Published June 28, 2023

Arduino Smart Traffic Light

Smart Traffic upgrades the usual everyday traffic light to something modern, smart, and exceedingly useful, simply and cheaply!

BeginnerFull instructions provided1 hour1,532

Things used in this project

Hardware components

LED (generic)

Resistor 100 ohm

Ultrasonic Sensor - HC-SR04 (Generic)

Arduino UNO

Story

Although many traffic systems have been upgraded with ultrasonic sensing capabilities, many systems remain old-fashioned and outdated. This project uses the classic HC-SR04 ultrasonic sensor and a custom made traffic light case to produce a device that efficiently moves cars along an intersection, in order to minimize static, wasted time.

Step One: The Circuit

From Autodesk's Tinkercad

The circuit for the smart traffic system takes advantage of an HC-SR04 and three different color, red, yellow, and green, light-emitting diodes, or LEDs. To begin building this circuit, you must find the anode (+) and cathode (-) ends of the three LEDs. It is imperative to connect these in the correct order because connecting them incorrectly can lead to an LED burning up and becoming unusable. The standard among industry, hobby, and maker LEDs is the anode being the long lead of the LED, and the cathode being the short end of the LED. Connect the three LEDs to a resistor and GND of the Arduino. Connect the anodes to the digital I/O pins of the Arduino specified in the code (red: 8, yellow: 4, green: 13). Make the HC-SR04 connections specified in the image above and in the code.

Step Two: Device Assembly

You may choose to create a mounting stand for the traffic light and ultrasonic sensor. I would recommend 3D printing one or creating a cardboard model, as seen in the image above. A little hot-glue will do the trick. The sensor should be pointed towards the "road" that is facing the traffic light. It can be mounted with a bit of hot-glue as well, or with a 3D-printed case.

Step Three: The Software

Above is some of the code used for the smart traffic system. The code takes advantage of for loops and delays to keep certain lights on and wait for the HC-SR04 sensor to talk to the Arduino. Depending on what the value of the sensor is, the light will either remain in its certain cycle or switch to green and return to its cycle after remaining on for a duration of time. Then, after the cycle terminates, the process will repeat again. The function "ultrasonicDisplacement()" is my own and is what's used for this project's ultrasonic capabilities: it allows the sensor to operate properly.

Step Four: Going Further

Similar to my other projects, smart traffic can be scaled to a much smaller size. I would recommend creating your own 3D-printed module that has the ability to mount both the light and the HC-SR04. The wiring can be scaled down by creating your own custom PCB and a smaller microcontroller, instead of the relatively large Arduino Uno board. The ATtiny85 DIP is a good option for a smaller microcontroller that doesn't sacrifice too many pins.

I plan to update this project with a smart traffic version 2.0, which will include a custom PCB, printed 3D module, and concealed wiring.

Step Five: Discover

Check out my other projects on my dashboard:

Arduino Uno DIY Drone
Blindsight: a Wearable Device that Aids the Visually Impaired
IAADL: an Infrared Activated Automatic Door Lock
Arduino Functions Library

Check out all of my projects code at my GitHub repository.

Code

Smart Traffic

//Code produced by Daniel Ramsgard
//Initialize pins and global variables
int trig = 10;
int echo = 3;
int timeInMicro;
int distanceInCm;

void setup() {
  //Set serial-port baud rate to 9600 and pinmodes for HC-SR04
  Serial.begin(9600);
  pinMode(trig, OUTPUT);
  pinMode(echo, INPUT);
}

void loop() {
   //Not needed for program but useful for testing displacement
   //Prints displacement to serial port
   Serial.println(ultrasonicDisplacement(trig, echo));
   //Code for red light: light set to on for ten seconds unless displacement function returns <50
   //Then green light goes on
   for (int i = 0; i < 10; i++)
   {
     digitalWrite(8, HIGH);
     delay(1000);
      if (ultrasonicDisplacement(trig, echo) < 50)
      {
        digitalWrite(8, LOW);
        digitalWrite(13, HIGH);
        delay(5000);
        digitalWrite(13, LOW);
      }
      if (i == 9)
      {
        digitalWrite(8, LOW);
      }
    }
    //Code for yellow light: light set to on for seven seconds unless displacement function returns <50
    //Then green light goes on
    for (int j = 0; j < 7; j++)
    {
     digitalWrite(4, HIGH);
     delay(1000);
      if (ultrasonicDisplacement(trig, echo) < 50)
      {
        digitalWrite(4, LOW);
        digitalWrite(13, HIGH);
        delay(5000);
        digitalWrite(13, LOW);
      }
      if (j == 6)
      {
        digitalWrite(4, LOW);
      }
    }
    //Code for green light: light set to on for ten seconds
    for (int f = 0; f < 10; f++)
    {
      digitalWrite(13, HIGH);
      delay(1000);
      if (f == 9)
      {
        digitalWrite(13, LOW);
      }
    }
 }
//Code for function used for displacement
int ultrasonicDisplacement(int trig, int echo){
 //Code for HC-SR04
 int timeInMicro;
 int distanceInCm;
 digitalWrite(trig, LOW);
 delayMicroseconds(2);
 digitalWrite(trig, HIGH);
 delayMicroseconds(10);
 digitalWrite(trig, LOW);
 //Variables
 timeInMicro = pulseIn(echo, HIGH);
 distanceInCm = ((timeInMicro/29)/2);
 delay(1000);
 //Function's return value
 return distanceInCm;
}

Credits

Daniel Ramsgard

18 projects • 15 followers

I'm a freshman at UNC-Chapel Hill from NY & love Arduino, electronics, PCB design, and smart devices. www.github.com/DanielRamsgard

Arduino Smart Traffic Light

Things used in this project

Hardware components

Story

Step One: The Circuit

Step Two: Device Assembly

Step Three: The Software

Step Four: Going Further

Step Five: Discover

Schematics

Circuit Schematic

Code

Smart Traffic

Credits

Daniel Ramsgard

Comments

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Arduino Smart Traffic Light

Arduino Smart Traffic Light

Things used in this project

Hardware components

Story

Step One: The Circuit

Step Two: Device Assembly

Step Three: The Software

Step Four: Going Further

Step Five: Discover

Schematics

Circuit Schematic

Code

Smart Traffic

Credits

Daniel Ramsgard

Comments

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