For many years now improvements to traffic signal control, whether isolated or co-ordinated, have been gradual. The optimization of signal setting variables is a complex task due to the randomness of behavior of road users. Although the optimization of signal timings at isolated intersections is quite easy compared with co-ordinated intersections, it is far more of a challenge to improve performance at congested signalized intersections.
The task is to find a solution that gives markedly better performance at complex individual junctions than fixed-time control. Since 1993 researchers and traffic engineers have improved performance by adopting new techniques to try to control an intersection rather as a human being or policeman would, by using the concept of fuzzy logic.
Numerous models based on fuzzy logic have been developed by researchers around the world. Most of the early models were only theoretically or simulation-based, but in recent years, a couple of applications have been launched in different countries.
One of the most recent applications, FUSICO, is in Helsinki, Finland. The Oulunkyla site, is an isolated signalized intersection controlled by a fuzzy logic controller. The efficiency of the FUSICO system was tested with vehicle-actuated signal control and field observations.
Reduced vehicle delays
The system produced an average cut in vehicle delays of 10-20%, compared with vehicle-actuated signal control. The results suggest the FUSICO system could also serve to cut vehicle emissions and fuel consumption. Such considerations are important in a world faced with the threat of global warming and climatic changes.
The success of this FUSICO application, suggest that there are gains to be had from the adoption of fuzzy control in future management. The traffic technology industry needs to embrace the concept in order to maximize the performance of its hardware.
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