Background The probability of dying by road traffic injuries at 50 km/h is 80%, even driving only a little above the speed limit, the number of fatal and serious injury crashes could be significant and affects road users’ health and quality of life.

Objective To estimate the prevalence of speeding and associated factors in two Mexican cities.

Methods As part of the Bloomberg Initiative for Global Road Safety (BIGRS), four and six rounds observational studies were carried out between November 2020 and October 2023 in two metropolitan cities on 25 different roadways, selected through stratified random sampling by municipality. A laser gun was used to measurement the speed in km/h, 981,048 vehicles were observed, total and specific prevalences of speeding, and their associated factors with 95% confidence intervals (95%CI) were estimated.

Results The average speed was 57.33 km/h (95% CI 57.30–57.36). Prevalence of speeding was 33.99% (33.90–34.08%) across ten rounds, 22.01% (21.93–22.10%) exceeded speed limits by 10% and 3.37% (3.34–3.41%) by 50%. In ridesharing vehicles was 34.86% (29.70–40.30%), motorcycles at 39.79% (38.86–40.73%) and light vehicles at 34.34% (34.25–34.44%). Multivariate regression analysis, identified variables associated to speeding: light vehicles (aOR: 1.19), local roads (aOR: 1.62), roads with two lanes (aOR: 1.63) and time from 7:15 to 9:00 (aOR: 1.22).

Conclusions If had 30 km/h speed limits on local or collector and 50 km/h on arterials roads in both cities, the prevalence of speeding would be 73% to 100%. The lack of alignment between current legislation and global best practices, and lenient penalties for exceeding speed limits, poses a significant risk to public health. The tolerance to punish speeding contribute drivers believe that the speed limit is higher that posted speed limit sign. It is essential to thoroughly review and strengthen existing legislation to reduce the excessive speed and improve the road safety.