Editing Speed limit (section)

==Effectiveness==

===Compliance===
Speed limits are more likely to be complied with if drivers have an expectation that the speed limits will be consistently enforced.<ref>{{cite journal|last1=Bauernschuster|first1=Stefan|last2=Rekers|first2=Ramona|date=2022|title=Speed limit enforcement and road safety|url=https://www.sciencedirect.com/science/article/pii/S0047272722000652|journal=Journal of Public Economics|volume=210|page=104663|doi=10.1016/j.jpubeco.2022.104663|issn=0047-2727|hdl=10419/215026|hdl-access=free}}</ref>

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.<ref name="racfoundation" /> Speed limits also need to conform to road infrastructure, education, and enforcement activity.<ref name="racfoundation" />

{{thumb|align=center|caption=Measure of effect of speed limit reduction from 90 km/h to 80 km/h, in July 2018, on the French network<br>(ONISR, 28 janvier 2019)<ref name="onisr.securite-routiere.interieur.gouv.fr">[http://www.onisr.securite-routiere.interieur.gouv.fr/contenus/sites/default/files/2019-02/2019%2B01%2B28%2BONISR-Cerema%2B1er%2Bbilan%2Bd%2B%C3%A9tape%2Bde%2Bla%2Bmesure%2BVMA80.pdf]{{dead link|date=December 2020}}</ref>
|content={{Graph:Chart
|type=line
|width=300
|x=June, July, August, September, October, November

|xAxisAngle=-40
|y3=,82.6,82.9,83.2,83.0,83.3
|y2=87.0,82.6
|y1=78.4,75.7,76.5,76.6,77.0,77.6
|y4=90,80,,,,80
|legend=
|vAnnotatonsLine=July
|vAnnotatonsLabel=Speed limit change
|y3Title=Car speed (80 km/h speed limit)
|y2Title=Car speed (90 km/h speed limit)
|y1Title=HGV speed (80 km/h speed limit)
|y4Title=Speed limit
|yAxisMin=70
|showValues=
|xGrid=1
|yGrid=1
}}
}}

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.<ref>{{cite web|url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/743878/vehicle-speed-compliance-statistics-2017.pdf|title=Vehicle Speed Compliance Statistics|date=2017|website=assets.publishing.service.gov.uk|access-date=2020-12-29}}</ref>

{{thumb|align=center|caption=Average free flow speed in UK in 2017
|content={{Graph:Chart
|width=600
|type=rect
|x=motorway, rural single carriage, 30 mph streets, 20 mph streets
|y1=69,50,31,26
|y2=69,50,31,25
|y3=54,45,30,23
|y4=61,48,30,24
|y5=,47,29,21
|y6=,47,27,23
|y7=71,54,32,27
|hAnnotatonsLine=20,30,50,70
|hAnnotatonsLabel=20,30,50,70
|legend=
|y1Title=Cars
|y2Title=Light Commercial Vehicles
|y3Title=Articulated HGVs
|y4Title=Rigid HGVs
|y5Title=Short buses
|y6Title=Long buses
|y7Title=Motorcycles

|showValues=
}}
}}

=== Relationship with crash frequency ===
A 1998 US [[Federal Highway Administration]] 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.<ref name="BCMT26">Table 3, J. Stuster and Z. Coffman, Synthesis of Safety Research Related to Speed and Speed Management, FHWA-RD-98-154, July 1998</ref> Some states increase penalties for more serious offenses, by designating as reckless driving, speeds greatly exceeding the maximum limit.{{Citation needed|date=June 2019}}

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.<ref name="ReferenceA">{{cite web|url=https://www.itf-oecd.org/sites/default/files/docs/speed-crash-risk.pdf|title=Speed crash risk|website=itf-oecd.org|access-date=2020-12-29}}</ref>

