Pirate Party MP shares misleading infographic on 30 km/h speed zones

Czech MP Lněnička from the Pirate Party shared an infographic on social media claiming to show the effects of introducing 30 km/h speed limits in cities. However, the data presented turned out to be inaccurate and misleading, according to PoliCheck, a program that fact-checks statements made by politicians on social media.

The infographic claimed to cover data from 40 European cities. In reality, while the underlying study did look at 40 locations, the authors were only able to compile summary figures using available data from 18 cities — and even then, not for every metric. For instance, figures on changes in fatalities are based on just seven cities, while data on air pollution and noise levels come from only five.

Cities that don't even appear in the study

The post was accompanied by an AI-generated map of Europe that contained errors. Among the cities marked on it were Prague, Warsaw, Budapest and Bucharest — none of which are actually among the 40 locations included in the study.

Lněnička herself made an additional error in her caption, stating that the number of "accidents and pedestrian collisions" had dropped by 23 percent. In fact, the study's 23% figure refers only to the broader category of accidents overall — there is no separate data showing a 23% reduction specifically in pedestrian collisions.

A shaky link between cause and effect

According to the fact-check, the study itself has serious problems establishing causality. The authors themselves acknowledge that the cities examined vary significantly in size, the extent of their speed-limit zones, and the time periods assessed, making the results difficult to interpret directly. Furthermore, some of the figures were drawn not just from scientific publications but also from the websites of various organizations, government bodies, and assorted reports.

Another weakness lies in the inconsistent observation periods used. For example, data for the Austrian city of Graz goes back as far as 1992, while for other cities the COVID-19 pandemic period played a significant role — a time when traffic was restricted, and the resulting drop in mobility alone contributed to fewer accidents and deaths, regardless of any speed limit.

The study's authors themselves stress that the findings should be treated as preliminary until longer-term data series become available: in some cities, the observation period was extremely short — sometimes just a few months or years.

Source: novinky.cz