Automatic Railway Level Crossing Gate Controller using IR Sensors and Arduino

Level crossings remain one of the most accident-prone points on a railway network, and manually operated gates depend on a gateman noticing the train, reaching the gate in time, and closing it before road traffic enters the tracks. Human reaction time, fatigue, and unmanned crossings make this chain fragile. The engineering answer is automatic detection: sense the train's approach electronically, close the gate before it arrives, and reopen only after it has fully cleared. This project implements that exact loop at model scale — two reflective IR sensor modules watch the track on either side of the crossing, an Arduino UNO runs the detection and state-machine logic, an SG90 servo drives the gate arm, and red/green signal LEDs plus a buzzer warn road users. Because the prototype is built on a breadboard with visible wiring, every signal in the chain can be probed and explained.

1. Two reflective IR sensor modules are mounted on the model track, one on each approach side at a fixed distance from the crossing point, with detection distance set via each module's onboard potentiometer.
2. When a train body passes the arrival sensor, reflected IR crosses the module's comparator threshold and the Arduino registers an arrival event after a 200–500 ms debounce window (firmware-configurable).
3. The controller switches the signal LEDs to red, starts the buzzer, and drives the SG90 servo from 0° to 90°, lowering the gate arm to the horizontal closed position.
4. The gate stays closed while the departure-side sensor is untriggered — the firmware tracks crossing occupancy, not a single edge, so the gate cannot reopen under a slow or stopped train.
5. Once the train's tail clears the departure sensor, the controller waits a short clearance delay, then returns the servo to 0°, switches the signal to green, and silences the buzzer.
6. Arrival order (sensor 1 then 2, or the reverse) reveals the train's direction, but the safety logic is direction-agnostic: any confirmed arrival event closes the gate.

Tech stack:

• Arduino UNO (ATmega328P, 16 MHz)
• Embedded C · Arduino IDE
• Reflective IR sensor modules (LM358 comparator)
• SG90 micro servo motor
• 5 V buzzer · red/green signal LEDs
• Breadboard · jumper-wire prototyping
• Manual override push-button
• Regulated 5 V / 2 A power supply

• [Bidirectional train sensing] Two IR sensor modules mounted on either side of the crossing detect the train's arrival and departure independently, so the controller works for trains approaching from either direction.
• [Automatic servo gate arm] An SG90 servo rotates a red-and-white striped gate arm between the open (vertical) and closed (horizontal) positions with no human operator involved.
• [Red/green signal indication] 5 mm trackside LEDs mirror the gate state: red while the gate is closed or moving, green when the road is clear to cross.
• [Audible warning buzzer] A 5 V active buzzer sounds during gate movement and stays on while the crossing is occupied by the train.
• [Debounce and occupancy state machine] Firmware filters sensor bounce with a configurable debounce window and holds the gate closed until the departure sensor confirms the train has fully cleared — a slow or halted train keeps the gate down.
• [Manual override push-button] A panel button forces the gate open or closed for demonstrations or while a sensor is being serviced.
• [Adjustable gate timing] Open/close servo angles and the clearance delay before reopening are firmware constants, tuned during calibration for the student's own model track.

• Assembled working prototype (Arduino, IR sensors, servo gate, signal LEDs, buzzer on breadboard and plywood base)
• Arduino firmware source with comments and calibration constants
• Circuit wiring diagram and connection table
• Sensor sensitivity calibration guide with a buyer-run test procedure
• Project report PDF (background, sensor theory, methodology, results template)
• PPT presentation for final review
• Viva Q&A preparation document (IR sensing, servo control, state machines)

Delivery timeline

• Typical build-and-test time is 10–14 working days from order confirmation; the report, PPT and viva Q&A ship with the prototype. Exact dates are confirmed in the quotation.

Support & explanation

• Build walkthrough call covering sensor calibration and the firmware constants; viva preparation support on IR sensing, servo control and state-machine logic; 15 days of post-delivery query support.