Is there a minimum speed in Brazil? What the law says and why there is no sign

A minimum speed limit seems counterintuitive. If the risk is in taking it, why punish those who walk slowly? The answer that legislators have given for more than 70 years is not in the speed itself, but in the difference between the speeds of cars that share the same lane.

It is the concept of speed variance. The greater the distance between the slowest and fastest car on a stretch, the more overtaking happens – and each overtaking is an opportunity for collision. The rule was born from this logic: in the United States, the Uniform Traffic Code of 1954 recommended creating speed floors where studies pointed out slow vehicles in sufficient numbers to disrupt the flow. By 1962, 41 states had already adopted the standard.

What the study found

A survey published in 2021 in the Journal of Traffic and Transportation Engineering tested the effectiveness of this signage on South Carolina’s interstate highways, where the minimum is 45 mph (72 km/h). The result dismantled part of the premise.

More than 99% of vehicles already respected the minimum speed — that is, almost no one needed that plate. The maxim, on the other hand, was ignored by more than half of the drivers. According to the authors, the speed variation was not affected by the interval signaled between minimum and maximum, and the safety evaluation brought conflicting results. The paper itself concludes that there is a lack of evidence to claim that a minimum of 45 mph improves traffic uniformity.

Physics, however, no one disputes. With an average reaction time of 0.75 seconds, doubling the speed of approach between two cars doubles the space spent before the foot reaches the brake – and the braking also lengthens.

In Brazil, the minimum exists — and it’s an account

The Brazilian Traffic Code deals with the subject in article 62: “the minimum speed may not be less than half of the maximum speed established, respecting the operational conditions of traffic and the road”. It’s not a fixed number, it’s a division. On a highway signaled at 110 km/h, the floor is 55 km/h. On a rapid transit road without signaling, where the generic ceiling of 80 km/h applies, it drops to 40 km/h. On a 60 km/h street, 30 km/h.

The punishment is in article 219. Driving below this half “slowing down or obstructing traffic” is an average infraction: R$ 130.16 and four points on the CNH. The article has two caveats. There is no infraction if traffic or weather conditions do not allow for higher speed — traffic jam, heavy rain, fog. And there is no infraction if the driver is in the right lane, intended precisely for slower vehicles.

Why You’ve Never Seen a Minimum Speed Sign

Because it does not exist in Brazilian signaling. The Brazilian Manual of Traffic Signaling provides for the R-19 sign for the maximum allowed speed, but there is no equivalent for the floor. The driver needs to look at the ceiling and divide it by two.

Inspection is equally rarefied. Contran Resolution No. 798/2020, which sets the requirements for speed meters, only deals with excess: radars are not configured to fine those who walk slowly. In practice, the fine depends on an agent on site to attest to the obstruction, in addition to regulated measuring equipment. Unusual combination.

This does not make article 62 a dead letter. It has already appeared in court decisions on rear-end collisions, in which the very low speed of the car in front weighed to remove the presumption of guilt of the person who hit behind.