Editing Speed limit (section)

==Regulations==
{{Main|Speed limits by country}}
[[File:World Speed Limits.svg|thumb|upright=1.5|Highest-posted speed limits around the world. Kilometres per hour are on the left and miles per hour on the right.*]]

[[File:World Map of Speed Limit Units on Traffic Signs.svg|thumb|upright=1.5|Speed limit units on [[traffic sign]]s around the world:
{{legend|#005ce6|Kilometres per hour (km/h)}}
{{legend|#ff8000|Miles per hour (mph)}}
{{legend|#22b14c|Both}}
{{legend|#c0c0c0|none known}}
]]

Most countries use the [[Metric system|metric]] speed unit of [[kilometres per hour]], while others, including the [[United States]], [[United Kingdom]], and [[Liberia]], use speed limits given in [[miles per hour]].

=== Vienna Convention on Road Traffic ===

In countries bound by the [[Vienna Convention on Road Traffic|Vienna Conventions on Road Traffic]] (1968 & 1977), Article 13 defines a basic rule for speed and distance between vehicles:<ref>[[Vienna Convention on Road Traffic]]</ref>

{{Blockquote|Every driver of a vehicle shall in all circumstances have his vehicle under control to be able to exercise due and proper care and to be at all times in a position to perform all manœuvres required of him. He shall, when adjusting the speed of his vehicle, pay constant regard to the circumstances, in particular the lie of the land, the state of the road, the condition and load of his vehicle, the weather conditions and the density of traffic, so as to be able to stop his vehicle within his range of forward vision and short of any foreseeable obstruction. He shall slow down and if necessary stop whenever circumstances so require, and particularly when visibility is not excellent.}}

=== 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]], this is known as the '''[[reasonable man]]''' requirement.<ref>{{cite web|url=http://www.opsi.gov.uk/acts/acts1991/ukpga_19910040_en_2#pt1-pb4-l1g6|title=Road Traffic Act 1991|quote=A person is guilty of an offence if he intentionally and without lawful authority or reasonable cause— (a) causes anything to be on or over a road, or (b) interferes with a motor vehicle, trailer or cycle, or (c) interferes (directly or indirectly) with traffic equipment, in such circumstances that it would be obvious to a reasonable person that to do so would be dangerous. (2) In subsection (1) above "dangerous" refers to danger either of injury to any person while on or near a road, or of serious damage to property on or near a road; and in determining for the purposes of that subsection what would be obvious to a reasonable person in a particular case, regard shall be had not only to the circumstances of which he could be expected to be aware but also to any circumstances shown to have been within the knowledge of the accused.|access-date=2010-05-03|publisher=Office of Public Sector Information}}</ref>

The German Highway Code (''Straßenverkehrs-Ordnung'') section on speed begins with the statement (translated to English):<ref>{{cite web|url=http://www.gesetze-im-internet.de/stvo_2013/__3.html|title=§ 3 StVO 2013 - Einzelnorm|website=www.gesetze-im-internet.de}}</ref>
<blockquote>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.</blockquote>

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, etc.).<ref>{{cite web|url=https://www.legifrance.gouv.fr/codes/id/LEGIARTI000037411312/2018-09-19/|title=Section 2 : Maîtrise de la vitesse. (Articles R413-17 à R413-19) - Légifrance|website=www.legifrance.gouv.fr}}</ref> If drivers do not control 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,<ref>{{cite web|url=https://www.sciencedaily.com/releases/2009/04/090410123455.htm|title=On Gravel Roads, People Drive At Speed They Are Comfortable With, Regardless Of Posted Limit|access-date=2010-10-13|quote="We found that people are driving at speeds based on their perceptions and existing conditions – regardless of the speed limit," said Dissanayake, who also is a faculty member with [[Kansas State University|K-State]]'s University Transportation Center...when it came to speed limits, and the actual speeds are driven, the difference was not significant between {{cvt|35|mph}} and {{cvt|55|mph}} roads. An example is the gravel roadways in Johnson County and Miami County. The study found that though two-speed limits exist, the driving characteristics were the same. While Johnson County's speed limit is {{cvt|35|mph}} and posted, the average actual speed of {{cvt|37.5|mph}} was higher than the average actual speed of {{cvt|35.8|mph}} in Miami County, where the speed limit is {{cvt|55|mph}} and not posted.}}
</ref> or when drivers encounter sharp corners, a blinding glare,<ref>{{cite web|url=http://www.lexisnexis.com/clients/CACourts/|title=Hatzakorzian v. Rucker-Fuller Desk Co., 197 Cal. 82|date=1925-09-21|publisher=Official California Reports, Vol. 197, p. 82 (California Supreme Court reporter)|quote="Under the circumstances of the present case – the narrowness of the unpaved portion of the highway, the darkness of the night and the '''blinding''' of Kennell by the '''glare of the lights''' reflected from the headlights of the approaching machine – the highway over which Kennell was traveling was beset by danger of an extraordinary character from the time his vision became so obscured as to make it impossible for him to see plainly the road before him to the time that he struck the deceased. Thus the ordinary care with which Kennell was charged in driving his car over the highway required such an amount of such care as was commensurate with the exactions of the extraordinary dangerous circumstances under which he was then operating his car. The respective rights and duties of drivers of automobiles and other vehicles and of pedestrians have repeatedly been by the courts of this state clearly pointed out..."}}</ref> darkness, crossing traffic,<ref>{{cite report|date=1950-11-14|section=Allin v. Snavely|section-url=http://law.justia.com/cases/california/calapp2d/100/411.html|title=Official California Appellate Reports|series=2nd Series Vol. 100|page=411|access-date=2013-07-27|quote="A driver by insisting on his lawful right of way may violate the basic speed law as provided by Veh. Code, § 22350, and thus become guilty of negligence." (CA Reports Headnote #[2])}}</ref> 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).<ref>{{cite report|section=Riggs v. Gasser Motors|section-url=http://law.justia.com/cases/california/calapp2d/22/636.html|date=1937-09-25|title=Official California Appellate Reports|series=2nd Series Vol. 22|page=636|access-date=2013-07-27|quote=It is common knowledge that intersecting streets in cities present a continuing hazard, the degree of hazard depending upon the extent of the use of the intersecting streets and the surrounding circumstances or conditions of each intersection. Under such circumstances, the basic [speed] law...is always governing.}} See [http://courts.ca.gov/opinions-slip.htm Official Reports Opinions Online]
</ref><ref>{{cite web|url=http://law.justia.com/cases/california/calapp2d/139/65.html|title=Leeper v. Nelson, 139 Cal. App. 2d 65|date=1956-02-06|publisher=Official California Appellate Reports (2nd Series Vol. 139, p. 65)|access-date=2013-07-27|quote=The operator of an automobile is bound to anticipate that he may meet persons or vehicles at any point of the street, and he must in order to avoid a charge of negligence, keep a proper lookout for them and keep his machine under such control as will enable him to avoid a collision with another automobile driven with care and caution as a reasonably prudent person would do under similar conditions.}} See [http://law.justia.com/cases/california/calapp2d/91/142.html Huetter v. Andrews, 91 Cal. App. 2d 142], [http://www.lexisnexis.com/clients/CACourts/ Berlin v. Violett, 129 Cal.App. 337], [http://www.lexisnexis.com/clients/CACourts/ Reaugh v. Cudahy Packing Co., 189 Cal. 335], and [http://courts.ca.gov/opinions-slip.htm Official Reports Opinions Online]
</ref>

