Street Design Tops Speed Laws To Slow Drivers

10/25/2025

There is a movement in a few world cities to slow traffic speeds to 30 km/h.

However this story from Bloomberg CityLab shows speed limits mean little but that creative street design is much more effective at slowing cars:

What we found suggests something surprising: Speed limit laws aren’t actually the best way to get residents to slow down. Drivers slowed only 2–3 km/h when limits dropped from 50 to 30 km/h, while the design of the streets played a much larger role. Narrow, enclosed streets with high building density tended to slow traffic, whereas wide, open roads with long sightlines encouraged faster driving. This suggests that design, more than legislation, sets the pace.

There are likely a few explanations for this. In many countries, particularly Italy, speed limits are considered merely a suggestion, meaning that legal changes won’t usher in cultural ones. Milan and Bologna, where speed cameras were eventually banned, offer clear examples of how difficult it can be to rely solely on punitive measures — even when noncompliance is widespread.

To read the full story, click here.