Abstract:
Traffic control and management poses a major problem in many cities, especially in rapidly growing and motorizing
cities like Nairobi, Kenya. Currently, fixed-cycle controllers are being used in all signalized intersections in Nairobi.
This has culminated in most intersections within the city almost grinding to a halt during peak hours. The efficiency
of traffic flow through an intersection depends on the phases, sequence and the timing of the traffic signals
installed. This paper proposes a fuzzy logic system to control traffic signals on a signalized intersection. The Fuzzy
Logic Controller (FLC) dynamically controls the traffic light timings and phase sequence to ensure smooth flow of
traffic, decrease traffic delays and thus increase the intersection capacity. In the design, vehicle detectors are
placed strategically upstream and downstream to determine traffic density and the delay on each approach. This
traffic data is then used by the FLC to determine whether to extend or to terminate the current green phase and to
select the appropriate phase sequence. A fuzzy logic traffic control simulation model is developed and tested
using MATLAB/ SIMULINK software. The performance of the Fuzzy Logic traffic controller is then compared to that
of the fixed-cycle controller. The performance of FLC is found to be similar to that of the fixed controller in normal
traffic conditions. However, in heavy traffic conditions, FLC results shows 25% decrease on average delay of cars
waiting at the intersection and 6% improvement on total number of cars served at the intersection over the same
simulation period compared to the fixed cycle controller. The results show that there is a huge improvement that
can be realized by using FLC in controlling traffic flow at intersections.