In the United States, this requirement is referred to as the '''basic rule''',<ref name="www-nrd.nhtsa.dot.gov">{{cite web|url=http://www-nrd.nhtsa.dot.gov/Pubs/811090.PDF|title=An Analysis of Speeding-Related Crashes:Definitions and the Effects of Road Environments|date=February 2009|publisher=U.S. Department of Transportation, National Highway Traffic Safety Administration|access-date=2010-04-25|quote=Appendix: The basic rules governing the speed of vehicles in Kansas, Kentucky, Maryland, Montana, North Carolina, and Wisconsin.}}</ref> as outlined by US federal government law (49 CFR 392.14<ref>{{cite web|url=https://www.law.cornell.edu/cfr/text/49/392.14|title=49 CFR 392.14 - Hazardous conditions; extreme caution.|website=LII / Legal Information Institute}}</ref>), which applies in all states as permitted under the [[commerce clause]] and [[due process clause]].<ref name="Stanko">{{cite web|url=https://caselaw.findlaw.com/mt-supreme-court/1110919.html|title=''State v. Stanko''|publisher=Supreme Court of Montana|year=1998}}</ref><ref name="CDLM">{{cite book|title=Commercial Driver License Manual 2005|chapter=Section 2 – Driving Safely|url=https://www.fmcsa.dot.gov/registration/commercial-drivers-license/commercial-drivers-license-manual|chapter-url=https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/2005%20CDL%20Driver%20Manual%20-July%202014%20-%20FINAL.pdf|pages=2-15, 2-19, 2-26, 13-1|date=July 2014|publisher=United States Department of Transportation|quote=[pg 2-15] ''' ''2.6.4 – Speed and Distance Ahead:'' ''' '''You should always be able to stop within the distance you can see ahead.''' Fog, rain, or other conditions may require that you slow down to be able to stop in the distance you can see. ... [pg 2-19] ''' ''2.8.3 – Drivers Who Are Hazards: Vehicles may be partly hidden by blind intersections or alleys.'' ''' If you only can see the rear or front end of a vehicle but not the driver, then he or she can't see you. Be alert because he/she may back out or enter into your lane. '''Always be prepared to stop.''' ... [pg 2-26] ''' ''2.11.4 – Vehicle Factors: Headlights.'' ''' At night your headlights will usually be the main source of light for you to see by and for others to see you. You can't see nearly as much with your headlights as you see in the daytime. With low beams, you can see ahead about 250 feet and with high beams about 350-500 feet. '''You must adjust your speed to keep your stopping distance within your sight distance.''' This means going slowly enough to be able to stop within the range of your headlights. ... [pg 13-1]''' ''13.1.2 – Intersections'' ''' As you approach an intersection: Check traffic thoroughly in all directions. '''Decelerate gently. Brake smoothly''' and, if necessary, change gears. If necessary, come to a complete stop (no coasting) behind any stop signs, signals, sidewalks, or stop lines maintaining a safe gap behind any vehicle in front of you. Your vehicle must not roll forward or backward. When driving through an intersection: Check traffic thoroughly in all directions. '''Decelerate ''and'' yield to any pedestrians and traffic in the intersection.''' Do not change lanes while proceeding through the intersection. Keep your hands on the wheel.}}</ref> 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".<ref>{{cite web|url=http://www.dmv.ca.gov/pubs/vctop/d11/vc22350.htm|title=California Vehicle Code section 22350: Basic Speed Law|quote=No person shall drive a vehicle upon a highway at speed greater than is reasonable or prudent having due regard for weather, visibility, the traffic on, and the surface and width of, the highway, and in no event at a speed which endangers the safety of persons or property.|date=1963-09-20|access-date=2010-04-25|publisher=California Department of Motor Vehicles|archive-date=2010-05-05|archive-url=https://web.archive.org/web/20100505015126/http://www.dmv.ca.gov/pubs/vctop/d11/vc22350.htm|url-status=dead}}</ref> The reasonable speed may be different than the posted speed limit. ''Basic rule'' speed laws are statutory reinforcements of the centuries-old [[common law]] [[negligence]] doctrine as specifically applied to vehicular speed.<ref>{{cite web|url=http://www.lexisnexis.com/clients/CACourts/|title=Reaugh v. Cudahy Packing Co., 189 Cal. 335|date=1922-07-27|publisher=Official California Reports, Vol. 189, p. 335, (California Supreme Court reporter)|access-date=2013-07-27|quote=This is but a reiteration of the rule, in statutory form, which has always been in force without regard to a statutory promulgation to the effect that drivers or operators of vehicles, and more particularly motor vehicles, must be specially watchful in anticipation of the presence of others at places where other vehicles are constantly passing, and where men, women, and children are liable to be crossing, such as corners at the intersections of streets or other similar places or situations where people are likely to fail to observe an approaching automobile.}}</ref> Citations for violations of the basic speed law without a crash<ref>{{cite web|url=https://www.pe.com/2015/08/13/temecula-inquiries-prompt-new-speed-survey/|title=TEMECULA: Inquiries prompt new speed survey|date=2015-08-13}}</ref> have sometimes been ruled unfairly vague or arbitrary, hence a violation of the [[due process clause|due process of law]], at least in the State of Montana.<ref>{{cite web|url=https://caselaw.findlaw.com/mt-supreme-court/1110919.html|title=FindLaw's Supreme Court of Montana case and opinions|website=Findlaw}}</ref> Even within states, differing jurisdictions (counties and cities) choose to prosecute similar cases with differing approaches.<ref>{{cite web|url=http://vincenzeslaw.com/4-ways-virginia-reckless-driving-charges-handled-differently-fairfax-county-arlington-alexandria-stafford/|title=4 ways Virginia Reckless Driving charges are handled differently in Fairfax County, Arlington, Alexandria, and Stafford|last=Vincenzes|first=Brent|access-date=2015-04-21|archive-date=2015-04-24|archive-url=https://web.archive.org/web/20150424000543/http://vincenzeslaw.com/4-ways-virginia-reckless-driving-charges-handled-differently-fairfax-county-arlington-alexandria-stafford/|url-status=dead}}</ref>

