Arduino-Based Smart Toll Gate Automation System with RFID, GSM, Ultrasonic Sensor and LCD Display

The Smart Toll Gate Automation System using Arduino UNO is an intelligent traffic management solution designed to automate vehicle entry and toll collection using RFID technology, ultrasonic sensing, GSM communication, servo motor barrier control, and LCD display interface. This system enhances toll booth efficiency by reducing manual intervention and enabling fast, secure vehicle authentication.

The RFID RC522 module is used to identify vehicles equipped with RFID tags. When a vehicle approaches the toll gate, the system scans the RFID card and verifies the vehicle ID against stored data. Upon successful authentication and sufficient balance confirmation (if integrated with a prepaid system), the gate automatically opens using a servo motor-controlled barrier mechanism.

The ultrasonic sensor detects the presence of a vehicle near the toll booth and ensures the barrier operates only when a vehicle is positioned correctly. The LCD display (I2C 16x2) provides real-time information such as “Scan Card,” “Processing,” “Access Granted,” “Insufficient Balance,” or “Access Denied.”

The integrated GSM module can send SMS notifications to vehicle owners confirming toll deduction or alert authorities in case of unauthorized access attempts. The push button can be used for manual override or emergency control.

This project demonstrates real-world implementation of SPI communication (RFID), UART communication (GSM), I2C display interfacing, servo motor PWM control, vehicle detection using ultrasonic sensors, and embedded automation systems. It is suitable for smart city infrastructure development and intelligent transportation systems.

Key Features

RFID-based automatic toll collection system
Servo motor-operated toll gate barrier
Ultrasonic sensor for vehicle detection
GSM-based SMS notification system
I2C 16x2 LCD real-time display
Automated toll deduction logic
Reduced traffic congestion
Expandable IoT-enabled architecture
Secure and contactless vehicle authentication

Code:

#include <SPI.h>
#include <MFRC522.h>
#include <Servo.h>
#include <LiquidCrystal_I2C.h>
#include <SoftwareSerial.h>

#define RST_PIN 9
#define SS_PIN 10
#define TRIG_PIN 6
#define ECHO_PIN 7
#define IR_PIN 4
#define SERVO_PIN 5
#define BUTTON_PIN 2
#define GSM_TX 3
#define GSM_RX 2

MFRC522 mfrc522(SS_PIN, RST_PIN);
Servo gateServo;
LiquidCrystal_I2C lcd(0x27, 16, 2);
SoftwareSerial gsm(GSM_RX, GSM_TX);

SoftwareSerial serialComm(3, 4);  // RX, TX for communication with second Arduino

// Predefined RFID Cards and Balances
struct RFIDCard {
  String uid;
  int balance;
};

RFIDCard rfidCards[] = {
  {"F3E45216", 200},
  {"A1B2C3D4", 100}
};
const int tollFee = 50;

void setup() {
  Serial.begin(9600);
  SPI.begin();
  mfrc522.PCD_Init();

  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Toll Booth Ready");

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(IR_PIN, INPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  gateServo.attach(SERVO_PIN);
  gateServo.write(0);

  gsm.begin(115200);
  serialComm.begin(9600); // Start serial communication with the second Arduino
  Serial.println("System Initialized.");
}

void loop() {
  // Detect a vehicle using the ultrasonic sensor
  if (detectVehicle()) {
    lcd.setCursor(0, 0);
    lcd.print("Vehicle Detected ");
    delay(500);
    lcd.clear();

    // Detect an RFID card
    if (mfrc522.PICC_IsNewCardPresent() && mfrc522.PICC_ReadCardSerial()) {
      String cardID = getCardID();
      int balanceIndex = getBalanceIndex(cardID);
      lcd.setCursor(0, 0);

      if (balanceIndex != -1) {
        if (rfidCards[balanceIndex].balance >= tollFee) {
          lcd.print("Pay 50 Taka?");
          Serial.println("Press the button to pay.");

          bool paymentConfirmed = false;
          unsigned long startTime = millis();
          while (millis() - startTime < 10000) {
            if (digitalRead(BUTTON_PIN) == LOW) {
              paymentConfirmed = true;
              break;
            }
          }

          if (paymentConfirmed) {
            rfidCards[balanceIndex].balance -= tollFee;
            lcd.setCursor(0, 1);
            lcd.print("Payment Success ");
            Serial.println("Payment successful.");

            // Send payment status to the second Arduino
            serialComm.println("Payment Successful");

            // Send SMS Notification
            String message = "Payment of 50 Taka successful. Remaining balance: " + String(rfidCards[balanceIndex].balance) + " Taka.";
            sendSMS("+8801743648510", message);

            openGate();
          } else {
            lcd.setCursor(0, 1);
            lcd.print("Payment Timeout");
            Serial.println("Payment timeout.");
            serialComm.println("Payment Timeout");
          }
        } else {
          lcd.print("Insufficient Bal");
          Serial.println("Insufficient balance.");
          serialComm.println("Insufficient Balance");
          delay(2000);
        }
      } else {
        lcd.print("Card Not Recognized");
        Serial.println("Card not recognized.");
        serialComm.println("Card Not Recognized");
        delay(2000);
      }
      mfrc522.PICC_HaltA();
      lcd.clear();
    }
  } else {
    lcd.setCursor(0, 0);
    lcd.print("Waiting for Car ");
    delay(500);
    lcd.clear();
  }
}

bool detectVehicle() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  long duration = pulseIn(ECHO_PIN, HIGH);
  int distance = duration * 0.034 / 2;
  return (distance < 50);
}

String getCardID() {
  String cardID = "";
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    if (mfrc522.uid.uidByte[i] < 0x10) cardID += "0";
    cardID += String(mfrc522.uid.uidByte[i], HEX);
  }
  cardID.toUpperCase();
  return cardID;
}

int getBalanceIndex(String uid) {
  for (int i = 0; i < sizeof(rfidCards) / sizeof(rfidCards[0]); i++) {
    if (rfidCards[i].uid == uid) {
      return i;
    }
  }
  return -1;
}

void openGate() {
  Serial.println("Opening gate...");
  lcd.setCursor(0, 0);
  lcd.print("Opening Gate...");
  gateServo.write(90);
  delay(5000);
  while (digitalRead(IR_PIN) == LOW);
  lcd.setCursor(0, 0);
  lcd.print("Closing Gate...");
  gateServo.write(0);
  delay(1500);
  lcd.clear();
}

void sendSMS(String phoneNumber, String message) {
  gsm.print("AT+CMGF=1\r");
  delay(100);
  gsm.print("AT+CMGS=\"");
  gsm.print(phoneNumber);
  gsm.print("\"\r");
  delay(100);
  gsm.print(message);
  delay(100);
  gsm.write(26); // CTRL+Z to send SMS
  delay(5000);
  Serial.println("SMS sent to " + phoneNumber);
}

Applications

Highway toll booth automation
Smart city traffic management systems
Parking lot access control
Automated vehicle entry systems
RFID-based transportation monitoring
Intelligent transportation system (ITS) projects

Future Enhancements

Cloud-based toll management dashboard
Automatic balance recharge integration
Number plate recognition system
ESP32 WiFi-based live monitoring
Centralized toll data server
Multi-lane toll automation system

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