At a self-controlled traffic signal transport planners do not specify the order and duration of green signal phases, instead they simply define the main traffic properties (e.g., which sensors measure which traffic streams, minimum green times, safety times, etc.). These properties define a framework for understanding the traffic’s dynamic behaviour. The self-controlled traffic signal uses this framework to, for example, assign one traffic stream more green time than another, or combine traffic streams flexibly to provide pedestrians priority in one instance and trams priority in another. In short, to do whatever the traffic situation requires.
The self-controlled traffic signal system works by preparing a robust traffic forecast and using a powerful optimization method to set green times. The system regulates traffic flows to minimize waiting time over the next two minutes based on current traffic conditions. Since these conditions can change quickly, for example when a pedestrian pushes a request button, the optimization and decision-making process is repeated every second