=== Excessive speed ===
Consequential results of basic law violations are often categorized as ''excessive speed'' crashes; for example, the leading cause of [[German autobahns#Safety|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.<ref name="www.destatis.de 2012">{{cite web|title=Unfallentwicklung auf deutschen Straßen 2012 (Accident trends on German roads 2012)|date=2013-07-10|url=https://www.destatis.de/DE/Publikationen/Thematisch/TransportVerkehr/Verkehrsunfaelle/PK_Unfallentwicklung_PDF.pdf?__blob=publicationFile|publisher=Statistisches Bundesamt (Federal Statistics Office)|quote=(Seite 19) Mit 29 Getöteten je 1 000 Unfälle mit Personenschaden ist das Todesrisiko auf Landstraßen fünfmal höher als auf Innerortsstraßen und auch höher als auf Autobahnen, auf denen 22 Personen je 1000 Unfälle starben. Ein Grund für das wesentlich höhere Risiko auf Landstraßen und Autobahnen ist, dass hier wesentlich schneller gefahren wird als auf Innerortsstraßen und dadurch die Unfallschwere steigt... (Seite 20) Hauptunfallursache auf Autobahnen ist die "nicht angepasste Geschwindigkeit." Im Jahr 2012 waren mehr als ein Drittel aller Unfälle mit Personenschaden auf Autobahnen Unfälle, bei denen mindestens einem Beteiligten dieses Fehlverhalten zur Last gelegt wurde. Bei insgesamt 6 587 sogenannten Geschwindigkeitsunfällen kamen 179 Menschen zu Tode, das heißt nahezu die Hälfte (46,3 %) aller Getöteten auf Autobahnen... (Seite 20) Hierbei ist allerdings zu berücksichtigen, dass die Unfallursache "nicht angepasste Geschwindigkeit" häufig nicht bedeutet, dass die zulässige Höchstgeschwindigkeit überschritten worden ist. "Nicht angepasste Geschwindigkeit" wird von der Polizei bei einem Unfall auch dann als Ursache erfasst, wenn ein Beteiligter für die vorliegenden Straßen- oder Witterungsverhältnisse zu schnell gefahren ist.|access-date=2013-09-23|website=www.destatis.de|format=PDF}}</ref> 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.<ref name="www.destatis.de 2012" /><ref name="Starnberg Fatality 2013">{{cite web|url=http://www.merkur-online.de/lokales/starnberg/landkreis/autobahn-gesperrt-schwerer-unfall-starnberg-mm-3040140.html|title=A 95: Polizei geschockt über "immenses Tempo" [Translation: A 95: Police Shocked At High Speed]|date=2013-08-05|publisher=Merkur Online [The Mercury online version]|access-date=2013-09-29|quote=den stellvertretenden Kommandanten der Feuerwehr aus Hohenschäftlarn (Kreis München), Daniel Buck... war mit seinen Kollegen einer der ersten an der Unfallstelle, an der ein Porschefahrer (51) so schnell in den Toyota einer 67-jährigen Weilheimerin bretterte, dass sich ihr Auto mehrmals überschlug. Die Frau musste noch vor Ort reanimiert werden, starb jedoch später im Krankenhaus. Die beiden Männer im Porsche kamen mit leichten Verletzungen davon... Auf Höhe des Dreiecks Starnberg verlor er auf der linken Spur die Kontrolle über sein Auto. Er kam ins Schleudern, schoss rechts über einen Grünstreifen und kam auf dem Zubringer aus Starnberg wieder auf die Fahrbahn. Dort rammte er die 67-jährige Weilheimerin in ihrem Toyota... Zeugen vor Ort schätzen, dass der Sportwagen mit rund 300 Kilometer pro Stunde unterwegs war... Ein Zeuge hatte seinen Tempomat auf 140 Stundenkilometer eingestellt und war von dem Sportwagen überholt worden. "Er schätzt, der Porsche war doppelt so schnell," sagt Buck. Und: "...Schneller wie 160 Kilometer pro Stunde ist hier absolut unangemessen.". [Translation: deputy commander of the fire brigade from Hohenschaeftlarn county (Munich), Daniel Buck...was one of the first with his colleagues at the accident site where a Porsche driver (age 51) bashed into the Toyota driven by a 67-year-old [[Weilheim in Oberbayern]] resident, rolling her car over several times. The woman had to be resuscitated on site but died later in hospital. The two men in the Porsche escaped with minor injuries... At the peak of the Starnberg interchange in the left lane, he lost control of his car. He went into a skid, shot right through a grass strip to ram the 67-year-old Weilheimer resident in her Toyota... Witnesses on site estimated that the sports car was traveling about 300 kilometers per hour... One witness had his cruise control set at 140 kilometers per hour and was overtaken by the sports car. "He estimates the Porsche was twice as fast," says Buck. And: "This is simply irresponsible; even as fast as 160 kilometers per hour is inappropriate. "]}}</ref><ref>{{cite news|url=http://www.huffingtonpost.com/2011/11/19/autobahn-pileup-52-car-pileup_n_1102820.html|title=Autobahn Pileup: 52-Car German Crash Kills 3 (VIDEO)|date=2011-11-19|work=Huffington Post}}</ref> 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<ref>{{cite news|last=Kennedy|first=Maev|title='All you could hear was cars crashing': 120-car pile-up on Sheppey bridge|url=https://www.theguardian.com/uk-news/2013/sep/05/car-pileup-sheppey-bridge-kent|newspaper=The Guardian|date=2013-09-06}}</ref> or "white out" snow<ref>{{cite web|title=Girl killed, 138 cars involved in two massive pileups|website=Fox 19|date=2013-01-21|url=http://www.fox19.com/story/20639696/girl-12-killed-in-86-car-pileup-on-i-275|access-date=2013-11-06|archive-url=https://web.archive.org/web/20131109151401/http://www.fox19.com/story/20639696/girl-12-killed-in-86-car-pileup-on-i-275|url-status=dead|archive-date=2013-11-09}}</ref>), uneven roads, construction zones,<ref>{{cite web|url=http://sanatogapost.com/2013/07/10/detectives-excessive-speed-factor-in-422-crash-death/|title=Detectives: Excessive Speed Factor In 422 Crash Death|date=2013-07-10|website=The Post|access-date=2013-11-06|url-status=dead|archive-date=2015-04-02|archive-url=https://web.archive.org/web/20150402142331/http://sanatogapost.com/2013/07/10/detectives-excessive-speed-factor-in-422-crash-death/}}</ref> curves,<ref>{{cite web|url=http://www.wcpo.com/news/local-news/kyle-stein-charged-in-colerain-twp-crash-that-killed-rachel-mcgrath-and-eric-moormann|quote=[The teenage driver] lost control of the vehicle on a "curvy portion" of Sheed Road in Colerain Township and struck a parked Ford Titanium. The crash killed both passengers, [the driver] was traveling in excess of the posted {{cvt|35|mph}} speed limit to "catch up to a new model Audi R8 to get a better look at this costly vehicle"|title=Kyle Stein charged in Colerain Twp. crash that killed Rachel McGrath and Eric Moormann|access-date=2013-11-06|archive-date=2013-11-07|archive-url=https://web.archive.org/web/20131107232727/http://www.wcpo.com/news/local-news/kyle-stein-charged-in-colerain-twp-crash-that-killed-rachel-mcgrath-and-eric-moormann|url-status=dead}}</ref> intersections, gravel roads,<ref>{{cite web|url=http://www.freep.com/article/20131013/NEWS06/310130122/|title=Teen dies when fast Camaro crashes on gravel road in Spring Arbor Township|date=2013-10-13|website=Detroit Free press|access-date=2013-11-06|archive-date=2013-11-09|archive-url=https://web.archive.org/web/20131109160338/http://www.freep.com/article/20131013/NEWS06/310130122/|url-status=dead}}</ref> and heavy traffic.<ref>{{cite web|title=Too Fast for Conditions|publisher=Federal Motor Carrier Safety Administration (U.S. Department of Transportation)|url=https://www.fmcsa.dot.gov/about/outreach/education/driverTips/Too-Fast-for-Conditions-all.htm|archive-url=https://web.archive.org/web/20131105051614/https://www.fmcsa.dot.gov/about/outreach/education/driverTips/Too-Fast-for-Conditions-all.htm|archive-date=2013-11-05|url-status=dead|access-date=2013-10-31}}</ref> Per distance traveled, consequences of inappropriate speed are more frequent on lower speed, lower quality roads;<ref>{{cite web|quote=the SUV was traveling between {{cvt|62|mph}} and {{cvt|70|mph}} on a {{cvt|35|mph}} road before it flipped into a pond in a dark, unlit area in Warren on March 10, [2013], killing the 19-year-old driver and five of the seven boys riding with her|url=http://www.omaha.com/news/no-sign-of-alcohol-for-teens-killed-in-oh-crash/article_62561445-eb6d-593e-9100-68330df9ddc9.html|title=No sign of alcohol for 6 teens killed in OH crash|date=4 April 2013 }}</ref> in the United States, for example, the "speeding fatality rate for local roads is three times that for Interstates".<ref>{{cite web|title=Speeding Counts on All Roads|url=http://ntl.bts.gov/lib/23000/23100/23121/12SpeedCountsNumbers.pdf|quote=almost 50 percent of speeding-related fatalities occur on lower speed collector and local roads, which carry only 28.1 percent of the total vehicle miles traveled in the United States... the deadly consequences of speeding on local and collector roads becomes even more dramatic. The speeding fatality rate for local roads is three times that for Interstates|publisher=FHWA Safety (November 2000)|access-date=2013-10-14|archive-url=https://web.archive.org/web/20131016055545/http://ntl.bts.gov/lib/23000/23100/23121/12SpeedCountsNumbers.pdf|archive-date=2013-10-16|url-status=dead}}</ref>

