Introduction

A Smart City Monitoring System is an IoT-based solution designed to monitor urban parameters such as traffic density, air quality, water level, waste management, and street lighting in real-time.

It integrates sensors, microcontrollers, and cloud platforms to make city management efficient, safe, and sustainable.

This project is an essential step towards smart cities, which rely on automation, data analysis, and IoT connectivity to improve urban life.

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Objective of the Project

• To monitor critical urban parameters in real-time.
• To automate city infrastructure like street lights and traffic control.
• To send alerts and reports to municipal authorities for timely action.
• To implement IoT-enabled dashboards for urban management.

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Working Principle

The Smart City Monitoring System collects data from multiple sensors deployed across the city.

How It Works

1. Air Quality Sensors (MQ135) measure pollution levels (CO2, smoke, etc.).
2. Ultrasonic sensors monitor water tanks or flood-prone areas.
3. PIR sensors detect human movement for street lighting or traffic management.
4. Data from all sensors is collected by ESP32/ESP8266 microcontrollers.
5. Information is sent to a cloud platform (ThingSpeak, Blynk, or Firebase).
6. Municipal authorities or users can view real-time data on dashboards or apps.
7. Based on sensor thresholds, automated actions are performed (turning ON/OFF lights, activating alarms, etc.).

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Components Required

• ESP32 / ESP8266 Microcontroller (multiple units for different zones)
• Air Quality Sensor (MQ135)
• Ultrasonic Sensor (HC-SR04)
• PIR Motion Sensor
• DHT11 / DHT22 (Temperature & Humidity)
• Relay Module (for street lights, alarms)
• Jumper Wires & Breadboard
• IoT Platform (ThingSpeak, Blynk, or Firebase)
• 5V Power Supply

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Circuit Diagram Idea

Since a smart city system integrates multiple sensors across locations, a simplified zone-based setup can be implemented as follows:

Zone 1: Street Lighting
ESP32 -> PIR Sensor -> Relay -> Street Lamp

Zone 2: Air Quality Monitoring
ESP32 -> MQ135 -> IoT Cloud

Zone 3: Water Level Monitoring
ESP32 -> Ultrasonic Sensor -> IoT Cloud

Zone 4: Temperature & Humidity
ESP32 -> DHT11/DHT22 -> IoT Cloud

All ESP32 units connected to Wi-Fi and send data to IoT platform

Note: Each zone can use a separate ESP32 or multiple sensors connected to a single ESP32 depending on network and range.

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Arduino/ESP32 Code Example (Air Quality + Temperature + Humidity)

#include <WiFi.h>
#include "ThingSpeak.h"
#include <DHT.h>

#define DHTPIN 4
#define DHTTYPE DHT22
#define MQ135PIN 34

DHT dht(DHTPIN, DHTTYPE);

const char* ssid = "Your_SSID";
const char* password = "Your_PASSWORD";
WiFiClient client;

unsigned long channelID = 123456;  // ThingSpeak Channel ID
const char* writeAPIKey = "YOUR_API_KEY";

void setup() {
  Serial.begin(115200);
  dht.begin();
  
  WiFi.begin(ssid, password);
  Serial.print("Connecting to Wi-Fi");
  while(WiFi.status() != WL_CONNECTED){
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected!");
  
  ThingSpeak.begin(client);
}

void loop() {
  float temp = dht.readTemperature();
  float hum = dht.readHumidity();
  int airQuality = analogRead(MQ135PIN);
  
  Serial.print("Temperature: "); Serial.println(temp);
  Serial.print("Humidity: "); Serial.println(hum);
  Serial.print("Air Quality: "); Serial.println(airQuality);
  
  ThingSpeak.setField(1, temp);
  ThingSpeak.setField(2, hum);
  ThingSpeak.setField(3, airQuality);
  
  ThingSpeak.writeFields(channelID, writeAPIKey);
  
  delay(20000); // Update every 20 seconds
}

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Code Explanation

• ESP32 connects to Wi-Fi and ThingSpeak IoT platform.
• DHT22 measures temperature and humidity.
• MQ135 measures air quality (pollution level).
• Data is sent to ThingSpeak dashboard every 20 seconds.
• Municipal authorities or users can monitor the data in real-time.

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Advantages

• Real-time monitoring of city parameters
• Automation of street lighting, alerts, and environmental control
• Helps in energy conservation and pollution management
• Can scale for large urban areas

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Applications

• Smart city infrastructure management
• Environmental monitoring (air, temperature, humidity)
• Traffic control and smart street lighting
• Disaster management (flood detection, alarms)

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Future Enhancements

• Integrate traffic cameras and AI for vehicle analysis
• Add IoT-based waste monitoring
• Use solar-powered sensors for energy efficiency
• Combine multiple zones into a centralized smart city dashboard

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Conclusion

The Smart City Monitoring System is a comprehensive IoT project that demonstrates urban automation, environmental monitoring, and smart infrastructure management. It combines sensors, microcontrollers, and cloud platforms to make cities safer, smarter, and more energy-efficient.