{{thumb|align=center|caption=Relationship between change of mean speed and change of fatalities<br>Source OECD-ITF<ref name="ReferenceA"/>
|content={{Graph:Chart
|type=line
|showSymbols=true
|linewidth=0
|xAxisTitle=Mean speed changes (%)
|yAxisTitle=Change of fatalities (%)
|x=0,-7.8,-3.4,-5.6,-7.5,-8.0,-2.7,-7.7,2.6
|y1=,,,,,,,,13.4
|y2=,,-41.0,
|y3=,,,-31.4,-25.5,-35.1,
|y4=0
|y5=,,,,,,-37.7,-14.3,
|y6=,-18.2
|yGrid=true
|legend=
|y1Title=Hungary (Speed limit change, non urban roads)
|y2Title=Sweden (Speed limit change, non urban roads)
|y3Title=France (Speed camera, non urban roads)
|y4Title=Zero (No change has no effect)
|y5Title=France (Speed camera, urban roads)
|y6Title=Hungary (Speed limit change, urban roads)
}}
}}

{| class="wikitable sortable"
|+Results from lowering speed limits:<ref name="BCMT26" />
|-
! Country (year of research publication)
! width=33% | Speed limit reduction
! Reported change
|-
|Australia (1992)||{{cvt|110|to|100|kph}}||Injury crashes declined by 19%
|-
|Australia (1996)||{{cvt|5|-|20|kph}} decreases||No significant change (4% increase relative to sites not changed)
|-
|Denmark (1990)||{{cvt|60|to|50|kph}}||Fatal crashes declined by 24%<br />Injury crashes declined by 9%
|-
|Germany (1994)||{{cvt|60|to|50|kph}}||Crashes declined by 20%
|-
|Sweden (1990)||{{cvt|110|to|90|kph}}||Speeds declined by {{cvt|14|kph}}<br />Fatal crashes declined by 21%
|-
|Switzerland (1994)||{{cvt|130|to|120|kph}}||Speeds declined by {{cvt|5|kph}}<br />Fatal crashes declined by 12%
|-
|UK (1991)||{{cvt|60|to|40|mph}}||Speeds declined by {{cvt|4|mph|0}}<br />Crashes declined by 14%
|-
|US (22 states) (1992)||{{cvt|5|to|15|mph|0}} decreases||No significant changes
|-
|NYC, US||{{cvt|30|to|25|mph}} decreases||28% reduction in all fatalities and 48 percent reduction in pedestrian fatalities<ref>{{cite web|url=https://www.radionz.co.nz/news/national/367359/30km-h-speed-limit-eyed-for-all-auckland-cbd-roads|title=30km/h speed limit eyed for all Auckland CBD roads|date=26 September 2018|website=Radio New Zealand}}</ref>
|-
! Country (year)
! Speed limit reduction
! Reported change
|-
|France (2018/'19)
|Speed reduced from {{cvt|90|to|80|kph}} (-11%) since July 2018, on 400,000 kilometers of the secondary network covered by 1,000 speed cameras.<ref name="lexpress.fr">{{cite web|url=https://www.lexpress.fr/actualite/societe/trafic/80-km-h-deux-fois-plus-de-vehicules-flashes-en-juillet_2028730.html|title=80 km/h: deux fois plus de véhicules flashés en juillet|date=2018-07-31|website=LExpress.fr|language=fr|access-date=2019-06-09|archive-date=2019-06-09|archive-url=https://web.archive.org/web/20190609080008/https://www.lexpress.fr/actualite/societe/trafic/80-km-h-deux-fois-plus-de-vehicules-flashes-en-juillet_2028730.html|url-status=dead}}</ref>
Five million euros have been spent on communication to explain the benefits of the speed reduction to {{cvt|80|kph}}, using various media, including television, radio, and social media (including 2 million euros for the "13 mètres" advertising movie explaining that speed reduction reduced braking distance by {{cvt|13|m}}).<ref>{{cite web|url=https://www.lexpress.fr/actualite/societe/80-km-h-la-com-a-5-millions-d-euros_2021492.html|title=80 km/h, la com' à 5 millions d'euros|date=2018-06-29|website=LExpress.fr|language=fr}}</ref>
|Effective median speed was reduced from {{cvt|87.0|kph}} in June 2018 to {{cvt|82.6|kph}} (-5%) in July 2018. Median speed was reduced of {{cvt|3.9|kph}} (-4.5%) from {{cvt|87.0|to|83.2|kph}} in September 2018.<ref name="onisr.securite-routiere.interieur.gouv.fr"/>
France to reach its historical best year for road fatalities, stopping a sequence of five years of increasing fatalities:

