Design and Implementaion of Four Way Traffic Control using TTL Logic


Here we are designing and implementing the four way traffic control system using  TTL logic.

There are different variations of traffic control. The most common ones that are seen are signs (board), road lines, islands (division between opposite lanes of vehicles), and traffic lights. The first one mentioned is easily understandable. Human sight translates a drawn sign, understands what it means and thus follows it. The second one, road lines, is also uncomplicated. A road line demarcates or delineates the allowable areas and lanes that a vehicle can occupy. And a road line shows where a car cannot go, cannot make a U-turn or overtake another vehicle. Islands do the same things.

Now a days due to ever increasing vehicles on the road, it require a efficient control on the four way junction of road. In order to find a solution to this problem the concept of an automatic traffic controller is conceived. Apart from providing efficient control of traffic, it also eliminate chance of human errors since it function automatically.


Traffic lights involve a rather complicated automated system that relies on sensors and programs. There are basically two types: the first type of traffic light has fixed time. That means, the green light may be on for a minute and off for the next few minutes while the rest of the traffic lights turn green. There is a fixed time for every street meeting at an intersection. And there is the variable type of traffic light. The variable type of traffic light relies on sensors underground that detect the flow of traffic approaching the intersection. If traffic is heavy, the green light stays longer than it would if the traffic were light. Coupled with the traffic light are the speed detector and the red light running detector. The speed detector uses a device that registers the speed of an oncoming vehicle. The latter, the red light running detector uses cameras that capture vehicles’ plates as they cross an intersection. The addition of this device was due to the rise in the number of crashes that occurred because of drivers beating the stoplight.

Basic Implementation:

The basic implementation of this project is:

1. The automatic traffic controller automatically switches on the four way junction for 8 seconds for direction control.

2. The main circuit components used are 555-Timer and 4-bit binary synchronous counter (74160).

3. The 555-Timer generates a clock signal for 8 seconds. This signal is used to clock counter circuit.

4. Binary counter is converted to 3 bit–counter to achieve 8 possible cases. The traffic light control is done by different Boolean function of logic gate.

Project Report



555 Timer IC





Circuit Diagram:

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