Behavioural Design: What Urban Planners Can Learn From Sweden.

Sweden’s success in reducing its road related deaths has been a hot topic in recent months, with both the Economist blog and Fast Company featuring its successful road design. According to The Economist “Sweden’s roads have become the world’s safest”, with road deaths last year hitting a record low. Overall, the number of deaths due to road accidents in Sweden has fallen by four fifths since 1970. Despite their attempts, other developed countries such as America and those across the EU have not been as successful as Sweden in reducing road related deaths.

Sweden’s developed roads and pedestrian crossings are clearly a result of the skill and technique of its designers and urban planners, in coalition with technological advances that make progressive design possible. However, if skilled labour and technology are the sole contributing factors in reducing transport related deaths, why then, do many developed countries (which have their share of the two) still have a higher number of road related deaths in comparison to Sweden? This could be due to a number of factors, including differences in population size and geographical terrain. Another possibility is that Sweden’s urban planners and policy makers simply make a better attempt at understanding what’s behind the wheel – the human being.

Vision Zero- Loss of Life “will not be acceptable on Sweden’s roadways”

While traditional economic models focus on providing road safety at a reasonable cost, Sweden’s vision zero policy, which aims to eradicate road deaths, at its core is based on an understanding that human beings err.

One of Vision Zero’s strategic principles is:

“The traffic system has to adapt to take better account of the needs, mistakes and vulnerabilities of road users”

Based on this, the Swedish government makes it their responsibility to design a transport environment that would minimize, if not eradicate the occurrence of fatal errors that occur on-road. They blame road fatalities on the way the system has been designed, rather than casting it on the user of the system (Wadhwa, 2001). This means a shift in the emphasis from using traditional incentives and penalties to change driver’s behaviour, to actually changing the driving environment to one that will minimize the occurrence of driving errors.

Can the optimism bias steer your driving in the wrong direction?

When human beings navigate their physical environment, they experience a number of biases that may either hinder, or positively contribute to their decision making. One commonly cited decision bias in driving behaviour is the optimism bias: in the face of uncertainty, individuals are likely to perceive themselves as being less prone to negative events than others. The optimism bias affects the likelihood of individuals taking self-precautionary measures against risk (Weinstein, 1980). After the Chernobyl disaster, Polish students who perceived themselves as being invulnerable to radiation were less likely to take precautions against radiation. The optimism bias is found to be responsible for a number of risk taking behaviours while driving such as drunk driving and overtaking. If individuals believe that the chances of them getting into a fatal accident after drinking and driving are low, they are more likely to engage in this behaviour. However, the optimism bias also reduces with feedback. Specifically, if an individual is made aware of another’s preventive behaviour, the optimism bias is reduced (Weinstein, 1980). This implies that this bias is strongest when the future is uncertain.

2+1 roads: behavioural design to prevent fatal errors caused by overtaking

Overtaking is a very common type of risk taking behaviour when driving. Generally, drivers in North America tend to face accidents at the end of a passing lane, while overtaking smaller cars. Sweden experienced the same problem; however its occurrence was dramatically reduced after the introduction of the 2+1 road, a three-lane road with two lanes moving in one direction and the third moving in the opposite direction. These lanes alternate every few kilometres and are flanked by cable barriers. To get a clear picture of how these roads work, I suggest watching this video-

In this video, you can see that the two lanes narrow into one after a few kilometres. The same process occurs for the third lane in the opposite direction. From a top view, the entire layout should look like this:


Clearly, on these roads, opportunities to overtake are made evident to the driver. By giving drivers feedback through the use of alternating lanes and appropriate signage, uncertainty is reduced and so is the likelihood of risk taking behaviour. In this case, the optimism bias is addressed by designing a road environment that would minimize its negative effects. Sweden’s 2+1 roads have led to a reduction of 50% in fatal accidents, when compared to single carriageway roads.

A “Human-Centred” approach to planning-

Placing human behaviour at the core of road design clearly has its advantages- many road safety campaigners are convinced that Sweden can one day hit their “zero” target (The Economist, 2014), eliminating road deaths altogether. While this claim may seem polarized (after all, we’re not sure if these campaigners are experiencing the optimism bias themselves), overall, Sweden’s emphasis on design around human thinking and its success with the same should inspire other countries to adopt a similar “Human Centred” approach to planning. After all, understanding human behaviour only has the potential to save millions of lives every year. 


Kos & Clarke, (2001). Is optimism bias influenced by control or delay? Health education and research, 533-540.

Whitelegg & Haq (2006) Vision Zero: Adopting a Target of Zero for Road Traffic Fatalities and Serious Injuries. Stockholm Environment Institute paper.