* Decrease of 10.7% (from 1,188 to 1,061) of fatalities saving 127 lives during the 2018 semester on rural (non motorway) network mostly impacted by the speed decrease
* Decrease of 5.3% at national level, including roads and semesters not impacted by the speed decrease, including, mainland and DOM but also COM/TOM oversea territories.
* Decrease of 5.8% (200 lives saved) in mainland, from 3,448 to 3,248 including roads and semesters not impacted by the speed decrease;
* Decrease of fatalities by 8 from 152 in 2017 to 144 in 2018 (-5%) in DOM oversea territories where national km/h speed limits applies, while an increase of 12 fatalities from 84 to 96 (+14%) occurs in COM/TOM oversea territories where national {{cvt|80|kph}} speed limit do not apply. <br />Source: ONISR (National observatory).<ref>{{cite web|url=http://www.onisr.securite-routiere.interieur.gouv.fr/contenus/sites/default/files/2019-05/ONISR%20Accidentalit%C3%A9%20routi%C3%A8re%202018%20vMS7.pdf|title=Accidents|website=www.onisr.securite-routiere.interieur.gouv.fr|access-date=2020-12-29}}{{Dead link|date=January 2021|bot=InternetArchiveBot|fix-attempted=yes}}</ref>
* Speed excess were multiplied by 2.1 (2.4 for foreigners, 2.0 for French cars), with 260,000 additional new speed excess counted in July 2018 by the 1,100 speed cameras, with 400 act of vandalism on speed cameras during July 2018<ref name="lexpress.fr"/>
* A ''yellow vest'' revolt occurred vandalizing 80%<ref>{{cite news|url=https://www.thelocal.fr/20190522/if-your-dpartement-planning-to-scrap-frances-80kmh-limit|title=Is your département planning to scrap France's 80km/h speed limit?|date=2019-05-22|newspaper=The Local France|format=PDF|access-date=2020-12-29}}</ref> of the around 4,700<ref>{{cite web|url=https://www.french-property.com/news/travel_france/speed_camera_blackspots_2016/|title=Speed Camera Blackspots in France 2016|website=www.french-property.com|date=2018-03-07}}</ref> to 10,000 speed camera in 2018.<ref name="lexpress.fr"/>

In 2020, previous results are confirmed for the year 2019: mean car speed was reduced between 2.9 and 3.9&nbsp;km/h, while mean speed of trucks was reduced by 2&nbsp;km/h without speed limit change. By the same time, fatalities were reduce by 125 in the second semester 2018, by 84 in the first semester 2019, and 127 for the second semester 2019.<ref>{{cite web|url=https://www.onisr.securite-routiere.gouv.fr/en/knowledge-centre/evaluation/evaluation-of-the-measures/80-kmh-speed-limit-on-rural-single-carriageways|title=80 km/h speed limit on rural single carriageways &#124; French road safety observatory|website=www.onisr.securite-routiere.gouv.fr}}</ref>
However, results were not repeated in overseas territories.

Final report considered speed limit change induced a {{cvt|3.5|kph}} speed decrease and saved 349 lives during the two years which last 20 months<ref>{{cite web|url=http://www.onisr.securite-routiere.gouv.fr/sites/default/files/2020-07/2020%2007%2020%20Pr%C3%A9sentation%20ONISR%20du%20bilan%20final%20Cerema%20du%2080.pdf|archive-url=https://web.archive.org/web/20201204235518/https://www.onisr.securite-routiere.gouv.fr/sites/default/files/2020-07/2020%2007%2020%20Pr%C3%A9sentation%20ONISR%20du%20bilan%20final%20Cerema%20du%2080.pdf|url-status=dead|archive-date=2020-12-04|title=Presentation|website=www.onisr.securite-routiere.interieur.gouv.fr|access-date=2020-12-29}}</ref>
|-
|Spain (2019)
|Decrease speed from {{cvt|100|to|90|kph}}
|In Spain the year 2019 was the best year with the fewest people killed outside a built-up area.
The number of people killed outside built-up areas decreased by 7.6% while the number of people killed on regular roads decreased by 9.5%. The number of people killed in cars outside built-up areas decrease by 16% from 598 to 503.<ref>{{cite web|title=Finaliza con 1.098 fallecidos, el mínimo histórico de víctimas mortales en carretera|date=2019|website=www.dgt.es|url=http://www.dgt.es/Galerias/prensa/2020/01/mir_balance_seguridad_vial_2019.nota.pdf|language=es|archive-url=https://web.archive.org/web/20210126034152/http://www.dgt.es/Galerias/prensa/2020/01/mir_balance_seguridad_vial_2019.nota.pdf|archive-date=2021-01-26|url-status=dead|access-date=2020-12-29}}</ref>

