Does increasing intrigue and uncertainty compromise safety?

David Engwicht

The greatest objection I get to the argument that increasing intrigue and uncertainty helps to reduce speeds is: 'But doesn't this encourage rubber-necking which we all know causes more accidents?'

Paradoxically, there are two ways to make streets safer: make them totally predictable or make them totally unpredictable.
The rubber-necking phenomena (where people looking at an accident, lose concentration and have an accident themselves) is largely a problem that happens on freeways or major roads that are designed for maximum through-put of vehicles. The design rationale for these kind of roads has been to remove all unpredictability and make them as predictable as possible. In many cases even the last elements of intrigue have been removed by segregating the road from the surroundings with noise barriers. Through the design we are saying to motorists: 'This is a predictable environment in which you are highly unlikely to encounter the unpredictable'. The motorists therefore drive accordingly. On a whole, removing the unpredictable from this environment does make it safer. However, if the motorist is suddenly confronted with the unpredictable or an element of intrigue (such as an accident, or a stray animal), they are in the wrong head-space to deal with this. There is therefore a downside to this strategy of trying to improve safety by making an environment totally predictable. It is impossible to deliver the promise of total predictability. The success of this strategy for improving safety is therefore predicated on the ability of the designer to remove all intrigue and uncertainty.

By contrast, if a motorist is driving down a residential street and sees children's toys on the side of the street, or kids playing in the street, the visual clues say 'this is a space in which the unexpected should be expected'. The motorist immediately adjusts their speed downward to accommodate the possibility of the unexpected happening. This does not mean they adjust their speed to a level that eliminates all risk. (The same people who take unacceptable risks on the freeway will take unacceptable risks in a residential street full of children.) The truth is that we all add a certain 'risk factor' to what we perceive to be ironclad safe. Make our vehicle or travel environment 'safer' and we will travel faster (we add the same amount of risk to the new safety level). But the opposite is also true. Make our travel environment feel less predictable and we will travel slower. We will still be taking the same amount of risk as before, but we will be going slower. Because we are adding the same amount of risk factor as before, we will have (on average) about the same number of 'accidents'. However, because the speed is slower the accidents are likely to be less severe.

The key to understanding why making an environment totally predictable or more unpredictable can increase safety is that motorists drive according to the visual clues as to what is the 'normative state' of their driving environment. For example, in places that have snow and ice in the winter, reported accident rates often go down because drivers modify their behavior in accordance to the new normative environment with its increased levels of risk.

This leads to three basic propositions:

1. It is a myth that the only way to increase safety is to increase predictability and to remove distractions. Increasing unpredictability and providing distractions can get motorists to slow down and take more care.

2. What makes a street environment safe or unsafe is not the degree of certainty or uncertainty but the consistency and strength of visual clues as to the 'normative state' of that space. Mixed messages — not the degree of certainty or uncertainty — is what makes an environment inherently unsafe.

3. People value intrigue and the unpredictable. Both are essential to personal and social development. It is therefore impossible, and socially unacceptable, to create a city in which these are eliminated. We are therefore compelled to find ways of using intrigue and uncertainty in the service of increased safety.

These three propositions are best illustrated with a story. Over the past few years I have conducted dozens of 'instant street reclaiming' events in neighborhoods around the world. In these events we demonstrate how neighborhood activity and neighborhood created devices can dramatically slow traffic. We never close the street to traffic, put up barricades, or use official warning signs for these events. The rationale is quite simple. We are demonstrating how neighborhood activity and car movement can coexist spontaneously in the same space (in the past, when kids played in the street, they did not have to put up official warning signs).

One of the things I learned very early from these events was that having no official warning signs actually made these events safer. Motorists see some unexpected activity in the street up ahead and a million questions start running through their head. 'What is happening? Is there an accident or is it a party? I wonder if I am allowed to proceed or should I turn around?' They immediately slow down so they can take in as many clues as possible to try and make sense of what is going on. Usually by the time they get to the actual activity zone they are going at a snails pace and inevitably stop to ask what is happening. A sign that said 'Warning, Street Party Ahead' would preempt both the intrigue and uncertainty factors. Once the questions have been answered they can get back to what they were doing before, going somewhere fast.

