zones and similar 20 mph zones are speed limits used across areas of urban roads in some jurisdictions. Although these zones do have the nominal speed limit posted, speeds are generally ensured by the use of physical or psychological traffic calming measures. Limits with signs and lines only are increasingly used in the UK.
Reasons for implementation
These zones are generally introduced in residential areas as an attempt to keep road traffic speeds at a safe level. Their guiding philosophy seeks to better integrate the roadways with urban areas of bustling pedestrian activity. Streets in these zones are considered public spaces for all people except those in motor vehicles. The objective is to reduce rat running while improving the safety and standard of living in the area.
Research has shown that reducing driver speeds in built-up areas reduces injuries for all road users, including motorists, cyclists, and pedestrians. The link between vehicle speed and pedestrian crash severity has been established by research studies, with crash severity increasing as a function of motor vehicle speeds.Global Road Safety Partnership, Speed management: a road safety manual for decision-makers and practitioners, Geneva: Global Road Safety Partnership, 2008, p. 5. If a vehicle hits a pedestrian while travelling , most pedestrians will survive, often sustaining only minor injuries.
Minor increases in impact speed have been shown to have a profound effect on crash severity. At , almost all crashes result in severe injuries, and roughly half are fatal; at , 90% of crashes are fatal. The dramatic differences in fatality rates are a key part of the theory behind 20 mph and zones. Other studies have revealed that lower speeds reduce community severance caused by high-speed roads in neighbourhoods. For example, there is more neighbourhood interaction and community cohesion when speeds are reduced to .
Objectives
The objectives of the implementation of 30km/h zones are to: Provide safe street crossings Improve the quality of life Increase levels of walking and cycling Reduce obesity through increased active living Reduce rat running and cutting through traffic Reducing motor vehicle traffic volumes and speeds Reduce road crash rates, injuries, and fatalities for all road users Reduce greenhouse gas emissions, air pollution, and noise pollution Create an area where pedestrians, cyclists, and motorists coexist safely and comfortably Develop a public space that is open and safe for everyone, including people with disabilities Increase the space available for walking, biking, and people on the street to eat, play, and enjoy life Provide a safe area for children in school zones Increase the real estate values of local homes and businesses Increase the economic vitality of the area Strengthen the sense of community
Benefits Compared to normal signed but unenforced speed limits, these types of speed zones are more likely to deliver the required traffic speeds because of their traffic-calming aspects.
Reviews of formal studies in many countries have found that 20 mph zones and limits are effective in reducing accidents and injuries, traffic speed, and volume.20mph Supporting Technical Appendix Rapid Evidence Review. November 2018. Report by Atkins, AECOM, and Professor Mike Maher (UCL) https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/784907/technical-appendix-4-20mph-rapid-evidence-review.pdf20mph Research Study. Process and Impact Evaluation Headline Report. November 2018. Report by Atkins, AECOM, and Professor Mike Maher (UCL). https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/784907/technical-appendix-4-20mph-rapid-evidence-review.pdfDeveloping and implementing 20-mph speed limits in Edinburgh and Belfast: mixed-methods study. Ruth Jepson, Graham Baker, Claire Cleland, Andy Cope, Neil Craig, Charlie Foster, Ruth Hunter, Frank Kee, Michael P Kelly, Paul Kelly, Karen Milton, Glenna Nightingale, Kieran Turner, Andrew James Williams and James Woodcock. Public Health Research Volume 10 • Issue 9 • September 2022ISSN 2050-4381 https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/26263/Jepson_2022_PHR_20mph_speed_limits_CC.pdf Speed limits without changes to street layout are less effective, but still have significant benefits.LUSTRE. Lower urban speed limits in Europe. What does the evidence show? May 2023. A report in three parts: Project overview report, incorporating • Development of UK policy on 20 mph speed limits, by PACTS (Evan Webster, David Davies and Margaret Winchcomb) • Summary of European speed limit case studies, by Christer Hydén, Lund University, Sweden Paper assessing the methodological quality of studies evaluating low speed limits by Dr Rune Elvik, TOI, Norway. (Appendix 1.) Meta-analysis of the effect of 20 mph speed limits in the UK by Loughborough University (A Theofilatos, M. Quddus and M Feng). (Appendix 2.) Project team: The Parliamentary Advisory Council for Transport Safety (PACTS), Loughborough University, Lund University (Sweden), Institute of Transport Economics (Norway) and the European Transport Safety Council (ETSC). Funded by The Road Safety Trust. Published by The Parliamentary Advisory Council for Transport Safety (PACTS) Buckingham Court 78 Buckingham Gate Westminster London SW1E 6PE UK https://www.pacts.org.uk/wp-content/uploads/Lustre-Report-2023-Funded-by-the-RST.pdf
Death is much less likely if a pedestrian is hit by a car travelling at 30km/h (20 mph) than at 50 km/h (30 mph) or more. The limited evidence from existing 30km/h (20 mph) schemes shows marked reductions in deaths and casualties.
Prevalence
Europe In European countries, zones have been widely used. On September 1, 1992, the city of Graz, Austria, became the first European city to implement a citywide limit on all roads except its largest. Extensive 30 km/h zones are common throughout the Netherlands. In Switzerland, zones have been allowed by law since 1989 and were first established in Zürich in 1991.
