What motivated your deep dive into the systemic impacts of city-wide 30 km/h speed limits, and how do these findings contribute to broader “Vision Zero” and “Safe System” strategies across the EU?
I have been working for more than 30 years on road safety and I can tell you that just after the COVID-19 pandemic, it is the first time that we see a single measure with such a significant benefit at such a low cost. City-wide 30 km/h speed limit is the long-waited measure to improve road safety so quickly and without a big cost. So, we say today after four or five years of implementation that it is not simply a road safety measure; city-wide 30 km/h speed limit is a catalyzer for a new safe mobility culture in the cities, starting mainly in Europe. We have seen from our work that we can save up to 37% of fatalities of lives from road crashes. We have never seen such an important road safety benefit so quickly, so this is the main reason why we have taken this as a unique opportunity to make a breakthrough in road safety and promote something that will make European roads much safer. And of course, as you mentioned, this is exactly what is aligned with the broader Vision Zero and Safe System approach strategies of the European Union.
The objective of slower traffic and lower speed limits is to create a forgiving environment that protects specifically the most vulnerable road users, such as pedestrians, cyclists and motorcyclists. So, it is really a more systematic approach towards Vision Zero as we look at all road users’ safety and not only cars. Going a little bit further and taking into account crashes are a major societal problem and speeding is the main reason behind them, we know that with the 30 km/h speed limits we can effectively address this societal problem. We believe that it is time for this to no longer be solely the responsibility of cities. If the European Union, the European Commission want to work towards Vision Zero, we need to implement European rules on urban areas and 30 km/h speed limits, addressing this major societal health problem of road crashes, just as was the case with alcohol and smoking. Thus, it is time to follow the scientific evidence on the effectiveness of city-wide 30 km/h speed limits and establish standard European rules about speed limits of 30 km in all European cities.
Why hasn’t it been implemented yet all over Europe, what common implementation challenges did these cities face, and how were those barriers overcome to scale low-speed zones effectively?
We can say that the majority of cities, whether they have implemented the 30 km/h speed limit or not, have faced similar challenges. The most important one is that speeding remains today a standard and even desired behaviour among most drivers and riders, especially young people. Speeding is promoted, or at least largely tolerated by the society, the Authorities and the industry. There is little public reaction against speeding. However, while there are supporters of lower speeds, such as scientists and vulnerable road users, their voices remain weak against societies that are convinced and focused on cars, speeding and the broader culture of speed around us. So, the main challenge we face is achieving a cultural change.
Of course, there is an increasing societal debate about speeding and speed limits. There are more and more initiatives about safer and more sustainable mobility, along with new schemes for managing road infrastructure in cities. We have excellent examples from different European cities like Paris, Brussels, Spain and Wales. On one hand, they promote city-wide 30 km/h speed limits, and on the other, they encourage infrastructure for cycling and prioritize Public Transport. This represents a mobility culture change, transforming the culture of mobility both in terms of safety and travel habits. Still, it is not an easy task, especially when new measures are implemented. We have seen many reactions in Wales and Italy, where the next day, the Government announced that this responsibility will transfer from local to central competency.
The examples, along with the monitoring and evaluation of all these measures, are positive. This is the reason why we see more and more cities and countries adopting safer rules, such as the 30 km/h speed limits. For example, Greece is going to pass this rule for all its cities and Ireland has announced plans to implement the same. So, we no longer talk about cities deciding individually, but for a national rule. Again, I can give you a fundamental example about the challenges of implementing: very often we hear passenger car drivers complaining that they are safe with 50 km/h and find 30 km/h too restrictive. This might be true for passengers and occupants of cars, who are relatively safe at 50 km/h. But the new 30 km/h speed limits are intended to ensure pedestrians’, cyclists’ and motorcyclists’ safety, who are vulnerable outside cars and account for more than 70% of fatalities in cities. At the end of the day, we say to the car drivers that this measure is not only for their own benefit but mainly for the safety of people outside their cars. So, they may need to change their habits slightly, but society gains significant safety benefits. The discussion continues, there are reactions, as there are people in favor and people against this measure.
