Traffic calming measures


This weekend, a young mother died outside of town and two more were seriously injured.

From what I understand, two (presumably) drunk young men were racing each other on motorcycles. One of them hit a young mother driving her own motorcycle and on her way to buy food. She died. The driver and passenger on the racing motorcycle were seriously injured. The other young man drove off without helping. (We know the cousin of the woman who died and the parents of the young woman who was injured.)

This highlights the terrible road culture here, and it brings up a few things for me.


Why do they drive like that? I know a standard answer is that it’s what young men do, but there is obviously more behind it. They may do it because they don’t have a way to take out their energy and hormonal craziness in a more sane and healthy way. They may do it to show off and fuel a certain identity. They may do it to deal with stress and trauma. They may do it because it’s a part of their subculture. They also do it because they can. Here, they know they very likely won’t get in trouble. In most cases, unless something like this happens, there won’t be any consequences.


The mother who died had two children, one nine months old and one five years old. In our culture, some like to assume it’s easier for the youngest one: She won’t understand what’s happening. That’s something you would say if you think we only live from the neck up. The baby has a deep visceral bond with her mother. For her, the mother is her whole world. This loss can easily create a deep trauma for her, as it will for the older child.


What can we do about it? How can we prevent it?


In our culture, some well-meaning folks say we need education.1 They assume that information, delivered in the right way, will change the behavior of those who drive too fast and drunk. It may be one small piece of the puzzle, but it’s not enough and it’s not the most effective approach.

A general rule is that educational campaigns don’t work very well, even if they are well-designed, creative, emotional, fun, and so on

Educational campaigns work for people who take information seriously and already are motivated to do the right thing. Education tends to work for educated people with resources, but this group already often behaves responsibly and it’s not the main target group.

In general, most of us already know what to do. We know we should drive safely. We know we should eat healthy food. If we still don’t do it, it’s not for lack of education. Other factors are far stronger and more influential on our behavior.

In some cases – for instance, some teenagers – educational campaigns may even work against their purpose since people don’t like to be told what to do.

It’s better to assume that people (a) act stupidly (which is sometimes true) and (b) don’t want to do the right thing (which is sometimes the case), and create social and physical structures that bring about the behavior you want anyway. In this case, safer driving.


There is a wide range of practical traffic calming strategies.

The obvious ones are frequent speed controls, frequent drunk driving controls, and digital signs that give you immediate feedback on your speed. In Denmark, they confiscate and sell your vehicle if you drive way too fast.

Several simple road design elements require the driver to reduce speed: Speed humps, speed cushions, and speed tables are uncomfortable if you go too fast. Chicanes are elevated semi-circles located on the edge of the road to make it go in a zig-zag pattern. Medians narrow your lane. Rumble strips give visceral feedback on your speed.

Although not a traffic-calming strategy, reflectors and medians mark the middle of the road and help people stay in their lane.

Trees, bushes, and flowers planted along the road can also help calm the traffic. As can optical markings like a series of white stripes on or across the road. In some places, these can be spaced increasingly closer together to give the drivers a sense of speeding up if you want them to slow down. (The downside is that locals get used to them.)

See Speed reduction methods to promote road safety and to save lives, Finding Creative Ways to Crack Down on Speeding, and Speed Reduction Mechanisms for several of these.

A more creative one is to enroll people who drive at or below the speed limit in a lottery where they can win money. This can be done with traffic cameras or apps. Apps can also be set up so you earn points for fuel, restaurant meals, and similar when you drive at or below the speed limit.

Parking an empty police car by the road can also help, although locals will catch on and get used to it if it’s done too frequently. (Unless it’s moved to different locations and sometimes also means speed and alcohol control.)

The road can be painted in colorful patterns to slow down traffic3. In Portland, they paint mandalas in the intersections for this purpose. Crosswalks can also be painted colorfully and creatively by the community, for instance with images of plants, animals, and children.

I have selected a few examples that may work in our location, in a rural town in Latin America, and left many out.


A mix of strategies will generally work the best. A bit of education, especially in school, may not hurt but is not enough in itself. The coercive ones – controls and punishment – are in the back of the mind of everyone. Some of the design elements work for everyone since they require you to slow down. The more fun and community-oriented ones work for the ones who resonate with that and they lighten the mood that would otherwise be created by the coercive measures.


(1) As mentioned above, the ones who favor educational campaigns are often well-educated and well-meaning. They are among the few an educational campaign would actually work for, although they tend to not need it and act responsibly anyway. They assume others are like them, which is not the case. Most don’t pay attention to educational campaigns, or they quickly revert to their old behavior. Other factors play a far greater role than what educational campaigns, even the best ones, can touch in people.

(2) I have a background in environmental psychology and health psychology, with a focus on strategies to facilitate public behavioral change. (University of Utah and University of Oslo.) What works? Structural changes. What doesn’t work so well? Education.

(3) Road paintings can confuse and interest the driver so they are induced to slow down. It may not work so well if they are locals and familiar with the paintings, which is why it may be helpful to change them regularly. This can be a community art project. The paintings then also become a reminder of the community, which can help local drivers to drive more responsibly.

The image is dreamt up by me and Midjourney and is only meant to give a feel of how road paintings combined with medians, chicanes, and roundabouts may look. It’s not meant to be taken literally.

Read More