The document describes a synchronized traffic signal controller that uses digital logic gates. It uses a 555 timer chip to generate a clock signal and a 4-bit counter to cycle through the four states of the traffic signals. Boolean logic gates implement the logic to control which signals are green, yellow, or red in each state based on the counter output. The circuit provides synchronized control of multiple intersections to facilitate smooth traffic flow.

1. A
Project Report
on
SYNCHRONIZED TRAFFIC
SIGNAL CONTROLLER
Submitted
rajeev

2. G H
WEST
X
A F
W Y
B
NORTH
E
Z SOUTH
EAST
C D

3. SYNCHRONIZED TRAFFIC SIGNAL CONTROLLER
1- This controller assumes equal traffic density on the entire road.
2- This traffic controller uses digital logic, which can be easily, is
implemented by logic gates.
3- This controller is generalized one can be used for different roads with
slight modification.
4- All the traffic signals in this controller are synchronized with each other.
X, Y are used as binary variables to denote the four states of all the
signals. Letters A to H indicate the left and right sides of roads in four
directions as shown in the fig.
And the traffic movement on the roads at a specific signal (green) is
denoted by arrows in directions in which traffic can flow as shown in figure.
When one signal is green the other signals, one will be yellow from which
direction traffic will flow after it and other two will be red.
The Boolean function of green light of a signal will be same as the Boolean
function of yellow light of the other signal through which traffic will flow after
it signal and the other two red lights of remaining signals and it will be same
as for other paths.
IMPLEMENTATION:-.
Timer 555 (IC1) is wired as an astable multivibrator to generate clock signal
for the 4-bit counter 74160 (IC2). The time duration of IC1 can be adjusted

4. by varying the value of resistor R1, resistor R2, or capacitor C2 of the clock
circuit. The
‘on’ time duration T is given by the following relationship:
T = 0.695C2(R1+R2)
IC2 is wired as a 2-bit binary counter by connecting its pin 11’s output to
clear pin 1 via inverter. Binary outputs from pins 13, 14 assumed as
variables X and Y, respectively. These outputs, along with their
complimentary outputs X’, Y’ respectively, are used as inputs to the rest of
the logic circuit to realize various outputs satisfying Table 1. Pin 12 is
grounded because we require two bit counter so to convert it into 2 bit
counter. We inverted pin 11’s output and set it to clear input of counter and
grounded pin 12.
We can simulate various traffic lights using green, yellow, and red LEDs
and feed the outputs of the circuit.
The traffic signals can also be controlled manually, if desired. Any signal
state can be established by entering the binary value corresponding to that
particular state into the parallel input pins of the 2-bit counter. Similarly, the
signal can be reset at any time by providing logic 0 at the reset pin (pin 1)
of the counter using an external switch.
Equipment:-
1- 555 timer IC
2- 74160 counter IC
3- Capacitors
4- Resistors
5- 7404 inverter IC
6- 7408 AND IC

5. 7- LEDS (green,yellow,red)
TABLE 1:-
INPUT(x,y) AF/AD/AG HB/HF/HD EB/ED/EG CB/CG/CF
11 GREEN YELLOW RED RED
00 RED GREEN YELLOW RED
10 RED RED GREEN YELLOW
01 YELLOW RED RED GREEN
BOOLEAN FUNCTIONS FOR ALL THE SIGNAL CONDITIONS:-
SIGNAL REFERENCE BOOLEAN FUNCTION
GREEN AF/AD/AG X’Y’
YELLOW HB/HF/HD X’Y’
RED EB/ED/EG X’Y’
RED CB/CG/CF X’Y’
RED AF/AD/AG X’Y
GREEN HB/HF/HD X’Y
YELLOW EB/ED/EG X’Y
RED CB/CG/CF X’Y
RED AF/AD/AG XY’
RED HB/HF/HD XY’
GREEN EB/ED/EG XY’
YELLOW CB/CG/CF XY’

6. YELLOW AF/AD/AG XY
RED HB/HF/HD XY
RED EB/ED/EG XY
GREEN CB/CG/CF XY
VCC
R1 8 4
240KΩ
7 9 10 15 16
7 clk 1
IC1 IC2
R1 3 2
470KΩ 555 74160
2 11
12
6 1 5 13
C1 X
C2
8 14
10 µF .01 µF Y
X’Y’ R
S1
Y
X’Y G
R
XY’
Y
S2
G
XY
R
Y S3
G
R