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.<ref>{{cite web|url=https://ec.europa.eu/transport/road_safety/sites/roadsafety/files/pdf/ersosynthesis2018-speedenforcement.pdf|title=Speed Enforcement|date=2018|website=ec.europa.eu|access-date=2020-12-29}}</ref>

=== Maximum speed limits ===
[[File:Highway speed limits europe with indicator colors.svg|thumb|Maximum speed limits by country in Europe in km/h (and their matching highway signpost color)]]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 speed]] (the operating speed which no more than 15% of traffic exceeds),<ref>{{cite report|url=http://www.ite.org/standards/speed_zoning.pdf|title=Speed Zoning Information|publisher=[[Institute of Transportation Engineers]]|access-date=2009-09-17|date=2004-03-22|archive-date=2010-07-05|archive-url=https://web.archive.org/web/20100705040529/http://www.ite.org/standards/speed_zoning.pdf|url-status=dead}}</ref><ref>[https://mutcd.fhwa.dot.gov/htm/2009r1r2/part2/part2b.htm#section2B13 MUTCD Sections 2B.13-16] #12</ref><ref>{{cite web|url=https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH&sectionNum=21400|title=California Vehicle Code § 21400(b)|publisher=The State of California|access-date=2020-04-07|date=2012-01-01}}</ref> and in the US is frequently set {{cvt|4|to|8|mph|0}} below that speed.<ref>{{cite book|url=http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_504.pdf|title=NCHRP Report 504 – Design Speed, Operating Speed, and Posted Speed Practices|publisher=[[National Academies Press]]|location=[[Washington, D.C.]]|work=onlinepubs.trb.org|date=2003-10-06|author=Transportation Research Board of the National Academies|author2=Kay Fitzpatrick|author3=Paul Carlson|author4=Marcus A. Brewer|author5=Mark D. Wooldridge|author6=Shaw-Pin Miaou|author7=Texas Transportation Institute|isbn=0-309-08767-8|issn=0077-5614|archive-url=https://web.archive.org/web/20141021111234/http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_504.pdf|archive-date=2014-10-21|url-status=live|page=88|access-date=2009-09-16}}</ref> 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").<ref name="tti.tamu.edu">{{cite report|title=Speed: Understanding Design, Operating, and Posted Speed|first1=R.A.|last1=Krammes|first2=K.|last2=Fitzpatrick|first3=J.D.|last3=Blaschke|first4=D.B.|last4=Fambro|url=http://tti.tamu.edu/documents/1465-1.pdf|date=March 1996|publisher=Texas Transportation Institute|location=College Station, TX|id=Research Report 1465-1}}</ref> 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.<ref>{{cite web|url=https://azdot.gov/business/engineering-and-construction/traffic/faq/establishing-speed-limits|title=Establishing Speed Limits|website=azdot.gov}}</ref><ref>{{cite web|title=ESTABLISHING SPEED LIMITS: a case of "MAJORITY RULE"|url=https://www.ksdot.org/Assets/wwwksdotorg/bureaus/burTrafficSaf/brochures/pdf/speedlimitspb.pdf|publisher=Kansas Department of Transportation}}</ref> 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.{{Citation needed|date=October 2013}} 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.<ref>Public opposition to speed limits being set by an authority, often arise because such agency has been viewed as abusing its power—such as by arbitrary indiscretion or by creating "speed traps." Because an expert can theoretically calculate a safer speed limit, than the populace's vote by driving, it is beneficial that local governments preserve strong public trust with their integrity in speed regulation. See ''A Policy on Geometric Design of Highways and Streets,'' [[American Association of State Highway and Transportation Officials|AASHTO]], 4th Ed., 2001; {{ISBN|1-56051-156-7}}</ref><ref>{{cite web|url=https://safety.fhwa.dot.gov/uslimits/|title=USLIMITS2 - Safety - Federal Highway Administration|website=[[Federal Highway Administration|Federal Highway Administration (FHWA)]]}}</ref>

The maximum speed permitted by statute, as posted, is normally based on ideal driving conditions and the basic speed rule always applies.<ref>{{cite web|url=http://law.justia.com/cases/california/calapp2d/22/636.html|title=Riggs v. Gasser Motors, 22 Cal. App. 2d 636|publisher=Official California Appellate Reports (2nd Series, Vol. 22, p. 22)|date=1937-09-25}}</ref> Violation of the statute generally raises a [[rebuttable presumption]] [[negligence per se|of negligence]].<ref>{{cite web|date=1958-07-17|title=''Alarid v. Vanier,'' 50 Cal.2d 617|url=http://scocal.stanford.edu/opinion/alarid-v-vanier-26881|publisher=Official California Reports, 2nd Series Vol. 50, p. 617 (California Supreme Court reporter)}} See [http://www.lexisnexis.com/clients/CACourts/ Official California Reports online]</ref>

On international European roads, speed should be taken into account during the design stage.{{Citation needed|date=October 2013}}

{| class="wikitable"
|+Maximum speed recommended by international European road design standards:
!Road classification
!60&nbsp;km/h
!80&nbsp;km/h (50&nbsp;mph)
!100&nbsp;km/h (60&nbsp;mph)
!120&nbsp;km/h (75&nbsp;mph)
!140&nbsp;km/h (85&nbsp;mph)
|-
|Motorway || x || 80 || 100 || 120 || 140
|-
|Express road || 60 || 80 || 100 || 120 || x
|-
|Road || 60 || 80 || 100 || x || x
|}

===Minimum speed limits===
Some roads also have minimum speed limits, usually where slow speeds can impede traffic flow or be dangerous.<ref>{{cite book|last=Haney|first=James E.|title=The relationships between speed, speed limits, and motor vehicle accidents. An annotated bibliography|year=1974}}</ref> 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.<ref name="racfoundation" /> 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''.<ref>Hubbard, Phil. "Out of touch and out of time? The contemporary policing of sex work." Sex work now. Willan, 2013. 22-53.</ref>