In 2017, most or all IRTAD countries had a default speed limit in urban areas of , with various lower speeds; for instance, in the Netherlands, 70% of the urban roads are limited to .
In 2013, a network of 67 European NGOs organized a European Citizens' Initiative (ECI): "30km/h – making streets liveable", which collected signatures of support for a speed limit as the normal limit for the European Union. speed limits would then become exceptions. Local authorities would be able to decide on these exceptions and set other speed limits on their street network.
In Munich, 80% of the 2,300 kilometres of urban road network have a speed limit of or less; the remaining roads are limited to .
85% of Madrid's streets are limited to . In May 2021, the government of Pedro Sánchez rolled out a new regimen of speed limits that limited most urban streets to , some to , and the rest to , depending on the number of lanes and whether the sidewalk is physically separated from street level.
Lyon has the wider zone, with an area of across 87 km of road lanes.
In January 2021, Brussels enacted as the default maximum speed for the entire Brussels Capital Region, the largest such zone in Europe at the time. The Brussels Capital Region has an area of 162 km2.
In France, the towns with the highest length of 30 kilometre zones are Toulouse (479.5 km), Angers (461 km), Paris (396.7 km), Lorient (214.5 km), Grenoble (213.7 km), Tours (183.2 km), and Nantes (179.1 km). Montpellier planned to introduce a zone on 1 August 2021, and since 30 August 2021, Paris has had a zone in most of the city except the périphérique, the boulevards des Maréchaux, and a few other streets.
Since 30 March 2022, Lyon has had a speed limit on 84% of its streets, compared to only 37% previously. This means that 610 kilometres have a speed limit out of a total of 627 kilometres.
On 8 December 2023, Amsterdam implemented "30 km/u in de stad" (30 km/h in the city), expanding the areas in which 30 km/h would be the norm. However, the municipality stresses that this, for legal purposes, is not a '30 km/h zone'. (This term refers to a specifically defined sort of zone in Dutch traffic regulations, with different right-of-way rules than this "new" type of road.)
In January 2024, Bologna enacted 30 km/h as the default maximum speed on 70% of its streets, covering around 90% of the city population.
United Kingdom
There is significant action across the UK, both by organisations and local councils, to implement more 20 mph limits and zones in local communities. 20's Plenty for Us lists populations in UK local authorities committed to wide-area 20 mph limits at over 15 million people in March 2016, with over half of the 40 largest UK urban authorities having agreed to a total 20 mph policy. Some towns define the 20 mph zone as the general speed limit across the city, with a higher speed for main roads.
Scotland In March 2018, Edinburgh implemented a citywide network of 20mph limits. Average speeds have reduced; support for 20mph is increasing, though compliance is still imperfect; casualties have fallen. There is no evidence of traffic displacement from 20mph streets to 30mph streets.Edinburgh Council 18 August 2022. Evaluation of the 20mph Speed Limit Roll Out – Three Years Post-Implementation. Paul Lawrence, Executive Director of Place. Contact: Daisy Narayanan, Senior Manager – Placemaking and Mobility https://democracy.edinburgh.gov.uk/documents/s9840/Item%207.3%20-%20Evaluation%20of%2020mph%20with%20appendices.pdf The council of the mostly rural Scottish Borders, UK, tried a 20mph speed limit in 97 villages and towns from October 2020. Speeds reduced and remained lower for at least eight months. The largest speed reductions were in locations with higher speeds, and especially in those having mean speeds greater than 25mph before the intervention.Assessing the Impact of 20 mph Speed Limits on Vehicle Speeds in Rural Areas: The Case of the Scottish Borders. Adebola Olowosegun (Transport Research Institute, School of Computing, Engineering and Built Environment, Edinburgh Napier University, Edinburgh EH10 5DT, UK), Grigorios Fountas (Author to whom correspondence should be addressed; Department of Transportation and Hydraulic Engineering, School of Rural & Surveying Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.), and Adrian Davis (Transport Research Institute, School of Computing, Engineering and Built Environment, Edinburgh Napier University, Edinburgh EH10 5DT, UK.) Safety (journal) 2023, 9(3), 66; https://doi.org/10.3390/safety9030066 13 September 2023
Wales
In Wales, in September 2023, after supportive reviews of the literature,The state of the evidence on 20mph speed limits with regards to road safety, active travel and air pollution impacts A Literature Review of the Evidence Dr Adrian L Davis FFPH Adrian Davis Associates Consultant on Transport & Health Bristol, UK August 2018. commitment in the manifesto of the ruling Welsh Labour party, some years of successful pilot studies,Transport Research Institute. Technical Paper 101. The value of prevention – casualty reductions in switching from a 30mph to 20mph speed limit default in Wales. November 2022 https://blogs.napier.ac.uk/tri/wp-content/uploads/sites/56/2022/11/TRI-Technical-Paper-101.The-value-of-Prevention.AD_.pdf extensive consultation,Proposal to reduce speed limit to 20mph on residential streets. Last updated: 11 March 2022. Summary of responses. https://www.gov.wales/proposal-reduce-speed-limit-20mph-residential-streetsExplanatory Memorandum to the Restricted Roads (20 mph Speed Limit) (Wales) Order 2022