which looks similar to this sign from
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
except the numerals are black); km/h File:UK traffic sign 672v40.svg, UK minimum speed limit sign, in mph File:MUTCD R2-4.svg,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
; mph File:MUTCD R2-4a.svg, United States (dual maximum and minimum speeds) File:MUTCD R2-4 METRIC.svg, United States (metric) File:MUTCD R2-4a METRIC.svg, United States (metric, dual maximum and minimum speeds)


Special speed limits

In some countries, speed limits may apply to certain classes of vehicles or special conditions such as night-time. Usually, these speed limits will be reduced from the normal limit for safety reasons. File:Au.speedlimit.40 at times.svg,
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
- Speed limit during certain times File:AU-QLD road sign R4-Q05.svg, Australia - Road Train speed limit File:New Zealand RG-3.svg, New Zealand - Limited Speed Zone (Maximum speed limit is 100 km/h, reduces to 50 km/h if dangerous conditions exist such as bad weather) File:RomanianTrafficSign C30-SpeedLimitPerVehicleCategory-130-100 2011.svg,
Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...
- Car and truck speed limit File:MUTCD Sign Assembly - R2-1 with G20-5aP.svg,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
- Roadworks zone speed limit File:MUTCD R2-2.svg, United States - Trucks speed limit File:Virginia R2-VP1.svg, United States - Towed vehicles speed limit File:MUTCD R2-3.svg, United States - Night time speed limit File:MUTCD EM-4.svg, Unique speed limit sign in the United States on evacuation routes requiring drivers to maintain the maximum safe speed File:Korean Traffic sign (Safe Speed 30kph).svg, Safe speed sign in
South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...


Speed limit derestriction

In some countries, derestriction signs are used to mark where a speed zone ends. The speed limit beyond the sign is the prevailing limit for the general area; for example, the sign might be used to show the end of an urban area. In the United Kingdom, the sign means that the national speed limit applies (60 mph on open roads and 70 mph on dual carriageways and motorways). In New Zealand it means you are on an open road, but the maximum legal speed of 100 km/h still applies. On roads without general speed limits, such as the German
Autobahn The (; German plural ) is the federal controlled-access highway system in Germany. The official German term is (abbreviated ''BAB''), which translates as 'federal motorway'. The literal meaning of the word is 'Federal Auto(mobile) Track' ...
, a portion of the
Stuart Highway Stuart Highway is a major Australian highway. It runs from Darwin, in the Northern Territory, via Tennant Creek and Alice Springs, to Port Augusta in South Australia; a distance of . Its northern and southern extremities are segments of Aus ...
, and rural areas on the Isle of Man, it means the end of all quantitative speed limits. File:Spain traffic signal r501.svg, Common ''maximum speed limit'' derestriction sign File:Italian traffic signs - fine limite minimo di velocità 30.svg, Common ''minimum speed limit'' derestriction sign File:Italian traffic signs - fine velocità consigliata 60.svg, Common ''advisory speed limit'' derestriction sign File:Australia road sign R4-2.svg,
Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...
, now relatively rare File:Australia road signs R4-12 (60).svg, Australia File:New Zealand road sign R1-3.svg,
Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to ...
,
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
,
Ireland Ireland ( ; ga, Éire ; Ulster-Scots: ) is an island in the North Atlantic Ocean, in north-western Europe. It is separated from Great Britain to its east by the North Channel, the Irish Sea, and St George's Channel. Ireland is the s ...
pre-2005,
New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
,
Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...
,
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federal constitutional monarchy consists of thirteen states and three federal territories, separated by the South China Sea into two regions: Peninsular Malaysia and Borneo's East Mal ...
and
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...
File:Zeichen 282 - Ende sämtlicher Streckenverbote, StVO 1970.svg,
Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwee ...
File:Japan road sign 323 (40) and 507-C.svg,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...
File:Japan road sign 323 (40) and 507-A.svg, Japan - Left arrow (Right arrow means "from here") File:Philippines road sign R4-2.svg,
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
File:Philippines road sign R4-2P (60).svg, Philippines File:NYSDOT NYR2-11.svg, End speed limit 35 mph
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
File:Virginia R2-V2.svg, End speed limit (custom) United States (archaic)