However, the success lies in strong and effective communication campaigns before, during and after implementation. We need studies beforehand to assess how the safety level and risks were before, how they were during the implementation and how they are evolving for six months, the first year or the second year, using scientific methods to demonstrate the benefits. So, it is an ongoing process which we see today that more and more cities are overcoming the barriers of inertia and they go much towards the new direction of slower speeds in the cities.
Beyond the statistical reductions in fatalities and injuries, how do city-wide speed limit policies shape citizens’ perception of safety and urban quality of life?
With the example of Brussels, we don’t only see a reduction in road fatalities, we see a completely different mobility pattern in the city. Studies show, and everyone can observe, that the number of pedestrians and cyclists has multiplied. Why is that the case in cities with 30 km/h speed limits? It is because people are not anymore afraid to go out on the roads. Cars are no longer fast-moving, heavy vehicles dominating the streets and discouraging people from walking or cycling. So, we see a totally different pattern of mobility just because of the new rules of 30 km/h speed limits.
Furthermore, studies show that after one or two years of implementing 30 km/h speed limits, we can also observe a modal shift. We see more people start using public transport, as they realize that it is not anymore useful to go with speedy cars. They can more easily walk to the bus stop or the metro, they can take Public Transport, which are also intensified. They have more space, so there is a totally different change in the mobility patterns of the city with direct effect on the quality of life. There is now more space for pedestrians and cyclists, more priority for public transport and the city is working towards the service of the people and not the service of cars. This shift also has a direct impact on the environment and energy consumption, leading to an entirely new paradigm of mobility in European cities.
What role does stakeholder alignment—among local governments, law enforcement, and civil society—play in the successful rollout and enforcement of 30 km/h zones?
Enforcement is effective, but not always well received. Therefore, Authorities and stakeholders need to find the right balance among enforcement, awareness campaigns and other measures to support behavioural change. And of course, as with any new measure, enforcement is not very strict in the beginning. In all cases, Authorities allow time for society and road users to adapt. We have seen quite interesting results, where the first period even without enforcement, with just suggestions, there was a significant percentage of the population, around 20-25%, who changed their behaviour without enforcement. But you see that 30 km/h speed limit also makes that; if some cars comply, the following cars must also comply, simply because they have no other alternative.
We have seen that without enforcement, there are around 25% lower speeds in cities which is translated into lives saved. Therefore, enforcement should be introduced progressively. Probably, in most cities, speed enforcement, especially with cameras, is gradually increasing. As more and more cameras are installed, compliance improves significantly. After 3 to 6 months, enforcement is becoming more important, and we start seeing high safety improvements, with totally different driving behaviour, lower speeds, and a noticeable reduction in fatalities and injuries on the road. This is a process that requires close cooperation between civil society and the Authorities, especially to determine how enforcement should be rolled out over time.
How do you respond to concerns that lower speed limits may increase congestion or travel times? Are these concerns supported by the data?
This is a very clear myth. We understand that people are afraid that a 30 km/h speed limit will lead to longer travel times and a lower average speed. However, this is not supported by studies, and it can be easily explained. We have to understand that during the day, there is congestion in most European cities, so the average speed is not much higher than 30 km/h anyway. In some cases, what usually happens at 30 km/h is that we rush, we go and stop at the next traffic light and then we go fast to the next traffic light. So, for the traffic flow, there is no real loss of time if we don’t rush and we go slowly to the next traffic light. Extensive traffic simulations and measurements before and after the implementation of 30 km/h speed limits have shown that the overall effect on average travel speed was more or less +2%, which is insignificant.
We have even seen that in the mid-term after about one to one and a half years that traffic becomes more fluid. This is because there are lower speed variations, less accelerations, less decelerations and less start and stops at junctions. As a result, traffic flow can actually benefit from lower speeds. So, it is really a myth that we are going to lose time because of the 30 km/h measure. I could accept that we are losing some time during night hours when there is no traffic and people could go faster Yes, in those cases, there may be a small increase in travel time. But it is right the moment that we have most of the crashes, involving cars, pedestrians, cyclists, and motorcyclists. So, even if there is some loss of time at night, it is so precious for saving lives. In any case, nighttime traffic is a minor part of overall traffic. The main part of the traffic happens during the day, and we have not seen any real negative impact on traffic efficiency during those hours.
