🚦 Smart Adaptive Traffic Signal System (Arduino-Based)

📍 Project Overview

The Smart Adaptive Traffic Signal System is an Arduino-based prototype that intelligently controls traffic lights based on real-time traffic density and motion detection.
It minimizes waiting time, improves traffic flow efficiency, and safely handles emergency and pedestrian situations — making it a practical demonstration of smart city automation.

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🧠 Key Features

Feature	Description
Adaptive Timing	Automatically adjusts green light duration using an ultrasonic distance sensor.
Motion Detection	Detects vehicle movement on the secondary lane using a PIR sensor.
Emergency Mode	Instantly prioritizes one lane for emergency vehicles.
Pedestrian Mode	Halts all lanes temporarily for safe crossing with a buzzer alert.
Visual Display	LCD shows real-time status: lane, distance, activity, and timers.
Audible Alerts	Buzzer provides transition beeps and pedestrian countdown signals.

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🧩 Components Used

Component	Quantity	Function
Arduino UNO	1	Main controller
HC-SR04 Ultrasonic Sensor	1	Measures queue distance (Lane 1)
PIR Motion Sensor	1	Detects movement (Lane 2)
16x2 I²C LCD Display	1	Displays system status
LEDs (Red, Yellow, Green)	6	Simulate traffic lights
Push Buttons	2	Pedestrian and emergency triggers
Buzzer	1	Audible alerts
Breadboard, Jumpers, Resistors	—	Circuit wiring and support

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⚙️ Working Principle

1. Traffic Density Measurement

   • Ultrasonic sensor measures the distance of vehicles queued in Lane 1.
   • Shorter distance → higher density → longer green duration.

2. Motion Detection

   • PIR sensor detects approaching vehicles on Lane 2.
   • Detected motion increases green time for Lane 2.

3. Adaptive Control

   • Each lane’s green light duration adjusts dynamically:
     • High density → 7s
     • Medium → 5s
     • Low → 3s

4. Emergency Mode

   • Pressing the emergency button immediately activates green for Lane 1.

5. Pedestrian Mode

   • Pedestrian button activates an all-red state for 5 seconds with buzzer countdown.

6. Safety Transition

   • Includes 2-second yellow and 1-second all-red intervals to prevent collisions.

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🧾 Circuit Connection Table

Component	Arduino Pin	Description
HC-SR04 TRIG	D2	Ultrasonic trigger
HC-SR04 ECHO	D3	Ultrasonic echo
PIR OUT	D4	Motion input
Lane 1 LEDs	D5–D7	Green, Yellow, Red
Lane 2 LEDs	D8–D10	Green, Yellow, Red
Pedestrian Button	A0	Active LOW input
Emergency Button	A1	Active LOW input
Buzzer	A2	Tone output
LCD SDA	A4	I²C data
LCD SCL	A5	I²C clock
+5V / GND	—	Power to all modules

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🧱 Block Diagram

┌─────────────────────────────────┐
│           Arduino UNO           │
├─────────────────────────────────┤
│  HC-SR04 → D2 (TRIG), D3 (ECHO) │
│  PIR → D4                       │
│  LCD I²C → A4 (SDA), A5 (SCL)   │
│  Ped Btn → A0, Emerg Btn → A1   │
│  Buzzer → A2                    │
│  Lane 1 LEDs → D5–D7            │
│  Lane 2 LEDs → D8–D10           │
└─────────────────────────────────┘

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💻 Arduino Code

Full code is available in Smart_Traffic_Signal.ino

The code:

• Reads sensor inputs (HC-SR04, PIR)
• Calculates adaptive green times
• Displays results on LCD
• Handles pedestrian/emergency overrides
• Controls LEDs and buzzer alerts

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🔍 Verification & Testing

Test	Expected Behavior
Power ON	LCD shows “Smart Traffic System Ready.”
Ultrasonic Sensor	Move an object closer → Lane 1 green time increases.
PIR Sensor	Wave hand near PIR → Lane 2 activity increases.
Pedestrian Button	All lights turn red for 5 seconds; buzzer beeps.
Emergency Button	Lane 1 turns green immediately.
LCD Display	Shows lane status, sensor readings, and timers.

Use the Serial Monitor (115200 baud) to verify sensor data and timing logic.

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🧮 Timing Configuration

Traffic Condition	Lane 1 (Ultrasonic)	Lane 2 (PIR)
High Density	7 s Green	3–5 s Green
Medium Density	5 s Green	3–5 s Green
Low Density	3 s Green	3 s Green

Yellow phase → 2 s
All red → 0.8 s
Pedestrian crossing → 5 s

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🧠 Project Impact

• Technical Impact: Demonstrates adaptive embedded control using real-time sensor feedback.
• Social Impact: Reduces idle time, saves fuel, and improves pedestrian safety.
• Scalability: Can be expanded to 4-lane or IoT-connected traffic systems.

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🧰 Future Enhancements

• Add Wi-Fi (ESP8266) or GSM module for remote traffic monitoring.
• Integrate multiple ultrasonic sensors for 4-way intersections.
• Add data logging for traffic analytics.
• Use machine vision (camera module) for vehicle classification.

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👨‍💻 Project Details

• Hardware Platform: Arduino UNO R3
• Programming Language: C++ (Arduino IDE)
• Version: 1.0
• Project Type: Personal Academic Project
• Repository Purpose: For documentation and demonstration of embedded system design.

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⚖️ Personal Use Notice

This project is developed solely for personal and academic demonstration purposes.
You are free to view, study, and replicate this design for learning or non-commercial projects.
Please credit the author if you reference or reuse any part of the code or documentation.

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🚀 Smart traffic control today for smarter cities tomorrow.