Supporting the research of how 30km/h zones can help cities become more resilient

Ramboll engaged in a detailed meta-analysis supported by the Sustainable Development Foundation, examining 47 studies from over 40 European cities. The aim was to assess the effects of 30 km/h zones on urban pollution, traffic flow, noise, and road safety. The studies encompassed diverse urban contexts, including densely populated centres, school zones and metropolitan areas, covering cities like London, Bologna, Edinburgh, and Münster.

The methodology involved collecting and synthesising data from various experimental approaches and simulations. Efforts were made to integrate traffic flow measurements, air quality monitoring, and noise level assessments, providing a holistic view of the environmental and social impacts of reduced speed limits. This comprehensive approach allowed for accurate analyses that took into consideration local weather and traffic conditions.

30 km/h zones and their impact on urban resilience

Key findings from the project analysis indicate that 30 km/h zones significantly reduce the emissions of harmful pollutants, such as fine particulate matter (PM10 and PM2.5) and nitrogen oxides (NOx). Their reduction is due to smoother driving and fewer instances of sudden acceleration and braking. However, there can be a slight increase in CO2 emissions, up to 2.7% in certain contexts, especially for internal combustion vehicles designed to operate optimally at higher speeds.

The introduction of 30 km/h zones leads to a dramatic decrease in road accidents, with an up to 37% reduction in fatalities and a 38% drop in injuries, particularly near schools and in densely populated urban areas. This improvement is attributed to lower speed limits, which enhance driver reaction times and reduce stopping distances, improving pedestrian and cyclist safety.

30 km/h zones also contribute to a reduction in road noise between 2 and 4 decibels, significantly enhancing living conditions in residential areas by reducing urban stress and promoting greater well-being for residents.

The study underscores the role of 30 km/h zones in fostering more liveable and resilient cities. These zones encourage active mobility, improve public spaces, and help promote social cohesion. Experiences from cities like Barcelona, London, and Bologna show that emissions can be reduced by up to 19%, significantly benefiting air quality and urban structures when combined with sustainable mobility policies.

Keys to successful planning and implementation of 30 km/h zones

The study "Zone 30: The role of low-speed zones in improving urban air quality" was presented during the session on air quality at the Green Economy Conference in Italy in 2024.

Although the findings are encouraging , the research emphasises that the implementation of 30 km/h zones must be carried out jointly with planning of primary and secondary roads, alongside systems that encourage modal shift and the adoption of eco-driving practices. Predictive models are essential for predicting changes in traffic flows induced by 30 km/h zones. The implementation of 30 km/h zones influences citizens' behaviour significantly, which must be monitored over time as they can have significant effects on air quality and overall environmental and health benefits. Therefore, predictive models should be applied to assess the impact on air quality, in combination with air quality and traffic monitoring systems when planning and implementing 30 km/h zones.

Find the complete study on Sustainable Development Foundation’s website.