Chapter 1
Introduction
Cars have become a very popular form of transportation. Owners of cars are not
only using their vehicle for long trips, but also for short trips like visiting family
and friends or shopping. Kolbl and Helbing say that the total average travel-
ing time is inversely proportional to the energy it takes for the traveler himself
[KH03]. The traffic density has been growing during the last decades. At some
places this becomes a problem. The traffic flow is slowing down or even blocked.
This causes not only a loss of time, but it is frustrating, harmful for the environ-
ment and economics. All improvements to the traffic flow can help and are needed
to keep up with the growing traffic density. A lot of research is done on optimiza-
tion or adaptation of traffic light controllers. Testing the efficiency or optimization
of decision variables can be done with simulations.
Carlos Gershenson proposes a solution “in which traffic lights self-organize to
improve traffic flow” [Ger05].
1.1 Simulations
Improvements to the road infrastructure are expensive and new projects chang-
ing the infrastructure need to be evaluated on their effects on traffic. Simula-
tions are very useful for such evaluations and have been used by many people
[DS04, Her04, WVVK04, Ohi97, Nag04]. It is not only possible to evaluate the
modifications under normal conditions, but specific scenarios can also easily be