Dynamic Traffic Light Controller

Introduction

This project is to design a dynamic traffic light controller, which adopts according to real time traffic flow and then control the switching of signals according to the traffic condition. In this design, induction loops are used as vehicle detectors and the control of traffic lights is done dynamically by a fuzzy logic controller in such a way to get a smooth flow of traffic. The control signals from main controller to the controllers at each traffic light is done through wireless communication which is another significant feature in this design.

Project Scope

There are three main sub sections in the project as in names, detection, controlling and communication. Under the first section vehicles has to be detected to get a proper idea of real time traffic situation. Therefore one objective of this project is to build a system to detect vehicles in order to get information about traffic flow to implement next sections. As a vehicle detection system, induction loops have been used which is one of the most commonly used methods for vehicle detection with higher accuracy and higher durability compared to other commonly used methods.

The real time vehicle count is an important fact in analyzing the current traffic condition at a particular junction and as in this case a four-lane junction is basically considered, there are eight induction loops that are been placed as two per each lane as shown in the figure. Two of the loops of one lane are placed at a pre-determined distance based on data collected about the traffic condition of particular lanes. However fundamentally one induction loop sensor is been placed near to the intersection while other one is been placed at a pre-determined distance from this. That distance is determined according to the maximum possible traffic condition of each lane so that at all times, traffic queue is in between the two loops. The difference between the information through two induction loop sensors at one lane is been used to calculate the traffic density at a particular lane. 

Next section in the project is to build up a proper controlling methodology. For that analyzing the traffic condition at real time may pose the optimum solution for traffic congestion problem. In that case fuzzy logic is used in this project as it gives a mathematical version for representing human knowledge and experience involving indistinct concepts and also it is an effective mechanism to systematically formulate a solution to complex uncertain problems.In main controller there are separate fuzzy units for each lane and the waiting time of vehicles and traffic density at respective lane has considered as two main inputs to the unit in this project. As stated earlier queue length or traffic density is determined by the induction loop data while the waiting time is the incremental time which started from 0 at the moment red light is ON of respective lane. Then from the each fuzzy unit variable number gives as an output, after considering the inputs. And send those four variable values from each lane to the fuzzy comparator which is also in the main comparator from which gives out the most suitable next phase to be opened and also whether current green phase should terminate or continue. Using those two outputs final phase selector decide the phase which should have green light ON. Communication between detectors and the central controller will be done using wireless technology.

Conclusion

In Sri Lanka most popular method which has been used to control the traffic congestion problem in many urban cities are conventional traffic light controllers. These are incorporate with pre-determined program which is based on chronological data at particular junctions. Since traffic congestion are random and non-linear matter, those pre-programmed method have not been able to achieve the most effective signal timings which in order to get a smooth flow of vehicles at the multilane junctions. But in application this method will solve the problem in most optimum way.

Project Supervisor: Dr.Satish Namasivayam

Group members: I.L.Kumarasinghe | K.J.Lakmewan | G.P.S.Lakshan | K.A.T.Lasagani

Posted in: Researches and Projects