|}
{| class="wikitable sortable"
|+Results from increasing speed limits:<ref name="BCMT26" />
|-
! Country
! Speed limit increase
! Reported change
|-
|Australia (1992)||{{cvt|100|to|110|kph}}||Injury crashes increased by 25%
|-
|Australia (Victoria) (1996)||{{cvt|5|-|20|kph}} increases||Crashes increased overall by 8%, 35% decline in zones raised from {{cvt|60|to|80|kph}}
|-
|Netherlands (2012)||{{cvt|120|to|130|kph}}||Effect as of yet unclear, more research needed
|-
|US (1989)||{{cvt|55|to|65|mph}}||Fatal crashes increased by 21%
|-
|US (1990)||{{cvt|55|to|65|mph}}||Fatal crashes increased by 22%<br />Speeding increased by 48%
|-
|US (40 states) (1990)||{{cvt|55|to|65|mph}}||Fatalities increased by 15%<br />Decrease or no effect in 12 states
|-
|US (Iowa) (1996)||{{cvt|55|to|65|mph}}||Fatal crashes increased by 36%
|-
|US (Michigan) (1991)||{{cvt|55|to|65|mph}}||Fatal and injury crashes increased significantly on rural freeways
|-
|US (Michigan) (1992)||Various||No significant changes
|-
|US (Ohio) (1992)||{{cvt|55|to|65|mph}}||Injury and property damage increased but not fatal crashes.<ref>{{cite report|url=http://pubsindex.trb.org/view.aspx?id=371649|title=EFFECTS OF THE 65-MPH SPEED LIMIT ON TRAFFIC ACCIDENTS IN OHIO|publisher=[[University of Cincinnati]]|access-date=2010-07-10|year=1992|quote=fatal accident rates on rural Interstate highways posted at 65 mph or rural non-Interstate highways posted at 55 mph had not significantly changed after the implementation of the 65-mph speed limit.}}</ref>
|-
|US (40 states) (1994)||{{cvt|55|to|65|mph}}||Statewide fatality rates decreased 3–5% (Significant in 14 of 40 states)
|-
|US (22 states) (1997)||{{cvt|5|to|15|mph|0}} increase||No significant changes
|-
|}
[[South Dakota]] increased its maximum speed limit from {{cvt|65|to|75|mph}} in 1996. Annual surveys of speed on [[South Dakota]] Interstate roads show that from 2000 to 2011, the average speed rose from {{cvt|71|to|74|mph}}.<ref>{{cite web|url=http://www.sddot.com/transportation/highways/traffic/docs/speed.pdf|title=South Dakota Speed Monitoring|publisher=[[South Dakota Department of Transportation]]|year=2012|access-date=2014-12-19
}}</ref> 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.<ref>{{cite journal|last1=Farmer|first1=Charles M.|last2=Retting|first2=Richard A.|last3=Lund|first3=Adrian K.|date=1999-09-01|title=Changes in motor vehicle occupant fatalities after repeal of the national maximum speed limit|journal=Accident Analysis & Prevention|volume=31|issue=5|pages=537–543|doi=10.1016/S0001-4575(99)00010-X|pmid=10440551}}</ref>

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.<ref group="n">{{harvtxt|Federal Highway Administration|1998|p=2}} '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 {{cvt|1|mph}} change in speed, injury accidents will change by 5 percent (3 percent for every {{cvt|1|kph}}). However, limited evidence suggests the net effect of speed limits may be positive on a system wide basis.'</ref>