===Middle speed limits===
Traffic rules limiting only middle speeds are rare. One such example exists on the [[ice road]]s in [[Estonia]], where it is advised to avoid driving at the speed of {{cvt|25|-|40|kph}} 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 {{cvt|25|kph}} and between {{cvt|40|-|70|kph}}.<ref>{{cite web|url=https://www.mnt.ee/eng/roads/road-maintenance/ice-roads|title=Traffic rules on ice roads|website=Transport Administration of the Republic of Estonia|archive-url=https://web.archive.org/web/20210126224458/https://www.mnt.ee/eng/roads/road-maintenance/ice-roads|archive-date=2021-01-26}}</ref>

=== Variable speed limits ===
[[File:Variable speed limit.jpg|thumb|upright|Example variable speed limit sign in the United States, in mph]]
[[File:Digital speed limit sign.jpeg|thumbnail|upright|Digital speed limit sign for variable speed limits]]
In Germany, the first known experiments with variable speed limit signs took place in 1965 on a {{convert|30|km|adj=on}} stretch of German motorway, the [[Bundesautobahn 8|A8]] between [[Munich]] and the border city of [[Salzburg]], Austria. Mechanically variable message signs could display speeds of 60, 80 and 100&nbsp;km/h, as well as text indicating a "danger zone" or "accident". Personnel monitored traffic using video technology and manually controlled the signage.<ref>{{citation|url=http://elib.uni-stuttgart.de/opus/volltexte/2003/1468/pdf/Dissertation_Schick.pdf|title=(translation) "Influence of Traffic Control Systems on Freeway Capacity and Stability of Traffic Flow"; Original Title "Einfluss von Streckenbeeinflussungsanlagen auf de Kapazitaet von Autobahnabschnitten sowie die Stabilitaet des Verkehrsflusses"|publisher=[[University of Stuttgart]]|date=June 2003|author=Peter Schick|access-date=2010-10-16|page=20|doi=10.18419/opus-175|isbn=9783980821841|quote=(translation) "The first experiment was carried out in 1965 on a 30 km section of the A8 from Salzburg to Munich. The system consisted of mechanically variable message signs at a distance of 2 km, which could display speeds of 60, 80 and 100 km/h, and "danger zone" and "accident." Personnel monitored traffic using video technology and manually controlled the signage. Studies reported a decrease in traffic disruptions and breakdowns, harmonization of the velocity distribution and an increase in performance (Zackor 1972, see also Chapter 3.2.2)." German text: "Die erste linienhafte Beeinflussung des Verkehrs erfolgte im Jahr 1965 durch die Errichtung einer Wechselverkehrszeichenanlage auf einem 30 km langen Abschnitt der A8 auf der Richtungsfahrbahn Salzburg – München. Die Anlage bestand aus neben der Fahrbahn angebrachten mechanischen Wechselverkehrszeichen im Abstand von 2 km, die StVO-gerechte Zeichen für die Geschwindigkeitsbegrenzungen 60, 80 und 100 km/h sowie "Gefahrstelle" und "Unfall" anzeigen konnten (Abb. 2-1). Diese Zeichen wurden vom Betreiberpersonal, das mittels Videotechnologie eine Übersicht über das Verkehrsgeschehen hatte, manuell geschaltet. Somit konnte erstmals auf einer Autobahn die Geschwindigkeit des Verkehrs beeinflusst sowie eine Unfallwarnung vorgenommen werden. Die ersten Erfahrungen und wissenschaftlichen Untersuchungen berichten von einer Abnahme der Störungen und Verkehrszusammenbrüche, einer Harmonisierung der Geschwindigkeitsverteilung sowie einer Steigerung der Leistungsfähigkeit (ZACKOR 1972, siehe auch Kapitel 3.2.2).}}</ref> 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, {{convert|1300|km}} of German motorways were equipped with such systems.<ref>{{citation|author=Ralf Schmahld|title=(translation) "20 years waiting in traffic jams"; Original Title "20 Jahre im Stau gestanden"|date=2009-08-06|url=http://www.turus.net/reise/4297-20-jahre-im-stau-gestanden.html?fontstyle=f-larger|publisher=Reise (Travel) magazine|quote=(translation) "A total of 1,300 kilometers of motorways now have traffic control systems for the harmonization of the traffic flow by speed limits and traffic warning, and the government expects to expand their use: 2500 km stretch of motorway could be controlled by these dynamic control systems." German text: "An insgesamt 1.300 Kilometern der Bundesautobahnen seien inzwischen Streckenbeeinflussungsanlagen zur Harmonisierung des Verkehrsablaufs durch Geschwindigkeitsbeschränkungen und Gefahrenwarnung installiert worden, teilt die Regierung weiter mit. 2.500 Kilometer Autobahnstrecke könnten mittels dynamischer Netzbeeinflussungsanlagen gesteuert werden"|access-date=2010-10-16}}</ref>