Advisory speed limit

Advisory speed limits may provide a safe suggested speed in an area, or warn of the maximum safe speed for dangerous curves. In Germany, an advisory speed limit may be combined with a traffic signal to recommend the speed at which drivers should drive to reach the next light at its green phase, thereby avoiding a stop.


Technology

Some European cars include in-vehicle systems that support drivers’ compliance with the speed limit, known as intelligent speed adaptation (ISA). ISA supports drivers in complying with the speed limit in various parts of the network, while speed limiters for heavy goods vehicles and coaches only govern the maximum speed. These systems have positive effects on speed behaviour, and improve safety. A speed-limiting device, such as ISA are considered useful by 25% of European car drivers. In 2019,
Google Maps Google Maps is a web mapping platform and consumer application offered by Google. It offers satellite imagery, aerial photography, street maps, 360° interactive panoramic views of streets (Street View), real-time traffic conditions, and rou ...
integrated alerts for speed traps within its application, along with audible alerts for nearby speed cameras. The technology was first developed by
Waze Waze (; he, ווייז, label=Hebrew), formerly FreeMap Israel, is a subsidiary company of Google that provides satellite navigation software on smartphones and other computers that support the Global Positioning System (GPS). In addition to ...
, with requests for it to be removed from the application by police officers.


See also

* Advisory speed limit * Assured clear distance ahead (ACDA) * Design speed * Functional classification * Negligence per se * Operating speed * Radar speed sign * Solomon curve *
Speed limits by country A speed limit is the limit of speed allowed by law for road vehicles, usually the maximum speed allowed. Occasionally, there is a minimum speed limit. Advisory speed limits also exist, which are recommended but not mandatory speeds. Speed limit ...
* Stopping sight distance * Traffic violations reciprocity *
Traffic psychology Traffic psychology is a discipline of psychology that studies the relationship between psychological processes and the behavior of road users. In general, traffic psychology aims to apply theoretical aspects of psychology in order to improve traff ...


Notes


Documents referenced from 'Notes' section

* * * *


References


Further reading


Actual Speeds on the Roads Compared to the Posted Limits
Final Report 551, Arizona Dept of Transportation, October 2004.
Effects of Raising and Lowering Speed Limits on Selected Roadway Sections
, United States Publication No. FHWA-RD-97-084, January 1997.
Effect of 20 mph traffic speed zones on road injuries in London, 1986-2006: controlled interrupted time series analysis
British Medical Journal ''The BMJ'' is a weekly peer-reviewed medical trade journal, published by the trade union the British Medical Association (BMA). ''The BMJ'' has editorial freedom from the BMA. It is one of the world's oldest general medical journals. Origi ...
2009.
Engineering Speed Limits - FHWA Safety Program
United States Department of Transportation - Federal Highway Administration, Office of Safety, 1200 New Jersey Avenue, SE, Washington DC 20590. * "Reducing Speeding-Related Crashes Involving Passenger Vehicles." National Transportation Safety Board, 490 L'Enfant Plaza, SW, Washington, D.C. 20594, July 2017. Retrieved fro


Special Report 254: Managing Speed
Transportation Research Board, 1998.
The Speeding Driver: Who, How and Why?
A research report by the Scottish government into the psychology of the speeding driver.

The comprehensive UK report into the effects of speeding. * * *


Law Review

* *


External links


A Walk Through The History of Speed Limit Signs in The US



Global map of speed limits from OpenStreetMap
{{DEFAULTSORT:Speed Limit Road speed limit, * Law enforcement Road safety Road traffic management Traffic law