Rome inaugurates Zone 30 in the center. Data in hand, let’s find out why reducing speed saves lives, doesn’t slow down traffic and improves the air we breathe.
From Thursday 15 January 2026 in Rome, the 30 km/h speed limit comes into force throughout the historic center, but the provision also extends to key arteries such as Corso Vittorio Emanuele and via del Teatro Marcello. The objective of the Capitoline Council is drastic: to halve road deaths in an area where coexistence between cars, tourists and residents is now at the limit of sustainability.
Slow traffic? Of course!
As we have already had the opportunity to explain in the past on these pages, the choice to lower speed limits is not a political whim, but a necessity dictated (also) by science. Yet the public debate remains heated: many citizens fear that the city will end up paralyzed. In reality, physics suggests the exact opposite.
Limiting the maximum speed to 30 km/h not only does not lengthen travel times, but improves traffic fluidity as it reduces the “accordion” effect of sudden braking. The optimal value for vehicular flow is in fact between 30 and 35 km/h; that is, it means that, traveling at this constant pace, the same number of vehicles is moved per hour, but with much less stress and noise.
The effectiveness of this measure is now certified by an impressive amount of data. A systematic study conducted by researchers Yannis and Michelaraki in 2024, analyzing 40 different European cities (including Paris and Zurich), found for example that the introduction of “Zone 30” leads to an average reduction of 37% in deaths and 38% in injuries. That is, it means that for every three people who lost their lives on the streets before the limit, today at least one is saved.
Reducing speed protects cyclists and pedestrians
The main reason for this drop in mortality lies in the protection of so-called “vulnerable users”. Research by the University of Bologna focused on the Emilian capital has highlighted how excessive speed is the main cause of accidents involving pedestrians and cyclists. That is, it means that lowering the limit means giving those who don’t have a body shop around them the time and space necessary to avoid the impact or to survive a possible collision. At 30 km/h the braking distance is in fact only 6 metres, compared to the 16.5 needed for those traveling at 50; that is, it means that if a child crosses suddenly, a car at 30 stops in good time, while one at 50 hits him head-on.
Finally, the British experience of Bristol confirms that Zone 30 is a 360-degree public health intervention. A study by Bornioli et al. (2020) demonstrated that the general reduction in speed drastically reduced road injuries throughout the urban area. That is, it means that the measure does not only work “patchwise” in individual streets, but transforms the entire city into a safer and more livable environment. Added to the safety benefits is the climate: in Rome an estimated 19% drop in CO2 emissions and a reduction in noise of over 2 decibels, which is equivalent to perceiving “traffic halved”.