In the United States, heavily traveled portions of the [[New Jersey Turnpike]] 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.<ref>{{citation|url=http://ntl.bts.gov/lib/jpodocs/briefing/12164.pdf|title=Examples of Variable Speed Limit Applications. Speed Management Workshop|date=2000-01-09|publisher=[[Transportation Research Board]]. 79th Annual Meeting|author=Mark Robinson|access-date=2010-10-17|quote="New Jersey. Status: Active (installed in the late 1960s). Objective: to provide early warning to motorists of slow traffic or hazardous road conditions. Setting: Urban/Rural - New Jersey Turnpike.|archive-date=2011-09-27|archive-url=https://web.archive.org/web/20110927115419/http://ntl.bts.gov/lib/jpodocs/briefing/12164.pdf|url-status=dead}}</ref> More typically, variable speed limits are used on remote stretches of highway in the United States in areas with extreme changes in driving conditions.<ref name="ntl.bts.gov">{{cite web|url=https://ntl.bts.gov/repository-notice|title=Repository Notice - Bureau of Transportation Statistics|website=ntl.bts.gov|access-date=2019-01-01|archive-date=2019-01-02|archive-url=https://web.archive.org/web/20190102231239/https://ntl.bts.gov/repository-notice|url-status=dead}}</ref> For example, variable limits were introduced in October 2010 on a {{convert|52|mi|adj=on}} stretch of [[Interstate 80]] in [[Wyoming]], replacing the winter season speed reduction from {{cvt|75|to|65|mph}} that had been in place since 2008.<ref>{{cite web|url=http://www.ksl.com/?nid=148&sid=4399274|title=WYDOT proposes to lower I-80 speed limit|date=2008-09-29|quote=The Wyoming Department of Transportation says it plans to impose a speed limit of {{cvt|65|mph}} on a {{cvt|52|mi}} stretch of the interstate between Laramie and Rawlins. The reduction from the existing speed limit of {{cvt|75|mph}} will take effect Oct. 15 and continue for six months. Also, WYDOT intends to install variable speed-limit signs on the same stretch of highway so the limit can be lowered further because of bad weather. The section is between the Quealy Dome Interchange, {{cvt|20|mi}} west of Laramie, and the Peterson Interchange, {{cvt|22|mi}} east of Rawlins, the agency said.|publisher=[[KSL-TV]]|access-date=2010-10-16}}</ref><ref>{{cite web|url=http://www.landlinemag.com/todays_news/Daily/2010/Oct10/101110/101510-04.htm|title=Wyoming seasonal speed limit will vary with conditions|date=2010-10-15|quote=""When it’s all horizontal and drifts, it kills the visibility, and we have a horrible time trying to keep people on the road," Wyoming DOT engineer Tim McGary told Land Line Now on Sirius XM. McGary says this winter, truckers on I-80 will no longer see that {{cvt|65|mph}} seasonal speed limit between Laramie and Rawlins. Instead, the whole {{cvt|52|mi|adj=on}} stretch will have the electronic, variable speed limit signs that the DOT started installing last year. The variable signs allow the DOT to lower or raise the speed limit in {{cvt|5|mph}} increments depending on the weather conditions. And McGary says they work. The statistics are kind of showing that if we’re on top of things with our plow operators and troopers out there, and we get the speed limits reduced appropriately to the weather conditions, people are complying pretty well with that," McGary said. "Our crash rates have gone down, and we’re hoping to continue that trend.""|publisher=[[Land Line Magazine]]|access-date=2010-10-16|archive-date=2010-12-08|archive-url=https://web.archive.org/web/20101208192323/http://www.landlinemag.com/todays_news/Daily/2010/Oct10/101110/101510-04.htm|url-status=dead}}</ref> This Variable Speed Limit system has been proven effective in terms of reducing crash frequency and road closures.<ref>{{cite conference|author1=Saha, P.|author2=Young, R.|date=2014-08-01|title=Weather-Based Safety Analysis for the Effectiveness of Rural Variable Speed Limit (VSL) Corridors|conference=Transportation Research Board 93rd Annual Meeting|id=No. 14-2293|url=http://docs.trb.org/prp/15-1916.pdf|url-status=dead|archive-date=2015-02-23|archive-url=https://web.archive.org/web/20150223185553/http://docs.trb.org/prp/15-1916.pdf}}</ref><ref>{{cite report|author1=R. Young|author2=V. Sabawat|author3=P. Saha|author4=Y. Sui|date=2012-05-01|title=Rural Variable Speed Limits: Phase II|id=FHWA-WY-13/03F|url=https://rosap.ntl.bts.gov/view/dot/29333|access-date=2022-04-10}}<br />{{cite report|title=Final Report: FHWA-WY-13/03F|date=May 2013|url=http://www.dot.state.wy.us/files/live/sites/wydot/files/shared/Planning/Research/RS04210.pdf|archive-url=https://web.archive.org/web/20150522110130/http://www.dot.state.wy.us/files/live/sites/wydot/files/shared/Planning/Research/RS04210.pdf|archive-date=2015-05-22|url-status=dead|access-date=2022-04-11}}</ref> Similarly, [[Interstate 90]] at [[Snoqualmie Pass]] and other mountain passes in Washington State have variable speed limits as to slow traffic in severe winter weather.<ref name="ntl.bts.gov" /><ref>{{cite web|url=http://www.tfhrc.gov/pubrds/03jan/10.htm|title=Managing Speed|date=January–February 2003|work=Public Roads|publisher=www.tfhrc.gov|access-date=2008-07-06|archive-date=2008-09-21|archive-url=https://web.archive.org/web/20080921132642/http://www.tfhrc.gov/pubrds/03jan/10.htm|url-status=dead}}</ref> As a response to fog-induced chain-reaction collisions involving 99 vehicles in 1990, a variable speed limit system covering {{convert|19|mi}} of [[Interstate 75]] in [[Tennessee]] was implemented in fog-prone areas around the [[Hiwassee River]].<ref>{{cite web|url=https://ops.fhwa.dot.gov/weather/best_practices/casestudies/022.pdf|title=Tennessee Low Visibility Warning System|publisher=Federal Highway Administration|access-date=2010-10-17}}</ref> The [[Georgia Department of Transportation]] installed variable speed limits on part of [[Interstate 285 (Georgia)|Interstate 285]] around [[Atlanta]] in 2014. These speeds can be as low as {{cvt|35|mph}} but are generally set to {{cvt|35|mph}}.<ref>{{cite news|url=http://atlantaforward.blog.ajc.com/2014/09/29/moving-speed-limits-on-i-285/|title=Moving speed limits on I-285|date=2014-09-29|work=[[Atlanta Journal-Constitution]]|access-date=2015-08-22}}</ref> In 2016, the [[Oregon Department of Transportation]] installed a variable speed zone on a {{cvt|30|mi|adj=on}} stretch of [[Interstate 84 in Oregon|Interstate 84]] between [[Baker City, Oregon|Baker City]] 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.{{citation needed|date=January 2017}} [[Ohio]] established variable speed limits on three highways in 2017, then in 2019 granted the authority to the [[Ohio Department of Transportation]] to establish variable limits on any of its highways.<ref>{{orc|45|11|21}}(H)(3)</ref><ref>{{cite news|url=https://www.news-herald.com/news/odot-variable-speed-limits-only-used-to-improve-safety/article_5c4fcf5e-57b6-11e9-b3fb-135dccc9e4ac.html|title=ODOT: Variable speed limits only used to improve safety|last=Felton|first=Chad|date=2019-04-05|work=[[The News-Herald (Ohio)|The News-Herald]]|access-date=2019-04-06|location=Willoughby, OH}}</ref>

In the United Kingdom, a variable speed limit was introduced on part of the [[M25 motorway]] in 1995, on the busiest {{convert|14|mi|adj=on}} 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.<ref>{{citation|url=http://www.nao.org.uk/publications/nao_reports/04-05/040515.pdf|title=Report (HC 15, 2004-05): Tackling congestion by making better use of England's motorways and trunk roads (Full Report)|publisher=[[National Audit Office (United Kingdom)|National Audit Office]]|date=2004-11-26|access-date=2009-09-17|page=21|quote=The initial results of the one year trial of Variable Speed Limits indicated savings in journey times, smoother flowing traffic and a fall in the number of accidents. Based on these findings, the Agency converted the trial into a permanent facility in 1997. Variable Speed Limits have generally been popular with road users who have reported perceived benefits, including less congestion and less stressful journeys. The Agency could not prove a business case to use the measure elsewhere. Conditions at the site of the Variable Speed Limits trial were not stable before or during the trial, or in the period of extended monitoring that followed it. Traffic volumes changed and the Agency introduced new technology and new lighting and widened the motorway at both ends of the trial site, preventing it from establishing properly controlled and reliable "before and after" data to assess the measure’s impact. Without reliable data, the Agency could not prove a business case to use the measure elsewhere. As a result, in 2002 the Agency extended the Variable Speed Limits trial, at a further budgeted cost of £3.9 million, to cover an additional eight kilometres of the M25, where conditions were expected to be more stable, in order to collect sufficient before and after data to prepare a business case.|archive-date=2008-10-30|archive-url=https://web.archive.org/web/20081030122101/http://www.nao.org.uk/publications/nao_reports/04-05/040515.pdf|url-status=dead}}</ref> 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 [[M1 motorway#Widening from Junction 6a to 10|upgraded section of the M1]] between the M25 and [[Luton]] has had the capability for variable speed limits.<ref>{{cite web|url=http://www.highways.gov.uk/roads/documents/M1_Official_Completion_Ceremony.pdf|title=M1 Junctions 6A to 10 Official Completion Ceremony|publisher=Highways Agency|url-status=dead|archive-url=https://web.archive.org/web/20091115063727/http://www.highways.gov.uk/roads/documents/M1_Official_Completion_Ceremony.pdf|archive-date=2009-11-15}}</ref> In January 2010 temporary variable speed cameras on the M1 between J25 and J28 were made permanent.<ref>{{cite news|title=M1 works speed cameras will stay|work=BBC News|date=2010-01-03|url=http://news.bbc.co.uk/1/hi/england/nottinghamshire/8438375.stm|access-date=2010-04-13}}</ref>