Could you elaborate on the environmental and public health co-benefits observed after implementation – particularly lesser-known aspects like noise reduction or mental well-being?
According to a review of the implementation in 17 cities, 30 km/h speed limits have led to an average reduction in emissions of 18%, a decrease in noise pollution by an average of 2.5 decibels, which is not at all negligible, and a reduction in fuel consumption by an average of 7%. These are significant results that we cannot easily achieve with any other measure. Slowing down brings a fundamental benefit for the environment, energy consumption and noise pollution, which is something direct. But just to repeat that beyond safety, environment and energy consumption, we have seen these tremendous shifts in changing mode of transport. More people are using public transport, and there are more pedestrians and cyclists outside. This active travelling through public transport, walking and cycling brings in the mid-term and long-term important health benefits. People are moving more; they are getting healthier instead of the passive car driving. So, we see short term, mid-term and long-term benefits not only in terms of safety but also in changing the entire mobility culture towards healthier habits and a better quality of life.
Looking ahead, what policy levers or innovations do you see as key to accelerating the adoption of safe, low-speed mobility in urban Europe?
What is fundamental in policy is that we take initiatives at both national and European level. At the local level, there may be strong reactions, but if the rule comes from a higher level, such as the European Union or national governments, local Authorities can implement the 30 km/h speed limits more easily. Local Authorities know better their road network and can define the exceptions. Of course, the rules must be European; they should be national. But the implementation is local. The local Authorities can identify roads and define which road axes will have the exception of higher speed limits. So, this policy competency at a higher level makes the job of local Authorities much easier. And then of course, we are talking both at the national level, but especially at local level, that every policy should consider at the same time safety and mobility in an integrated way in the city.
Cities should redesign infrastructure with narrower lanes, wider sidewalks, protected cycle lanes and raised pedestrian crossings, adopting a comprehensive approach where the physical environment supports safe mobility. This, in turn, naturally leads to greater compliance and better behaviour from road users. And then we add smart enforcement technologies with cameras, digital fines and sometimes we can use telematics for driver behaviour and feedback to the drivers and the riders. There are new tools, including, for example, ride sharing, which are changing patterns, both in terms of mobility and safety. All these efforts should be closely monitored and accompanied by public awareness campaigns, especially during the transition. So, it is a combination of technical, behavioural and political steps that should be initially driven by the Authorities and then followed by civil society and all road users.
You’ve even run marathons to promote your 30 km/h campaign! Could you share a bit about that experience?
I have been working for more than 30 years on road safety, and I have been promoting safety for years, but I witnessed that scientific talking is not penetrating the society that efficiently. This is exactly the reason why I decided to combine my passion for road safety promotion and my passion for running. I am a Marathon runner, and I decided to run 30 Marathons in 30 months to actively promote the adoption of city-wide 30 km/h speed limits in all cities to pass the message much more clearly. And I can tell you that the reaction through the media, the scientific community and the whole society was 10 times higher (when I was talking about Marathons and speed limits) than when I was talking only about speed limits. I broadened the audience from mobility experts to the whole of society. It was a demanding challenge, especially while managing a busy work schedule and running a Marathon every month, but I succeeded in completing all of them in under 4 hours.
I was so happy for raising awareness for safer travelling among the Greek, the European and the global cities. And it was really a period of active campaigning through TV, radio and social media, reaching 500,000 page views annually and engaging an audience of more than 100,000 people. There were a lot of posts, interviews on TV, and events in several cities where I ran Marathons. I was warmly welcomed by the media, newspapers, magazines, and at presentations and conferences. I was so happy, very, very overwhelmed about the work behind the workload, but also by the results in promoting the 30 km/h speed limits. I would do it again and, of course, I will continue running Marathons and promoting road safety and 30 km/h speed limits, because it is such a big change in in our cities, in the quality of life in the cities, with such a small change in our habits. So, the Marathon continues. And I can mention that the link between running, and safety is that both in long distance in Marathon running and driving, we avoid high speeds. Steady pace wins the race applies equally for Marathons and sustainable mobility, a principle we practice every day.
Podcast in 4NewMobility Leadership Talk with Astrid Rohles, in June 2025
