roundabout solution

Let's look at a case study in embracing a new simplicity in design to deal with a complex problem. In this case the complex problem is traffic. It is complex because it involves many variables that are less than predictable. For example, the number of cars, the direction of the cars, the weather, pedestrians, road conditions, visibility, maintenance and state of equipment for management and so on. If we were to design a system whereby we encouraged the collaboration of different drivers to solve the problem of traffic flow we could do it in several ways. Lets study two: 

One way that clearly emerged is the centralized control function, whereby through the use of a light and a set of policies, drivers would be told when they could move forward, turn, must stop, wait, and yield. Moreover, enforcement mechanisms for when people chose to ignore policies are also put in place, for example a camera that catches drivers who run red lights. So it is centralized in the sense that the autonomy of the agent, the driver, is removed and replaced with the decision maker's instrument, the stop light, and the accompanying policies and enforcement mechanisms for when drivers violate explicitly stated rules like speed limits. Yet even in this relatively simple solution several problems emerge. Color blindness, means that there has to be positional context, with the green light at the top, the yellow, in the middle and the red on the bottom. Ambiguity of time conditions means that drivers need to be taught to react to things like stale green lights. Lack of context to a specific situation, means that sensors in low traffic areas have to be added in order for drivers not to wait without a clear reason. And so on and so on. With every step, there is an increase in the infrastructure cost, not to mention the cost of maintenance. Moreover system failures often result in violent collisions at perpendicular angles, or blockages, or the need for a policeman to once again centrally manage a situation.

What about a decentralized approach like the roundabout? In this situation the decision making is extended to the edge of the system, to the driver. It is their decision when to go, yield, stop etc. based on a set of simple rules. i.e.

1. Traffic in the roundabout has right of way

2. Always travel in a counter-clockwise direction in the roundabout

3. Always yield for pedestrians

4. Only enter traffic when it is clear

By forcing cars to approach in a curve it is implicitly communicated by nature of the environment that speed should be reduced. Furthermore the fact that it is curved means that collisions will occur at non perpendicular angles. There is no needless waiting time when there is no traffic. There is no need for sensors, since the driver becomes the sensor. If there is bad visibility, your reference point is the car to your left. If you are color blind, all you have to do is make sure the big gray thing on wheels is far enough away. If there is a failure due to violation of the rule, restoration of equilibrium in the system is quick, i.e. clearance of accident. The cost of the infrastructure is low, just road and the cost of maintenance is incurred cost, that which it takes to maintain the road and therefore minimal in relation to the expenditure of infrastructure. The roudabout is an example of how extending autonomy and decision making to the edge of the system, in other words decentralizing control, allows for self synchronization and provides a more economical and elegant solution to a complex problem. It is a simple embrace of a new design simplicity.