New Zealand introduced variable speed limits in February 2001. The first installation was on the [[Ngauranga Gorge]] section of the dual carriageway on [[State Highway 1 (New Zealand)|State Highway 1]], characterized by steep terrain, numerous bends, high traffic volumes, and a higher than average accident rate. The speed limit is normally {{cvt|80|kph}}.<ref>{{cite web|url=http://www.ipenz.org.nz/ipenztg/papers/2002_pdf/31_Fergus_Turner.PDF|title=Monitoring Incident and Travel Behaviour Through the Use of ATMS Architecture|date=22–25 September 2002|quote=initial results of a Transfund Research project being undertaken to evaluate the effectiveness of Variable Message Speed Signs (VMSS) within the Ngauranga Active Traffic Management System (NATMS). NATMS is an incident based system whose objective is to facilitate the passage of traffic through a very demanding section of state highway just north of Wellington... A unique feature of the NATMS is the use of VMSS which display a mandatory speed imposed by controllers in response to an incident or prevailing traffic conditions... In February 2001 Transit New Zealand (TNZ) commissioned the operation of the Ngauranga Active Traffic Management System (NATMS) on State Highway 1, north of Wellington, New Zealand. The NATMS covers a 4 km stretch of State Highway between Johnsonville and the SH1 / SH2 Interchange. The NATMS is the first system in New Zealand to use Automatic Incident Detection (AID) and was chosen because of the challenging driving conditions which are compounded by steep terrain, numerous bends and a high degree of weaving between lanes. This, in conjunction with a volume over 60,000 vehicles per day and an accident rate higher than the national average were contributing factors in the introduction of the NATMS.|author=Andrew W Fergus and David J Turner (MWH NZ Ltd.)|access-date=2010-10-21|url-status=dead|archive-url=https://web.archive.org/web/20100805191744/http://www.ipenz.org.nz/ipenztg/papers/2002_pdf/31_Fergus_Turner.PDF|archive-date=2010-08-05}}</ref>

[[Austria]] 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 {{cvt|130|to|160|kph}}.<ref>{{cite web|url=http://oesterreich.orf.at/kaernten/stories/114065/|title=German: Ein Monat 'Tempo 160' auf der A10. English: A month of 'Tempo 160' on the A10|quote="German: Den 'Tempo 160-Test' auf der A10 bezeichnete Gorbach "allen Unkenrufen zum Trotz" als 'Meilenstein in der europäischen Verkehrspolitik'. Er betonte im Rahmen einer Pressekonferenz in Wien, dass mit Tempo 160 'nicht die Raser gefördert, sondern die Geschwindigkeit flexibilisiert' werden soll. English: '[The then Austrian Minister for Transportation Hubert] Gorbach said the 'Test Speed 160' on the A10 [motorway] was 'a milestone in European transport policy-despite all predictions to the contrary.' He said at a press conference in Vienna that a 160 limit 'does not promote speeding, but more flexible travel speeds'.|access-date=2010-04-16|archive-date=2011-07-18|archive-url=https://web.archive.org/web/20110718111933/http://oesterreich.orf.at/kaernten/stories/114065/|url-status=dead}}</ref> Then Austrian Transport Minister [[Hubert Gorbach]] called the experiment "a milestone in European transport policy-despite all predictions to the contrary"; however, the experiment was discontinued.{{Citation needed|date=June 2019}}

===Roads without speed limits===
Just over half of the [[German Autobahnen|German autobahns]] 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.<ref>{{cite web|url=http://www.etsc.eu/documents/Speed_Fact_Sheet_1.pdf|title=SPEED Fact Sheet. German Autobahn: The Speed Limit Debate|publisher=European Transport Safety Council|date=February 2008|quote=Currently, 52% of the German motorways do not have a speed limit, 15% have temporary speed limits due to weather or traffic conditions, and 33% have permanent speed limits. On unlimited sections, there is a 130 km/h recommendation.|access-date=2010-10-16|archive-url=https://web.archive.org/web/20110106022926/http://www.etsc.eu/documents/Speed_Fact_Sheet_1.pdf|archive-date=2011-01-06|url-status=dead}}</ref> 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 {{cvt|100|kph}}, which is usually reduced to {{cvt|80|kph}} at Allée-streets (roads bordered by trees or bushes on one or both sites).<ref>{{cite web|url=http://www.gesetze-im-internet.de/stvo_2013/__3.html|title=§ 3 StVO: Speed|publisher=Bundesministerium der Justiz und für Verbraucherschutz|quote=Diese Geschwindigkeitsbeschränkung gilt nicht [...] auf anderen Straßen mit Fahrbahnen für eine Richtung, die durch Mittelstreifen oder sonstige bauliche Einrichtungen getrennt sind. Sie gilt ferner nicht auf Straßen, die mindestens zwei durch Fahrstreifenbegrenzung (Zeichen 295) oder durch Leitlinien (Zeichen 340) markierte Fahrstreifen für jede Richtung haben.|access-date=2014-04-29}}</ref> 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 {{cvt|130|kph}} [and] more than 30% of motorists exceed {{cvt|150|kph}}".<ref>{{cite web|url=http://www.gera.de/fm/sixcms/193/09-04-30%20Gera%20LAP%20-%20Bericht.75277.pdf|trans-title=Noise Action Plan of Gera 2008|title=Lärmaktionsplan 2008 der Stadt Gera|quote=Die Berechnung basiert dabei auf der in Deutschland gültigen Richtgeschwindigkeit von 130 km/h. Die real gefahrene Geschwindigkeit auf "freigegebenen" Autobahnabschnitten liegt jedoch deutlich höher, wie das in Abb. 54 dargestellte Beispiel von der [[Bundesautobahn 9|A9]] im Bereich [[Niemegk]] zeigt. Die V85 liegt teilweise bei über 170 km/h. Im Schnitt fahren deutlich über 60 % der Verkehrsteilnehmer schneller als 130 km/h. Mehr als 30 % der Verkehrsteilnehmer fahren im Schnitt schneller als 150 km/h<br /> (English translation) Calculations are based on the German recommended a speed of 130 km/h. Actual driving speeds on motorway sections is much higher, as shown in Figure 54, for example, the [[Bundesautobahn 9|A9]] in [[Niemegk]]. The V85 [85th percentile speed] exceeds 170 km/h. On average, significantly more than 60% of road users exceed 130 km/h. More than 30% of motorists exceed 150 km/h.}}</ref> Measurements from the state of [[Brandenburg]] in 2006 showed average speeds of {{cvt|142|kph}} on a 6-lane section of autobahn in free-flowing conditions.<ref>{{cite web|url=http://www.mil.brandenburg.de/cms/media.php/lbm1.a.2239.de/studie_tempolimit.pdf|title=Auswirkungen eines allgemeinen Tempolimits auf Autobahnen im Land Brandenburg|date=October 2007|publisher=[[Brandenburg]]|access-date=2010-12-04|quote=(German)Auf einer 6-streifigen Autobahn ergibt sich für den Pkw-Verkehr im Mittel eine Geschwindigkeit von 142 km/h. (English)On clear stretches of 6-lane highway, cars average a speed of 142 km/h|archive-date=2012-09-07|archive-url=https://web.archive.org/web/20120907215341/http://www.mil.brandenburg.de/cms/media.php/lbm1.a.2239.de/studie_tempolimit.pdf|url-status=dead}}</ref>