In one city we had a dramatic illustration of why intrigue and uncertainty can help make an environment safer. The city engineer insisted that for the instant street reclaiming event we put 271 red traffic cones down the center of the street and erect half a dozen official warning signs. Traffic would use one half the street and the residents would do the street reclaiming on the other half. It was without doubt the most dangerous street event I have ever conducted. The traffic devices told the motorists they could be certain what was their space. It was a promise of predictability and certainty. So they speed down the corridor reserved as their exclusive space. Yet this promise of certainty and predictability was a totally false promise. Just a few meters from the speeding traffic were children playing with bikes and balls.

So let me use this story to illustrate and expand the three propositions mentioned earlier.

1. It is a myth that increasing predictability is the only way to make streets safer

In this case predictability made the street less safe. Ambiguity, intrigue and uncertainty all cause people to slow down and mentally engage with their surroundings. In a normal instant street reclaiming event, lack of signage has been important in getting people to slow down. The key is engaging the motorist. For example, I argue that painting a kid's tricycle red and putting it on a post is more effective as a safety device than an official sign that says, 'Warning, Kids Play Here'. The reason is that the tricycle demands a higher level of mental engagement than the sign. Motorists must decipher the meaning for themselves. (Please note that this ceases to work if a red tricycle on a post becomes the new official sign.)

2. Mixed messages, not the degree of certainty or uncertainty, are what makes an environment unsafe

In the above story, what made the event unsafe was not that kids were playing with balls in a street. We had done that many times before in complete safety. What made the event so unsafe were the mixed messages about predictability. If the 'normative state' of a street is that the unexpected should be expected, then all of the visual clues must point in this direction.

In establishing clear signals about the normative state of a street, what is not included is often more important that what is. If the normative state is that the unexpected should be expected, then traffic control devices such as line markings, official signage, concrete islands and even first-generation traffic calming devices create a mixed message. Ambiguity and lack of clear direction can be important visual clues as to the 'normative state' of a space.

3. People value intrigue and uncertainty. We must therefore find ways of using it in the service of safety

It is true that under certain conditions it is possible to make an environment, such as a freeway, safer by making it more predictable. However, it is equally true that one can make other environments safer by increasing uncertainty. It therefore becomes a communal decision as to which strategy we use in which spaces. For thousands of years, streets have not only been a place for moment, but the stage for spontaneous neighborhood-building activity. While people highly value order and predictability in their life they also highly value the unexpected. It is therefore socially unacceptable (and a denial of basic human needs) to try and remove all distractions and uncertainty from city street and create a totally predictable environment.

In conclusion: Currently we are falling between two stools. Because the 'safety experts' believe there is only one way to make things safer (more predictability) we are trying to build a vibrant community life in streets at the same time as we are trying to make them more predictable. I would argue that this is creating mixed messages and therefore creating inherently unsafe environments. We must therefore take seriously the challenge of using humans in-built love of intrigue and the unexpected as a driver for greater safety in our cities. If we find the means to do this, we will not only make our cities safer, but much more interesting and stimulating places to live.
 
Postscript: Some time after writing this article, my daughter reported seeing some man on a TV program who, in her words, 'has stolen all your ideas'. It turned out this man was Ben Hamilton-Baillie, Loeb Fellow at the Harvard Graduate School of Design. In researching the Dutch woonerf, he discovered traffic engineers in Holland and Denmark who were deliberately introducing uncertainty into the design of junctions and spaces by removing all traffic signs and line markings as a means of improving safety. One such engineer is Hans Monderman from Friesland in Northern Holland. In the village of Makkinga, all the signs and road markings relating to traffic have been removed. Not only has this improved the physical look of the village, accidents are down by 10% and speeds have been reduced significantly. In Oosterwolle, the traffic lights have been taken out and the corner cuts removed. As a result people have begun using the intersection as a traditional town square. Hans Mondermans told Ben Hamiliton-Baillie that traffic signs insult the intelligence of the driver and that roads should "tell the story of their surroundings". In the words of Hamiliton-Baillie, 'removing certainty, consistency and clarity' can make streets safer. I had to tell my daughter that the man did not steal my ideas. If two or more people are observing human behavior, chances are they will reach the same conclusions.