Society (and business schools) teach us that being tidy is prefered to being untidy, order trumps disorder and chaos. We strive for regularity, vs erratic and irregular behavior in business. Above all, we aim for predictability and especially control.
Dirk Helbing, a physicist at the Swiss Federal Institute of Technology (ETH) in Zurich, has been studying the seemingly chaotic movement of tens of thousands of cars on road networks. His conclusion? Complex systems seem to do better without us i.e without our helping hand of overarching control.
Problem:
Within the USA alone, the annual cost of congestion is estimated to be $63.1 billion US, caused by 3.7 billion hours of delays and 8.7 billion liters of “wasted” fuel, (according to D. Schrank and T. Lomax, Texas A & M University in College Station,The 2005 urban mobility report. Texas Transportation Institute, 2005.)
In New Scientist recently, we see:
"Although the behaviour of individuals is often simple, the collective patterns to which it leads can be counter-intuitive, making common sense a faulty guide to what might happen. For example, it is generally true that traffic jams become more likely as traffic density increases. It's not always the case, though, as Helbing's group has shown."
Counter-intuitive example:
"Consider a two-lane road carrying both cars and trucks, where the cars are moving faster on average. At low traffic densities, the cars have plenty of space to overtake and can easily pass the trucks. As the traffic density increases, drivers find it more difficult to overtake because other vehicles are in the way. However, evidence from simulations and real traffic flows shows that at a critical density of traffic, the obstruction to lane-changing begins to have a beneficial effect. Because drivers tend to stay in one lane, they disturb the flow of traffic less, leading to a higher total throughput of vehicles."
This would mean giving traffic lights a way to adapt their behaviour, which most of today's systems lack. At the moment, engineers force traffic into patterns that appear favourable. Lights on main roads stay green longer during peak hours, for example. But it's the engineers who do this tuning based on average conditions observed in the past; most traffic lights don't have the flexibility to respond to changing conditions on their own. Engineers also take some things for granted, such as the notion that lights must be managed from a central control.
Smart Solution:
Self organizing smart traffic lights
Last year, Dirk Helbing and Stefan Lämmer at the Technical University of Dresden in Germany began exploring if traffic lights could be engineered, designed or intellivated (elevate intelligence) to cut congestion and reduce fuel use.
"Lights can do a better job, Helbing and Lämmer have found, if they are given some simple operating rules and left to organise their own solution. To demonstrate this, they developed a mathematical model that assumed traffic flowed like a fluid, a well-established traffic engineering technique. The model also describes what happens at road intersections, where traffic entering from one road has to leave by another, much like fluid moving through a network of pipes.
Of course, jams can arise if traffic entering a road overloads its capacity. To avoid this, Helbing and Lämmer make the lights at each intersection respond to growing traffic pressure, like the people going through the passage. Each set of lights carries sensors that feed information about the traffic conditions at a given moment into a computer, which then calculates the flow of vehicles expected in the near future. The computer also works out how long the lights should stay green in order to clear the road and relieve the pressure. In this way, each set of lights can estimate for itself how best to adapt to the conditions expected at the next moment.
Best left alone
This isn't enough, however, because the lights might adapt too much. If they are only adapting to conditions locally, they might cause trouble further away. To avoid this, Helbing and Lämmer have devised a scheme whereby neighbouring lights share their information so that what happens around one traffic light can affect how others respond. By doing so, the self-organised lights prevent long jams from forming.
Despite the simplicity of these rules, they seem to work remarkably well. Helbing and Lämmer have demonstrated in simulations that lights operating this way should achieve a significant reduction in overall travel times and keep no one waiting at a light too long (See diagram below). Nonetheless, the behaviour of the lights doesn't generally fit with human notions of what ought to be efficient. "How long lights stay green is unpredictable," says Lämmer. Yet the average journey times go down and become more predictable."
"What's more, the scheme eliminates other irritating problems that afflict traditional traffic control. At quiet times, drivers typically have to wait far longer than is really necessary at intersections because the lights' schedules are designed to serve a large number of vehicles. And in the middle of the night, lights keep stopping cars even when there is no need. The self-organising traffic scheme eliminates these problems because the lights remain responsive to local demands, for instance sensing an approaching car and changing to green to let it through."
"Town planners are beginning to look at self-organising lights as a practical solution to looming traffic congestion. Helbing and Lämmer are working with a local traffic agency in Dresden, Germany, first to test and then hopefully to implement the idea. In early simulations based on Dresden's road layout, they have had encouraging results. "We've found significant reductions in waiting times and fuel consumption, and we can also accelerate public transport," says Lämmer. Authorities in Zurich, Switzerland, have also been taken by the idea."
So, heads up...Toronto, Kyiv and Beijing...and other traffic-prone cities--Walter Derzko
Conclusion:
"The wider lesson is that we just can't trust our intuition when it comes to the super-complex systems that we depend on today. We may never learn exactly how to control these systems in the traditional fashion and the best way to cope may be by learning new principles for letting them manage themselves." concludes New Scientist.
Source: New Scientist and Self-Control of Traffic Lights and Vehicle Flows in Urban Road Networks
Tomorrow: Adaptive Intelligent Cruise Control
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