Prior to [[German reunification]] in 1990, accident reduction programs in [[New states of Germany|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,<ref>{{cite web|url=https://www.sciencedaily.com/releases/1999/06/990616165539.htm|title=East German Traffic Deaths Jumped Dramatically After Reunification; Researchers Cite Rapid Increase In Young, Unskilled Drivers|website=ScienceDaily}}</ref> despite "interim arrangements [which] involved the continuation of the speed limit of {{cvt|100|kph}} on autobahns and of {{cvt|80|kph}} outside cities". An extensive program of the four ''E''s (enforcement, education, engineering, and [[Emergency medical services|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., {{cvt|130|kph}} freeway advisory limit, {{cvt|100|kph}} on other rural roads).<ref>{{cite web|url=http://www.giz.de/expertise/downloads/Fachexpertise/giz2006-en-traffic-safety-reunification.pdf|title=Traffic Safety - The German Experience after Reunification|publisher=[[Deutsche Gesellschaft für Technische Zusammenarbeit|German Society for Technical Cooperation]]|date=2004-11-06|access-date=2009-09-17|archive-date=2015-09-24|archive-url=https://web.archive.org/web/20150924022657/http://www.giz.de/expertise/downloads/Fachexpertise/giz2006-en-traffic-safety-reunification.pdf|url-status=dead}}</ref>

[[Transport in the Isle of Man#Roads|Many rural roads on the Isle of Man]] have no speed limits;<ref name="iomguide" /> a 2004 proposal to introduce general speed limits of {{cvt|60|mph}} and {{cvt|70|mph}} on [[A18 road (Isle of Man)|Mountain Road]], for safety reasons, was not pursued following consultation.<ref name="iomguide">{{cite web|url=http://www.iomguide.com/news/general-news.php?story=697|title=No All-Island Speed Limit|publisher=Isle of Man Guide|date=2004-11-06|access-date=2009-09-17}}</ref> [[Transport on the Isle of Man#Roads|Measured travel speeds on the island]] are relatively low.<ref>{{cite web|title=Transport Implications of the Isle of Man Strategic Plan: Report|publisher=JMP Consulting|date=2007-04-27|url=http://www.gov.im/lib/docs/transport/planning/publications/transportimplicationsofthestrate.pdf|access-date=2010-09-26|archive-date=2011-01-25|archive-url=https://web.archive.org/web/20110125021508/http://www.gov.im/lib/docs/transport/planning/publications/transportimplicationsofthestrate.pdf|url-status=dead}}</ref>

The Indian states of [[Andhra Pradesh]],<ref>{{cite web|url=http://aptransport.org/html/acts-rules/the_table_of_maximum_speed_limit_at_a_glance.pdf|title=The Table of Maximum Speed Limits at a Glance}}</ref> [[Maharashtra]],<ref>{{cite web|url=http://www.mahatranscom.in/faq.aspx|title=Data|access-date=2020-12-29}}</ref> and [[Telangana]]<ref>{{cite web|url=http://www.transport.telangana.gov.in/|title=TRANSPORT DEPARTMENT GOVERNMENT OF TELANGANA - INDIA|website=www.transport.telangana.gov.in}}</ref> 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]]. For example, [[Switzerland]] and [[Austria]] had no maximum restriction prior to 1973 on motorways and rural roads, but imposed a temporary {{cvt|100|kph}} maximum limit in response to higher fuel prices; the limit on motorways was increased to {{cvt|130|kph}} later in 1974.<ref>{{cite web|url=http://www.astra.admin.ch/dokumentation/00119/00214/index.html?lang=en&download=NHzLpZeg7t,lnp6I0NTU042l2Z6ln1ad1IZn4Z2qZpnO2Yuq2Z6gpJCDeX94hGym162epYbg2c_JjKbNoKSn6A--|title=The duties of the Swiss Federal Roads Office - ASTRA - Bundesamt|quote=Outside of built-up areas: Prior to 1973: no restriction 1973: 100 km/h (provisional) 1977: 100 km/h (definitive) 1985: 80 km/h (trial) 1989: 80 km/h (definitive), national referendum on 26 November 1989 Motorways: Prior to 1973: no restriction 1973: 100 km/h (temporary), due to oil crisis 1974: 130 km/h (provisional) 1977: 130 km/h (definitive) 1985: 120 km/h (trial) 1989: 120 km/h (definitive), national referendum on 26 November 1989|year=2009|access-date=2010-10-26|archive-url=https://web.archive.org/web/20110706221556/http://www.astra.admin.ch/dokumentation/00119/00214/index.html?lang=en&download=NHzLpZeg7t,lnp6I0NTU042l2Z6ln1ad1IZn4Z2qZpnO2Yuq2Z6gpJCDeX94hGym162epYbg2c_JjKbNoKSn6A--|archive-date=2011-07-06|url-status=dead}}</ref><ref>{{cite web|url=https://oesv1.orf.at/stories/358361|title=Seit 35 Jahren Tempolimit auf Autobahnen - oesterreich.ORF.at|website=oesv1.orf.at}}</ref><ref>{{cite web|url=http://www.oeamtc.at/?id=2500%2C1136024%2C%2C|title=Willkommen &#124; ÖAMTC|date=2023-12-04}}</ref>
[[File:MONTANA-PR.svg|thumb|Typical speed limit sign that one would see at the Montana state line from December 1995 to June 1999]]
[[Montana]] and [[Nevada]] 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.<ref>{{cite web|url=https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1812&context=jtrp|title=The Development of a Speed Monitoring Program for Indiana (FHWA/IN/JTRP-98/19)|author=Darren L. Jorgenson|author2=Kumares C. Sinha <!--(Joint Transportation Research Program, Purdue University)-->|date=April 2000|access-date=2010-09-26|publisher=[[Indiana Department of Transportation]]|quote=CHAPTER 1: INTRODUCTION : 1.1 Background Information "Before 1974, Interstate highways through various states had different speed limits, except Montana and Nevada, which had none."}}</ref> After the repeal of federal speed mandates in December 1995, Montana was the only state to revert to the basic rule for daylight rural speed regulation. The [[Montana Supreme Court]] 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]] requirement of the [[Montana Constitution]].<ref>{{cite web|url=https://caselaw.findlaw.com/courts/Montana|title=FindLaw's MT case and opinions|website=Findlaw}}</ref> In response, Montana's legislature imposed a {{cvt|75|mph}} limit on rural freeways in 1999.<ref>{{cite web|date=1999-05-28|title=Sky no longer the limit on 'Montanabahn'|url=https://www.deseret.com/1999/5/28/19447938/sky-no-longer-the-limit-on-montanabahn|access-date=2022-04-18|website=Deseret News}}</ref>

Australia's [[Northern Territory]] 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 [[Speed limits in Australia#NT open speed limits|open speed limit trial]].<ref>{{cite web|title=The need for speed on Stuart Highway|publisher=Australian Broadcasting Corporation (ABC)|date=2013-10-15|url=http://www.abc.net.au/local/stories/2013/10/15/3869390.htm|access-date=2020-12-07}}</ref>