Research in 1998 showed that the reduction of some {{cvt|30|mph}} United Kingdom speed limits to {{cvt|20|mph}} had achieved only a {{cvt|1|mph}} drop in speeds and no discernible reduction in accidents; {{cvt|20|mph}} speed limit zones, which use self-enforcing [[traffic calming]], achieved average speed reductions of {{cvt|10|mph}}; child pedestrian accidents were reduced by 70% and child cyclist accidents by 48%.<ref>{{cite web|url=https://publications.parliament.uk/pa/cm200102/cmhansrd/vo020131/text/20131w01.htm|title=Written Answers to Questions: Road Accidents|date=2003-01-31|work=[[Hansard]]|publisher=House of Commons|quote=TRL research on urban speed management methods published in 1998 (TRL Report 363) found only an average 1 mph drop in speeds and no discernible accident reduction in accidents in 20 mph limits using only signs. Advisory speed limits are not normally approved in England and Wales. However, the more successful 20 mph zones that use self enforcing traffic calming features achieved average speed reductions of around 10 mph which produced a 70 per cent. reduction in child pedestrian accidents and 48 per cent. reduction in child cyclist accidents.|access-date=2010-04-23|archive-date=2010-04-24|archive-url=https://web.archive.org/web/20100424050559/http://www.publications.parliament.uk/pa/cm200102/cmhansrd/vo020131/text/20131w01.htm|url-status=dead}}</ref> Zones where speeds are set at [[20 mph zone|30 km/h]] (or 20&nbsp;mph) are gaining popularity<ref>{{cite web|url=http://www.streetfilms.org/no-need-for-speed-20s-plenty-for-us/|title=Streetfilms &#124; No Need for Speed: 20's Plenty for Us}}</ref> as they are found to be effective at reducing crashes and increasing community cohesion.<ref>{{cite web|url=http://www.walk21.com/papers/Josua_Hart.pdf|access-date=2011-11-27|author=Joshua Hart|title=Driven To Excess: A Study of Motor Vehicle Impacts on Three Streets in Bristol UK|url-status=dead|archive-date=2012-04-26|archive-url=https://web.archive.org/web/20120426002544/http://www.walk21.com/papers/Josua_Hart.pdf}}</ref>

Studies undertaken in conjunction with Australia's move from {{cvt|60|kph}} speed limits to {{cvt|50|kph}} in built-up areas found that the measure was effective in reducing speed and the frequency and severity of crashes.<ref>{{cite web|url=http://www.monash.edu.au/cemo/roadsafety/abstracts_and_papers/125/hawcor.pdf|title=A 50 km/h default urban speed limit for Australia?|publisher=Monash University Accident Research Centre|access-date=2010-04-26|quote=After Norway reduced its urban speed limit from 60 km/h to 50 km/h, the average speed fell by 3.5-4 km/h, and the number of fatal accidents was reduced by 45 per cent (Norwegian Traffic Safety Handbook, cited in 9)... The bulk of the casualty crash benefit relates to the implementation of 50 km/h default speed limits on urban arterials currently zoned 60 km/h. Extending the default 50 km/h urban speed limit to all residential streets across Australia contributes about 6% of the total saving in casualty crashes.}}</ref> A study of the impact of the replacement of {{cvt|60|kph}} with {{cvt|50|kph}} speed limits in [[New South Wales]], Australia, showed only a {{cvt|0.5|kph|1}} drop in urban areas and a {{cvt|0.7|kph|1}} drop in rural areas. The report noted that widespread community compliance would require a combination of strategies including traffic calming treatments.<ref>{{cite web|url=http://www.monash.edu.au/miri/research/reports/other/nrtcspeed.html|title=Evaluation of a 50 km/h Default Urban Speed Limit for Australia|publisher=Monash University Accident Research Centre|date=November 2001|access-date=2012-09-15|quote=The trial achieved reductions in average speeds of 1.5 to 2 km/h in some councils and a 7% reduction in the number of casualties and casualty crashes in the trial LGAs compared to the rest of the State.}}</ref> 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.