Urban Speed Limits
Public Policy Position Adopted June 2024
WHEREAS the large majority of pedestrian and cyclist fatalities occur in urban areas, and
WHEREAS higher driving speeds lead to increases in the frequency and severity of motor vehicle crashes, and
WHEREAS speed limits in general are an effective traffic safety measure, and
WHEREAS 30 kilometer-per-hour speed limits have been particularly effective in urban environments, and
BE IT RESOLVED that the speed limit in urban environments with higher volumes of pedestrians and bicycles interacting with motor vehicles should be no more than 30 kilometers per hour (~20 miles per hour).
Rationale
Most pedestrian and cyclist fatalities occur in urban areas. While vehicle design has significantly improved over the years to mitigate injury severity in crashes between vehicles, a pedestrian or bicyclist cannot dissipate the energy of an impacting motor vehicle like another motor vehicle can for its occupants. Pedestrians and cyclists are frequently termed “vulnerable road users” in the scientific literature because of this. The World Health Organization’s 2018 Global Status Report on Road Safety found that at least 26% of all road traffic deaths were pedestrians and cyclists, and the proportion is at least 44% in Africa, though there was no breakdown between urban and rural areas. More comprehensive data from the United States Department of Transportation’s Fatality Analysis Reporting System found that 20% of motor vehicle crash deaths in 2019 were either a bicyclist or pedestrian, with more than 80% of those deaths occurring in urban areas.
Driving speed is a leading factor in both the severity and frequency of motor vehicle crashes. A 2018 comprehensive literature review noted that the traffic safety literature is replete with evidence of the strong relationship between speed and crash risk and outcome severity. Some estimates suggest that that excessive or inappropriate speed are a contributing factor in 10 to 30 percent of all road crashes. 2018 National Highway Traffic Safety Administration (NHTSA) data found 26% of people who died in motor vehicle crashes had either “racing,” “driving too fast for conditions,” or “exceeding the post speed limit” listed as a contributing factor to the crash. A technical report from the American Automobile Association (AAA) found that the risk of death for a pedestrian struck by a motor vehicle increased from 10% when the impact speed was 23 miles per hour to 50% at 42 miles per hour to 90% at 58 miles per hour. Similar increases were seen for the risk of severe injury for struck pedestrians, raising from 10% at an impact speed of 16 miles per hour to 50% at 31 miles per hour to 90% at 46 miles per hour.
Speed limits are an effective traffic safety measure. Numerous case studies, including those in Australia, Denmark, Hungary, Norway, and Sweden have demonstrated that increases in speed limits have increased the number of motor vehicle crashes and fatalities and decreases in speed limits have lowered crashes and fatalities. This was also found in the United States, where the long-term effects of the 1995 repeal of federal speed limit controls found an increase in road traffic injuries and deaths attributable to increases in speed limits. A 2019 study specifically focused on a 2011 highway speed limit increase in Kansas from 70 miles per hour to 75 miles per hour. It likewise saw increases in total crashes (27%) and fatal and injury crashes (35%) where the speed limit was increased. The World Health Organization recognizes that “setting and enforcing speed limits are two of the most effective measures in reducing road traffic injuries.”
Urban speed limits set at or near 30 kilometers per hour (~20 miles per hour) are effective in urban environments. The World Health Organization targeted three best practice criteria in assessing speed laws: presence of a national speed limit, urban speed limits of 50 kilometers per hour (with recognition of 30 kilometers per hour recommended in areas with high pedestrian activity), and the ability for local authorities to modify speed limits. As of 2018, only 46 countries met all three best practices, with high-income countries being more likely to implement these best practices than middle-income countries, and both groups being much more likely than low-income countries. Still, nations around the world have demonstrated that the implementation of reduced speed limits in urban areas, particularly those where higher numbers of pedestrians and cyclists are present, have reduced traffic-related injuries. The effects of the introduction of traffic zones of 20 miles per hour in London were assessed. Over a 20-year period, a 42% reduction was seen in road injuries and fatalities, particularly for younger children. A thorough 2015 review of scientific studies that looked at zones limited to 20 miles per hour found that such limits were effective in reducing roadway accidents and injuries. Many countries have set speed limits in school zones, where higher volumes of pedestrians and bicyclists are routinely found, of 15 to 25 miles per hour in urban and suburban areas. The European Transport Safety Council has recommended a speed limit of 30 kilometers per hour in “residential areas, areas used by many pedestrians and cyclists, and on the way to schools,” and they have suggested traffic calming measures such as roundabouts, road narrowing and curvature, and speed bumps be used with enforcement to promote compliance with the speed limit. With concern about the trade-off that would happen in commute times with lower speed limits, a 2008 review studied the impact of lowered speed limits in urban and metropolitan areas and found that speed limit reduction would have minimal impacts on individual travel times.
References
Archer, J. et al. (2008). The Impact of Lowered Speed Limits in Urban and Metropolitan Areas.
Insurance Institute for Highway Safety (2021). Fatality Facts 2019: Urban/Rural Comparison.
International Transport Forum (2018). Speed and Crash Risk.
National Highway Traffic Safety Administration (2020). Traffic Safety Facts – Speeding.
Tefft, B. (2011). Impact Speed and a Pedestrian’s Risk of Severe Injury or Death.
World Health Organization (2004). Road Safety – Speed.
World Health Organization (2018). Global Status Report on Road Safety