Automated Smart Bridge

The Automated Smart Bridge isn’t any normal bridge; it raises and lowers itself based off environmental conditions. When its sensors detects moisture, it displays a flood alert while simultaneously raising the bridge. The purpose of this bridge is to ensure that people can cross it safely during floody conditions.

Engineer	School	Area of Interest	Grade
Logan W	Irvine HS	Structural Engineering	Incoming Junior

Final Milestone

Modifications

• Created an E-STOP Button that stops the bridge from moving and returns the Bridge to its neutral position
• Created two soil moisture sensors to detect water in multiple places
• Added cardboard to the structure of the bridge to make it more secure
• Added a second servo to allow an extra arm to raise the bridge
• Added an 8V battery pack to power the second servo since the Arduino’s 5V can’t power both servos

Challenges I Overcame

• Breadboard overheated when I added the 8V battery pack for the second servo
• I unplugged all the wires and identified a dead short circuit casued by plugging the power wires of the servo into the ground rail
• I plugged my power wires into the positive rail and system functionaled normally again

Future Iterations

• I plan to finish the Github and Schematic

First Milestone

Different Components

• Soil Moisture Sensor: Detects moisture and sends signals to the Arduino when it detects low resistance (moist soil has low resistance compared to dry soil)
• Arduino: Acts as a motherboard and recieves signals from the Soil Moisture Sensor and sends signals to output components
• Servo: A motor that recieves signals from the Arduino and raises and lowers the bridge with its arm.
• OLED: A screen that recieves signals from the Ardunio and displays text
• Red LED: A light that recieves signals from the Arduino in Pin 6 and lights up when a flood is detected

Challenges I Overcame

• The physical wiring of the Arduino was the hardest part since I had to learn the basics of wiring it from scratch, now that I have finished the base project, I feel more confident about my wiring abilities
• It took trial and error, but the effort to connect the wires to the right places was incredibly rewarding once the bridge started working

Future Iterations

• I plan to make modifications to the bridge to improve safety

Schematics

Code

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Servo.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Define Pins
const int ESTOP_PIN = 2;     
const int SERVO1_PIN = 4;    
const int SENSOR1_PIN = 5;   
const int LED_PIN = 6;       
const int SERVO2_PIN = 7;    // Servo 2
const int SENSOR2_PIN = 8;   

Servo servo1;
Servo servo2;

bool estopTriggered = false; 
unsigned long lastFlashTime = 0;
bool ledState = LOW;

void setup() {
  Serial.begin(9600);
  
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(2);
  
  pinMode(SENSOR1_PIN, INPUT);
  pinMode(SENSOR2_PIN, INPUT);
  pinMode(LED_PIN, OUTPUT);     
  pinMode(ESTOP_PIN, INPUT_PULLUP); 
  
  servo1.attach(SERVO1_PIN);
  servo2.attach(SERVO2_PIN);
  
  // STARTING POSITIONS
  servo1.write(0);    // Servo 1 starts at 0
  servo2.write(90);   // Servo 2 starts at 90 (its "closed" position)
  digitalWrite(LED_PIN, LOW);   
}

void loop() {
  if (digitalRead(ESTOP_PIN) == LOW) {
    estopTriggered = true;
  }

  display.clearDisplay();
  display.setCursor(0, 0);
  
  if (estopTriggered) {
    display.println("EMERGENCY\nSTOP!!!");
    display.display();
    
    // Snap back to safe/closed positions
    servo1.write(0);
    servo2.write(90); 
    digitalWrite(LED_PIN, HIGH); 
    
    while(true) {}
  }

  int s1 = digitalRead(SENSOR1_PIN);
  int s2 = digitalRead(SENSOR2_PIN);
  
  if (s1 == LOW || s2 == LOW) {
    display.println("FLOOD\nALERT!");
    display.display();
    
    // OPEN THE GATES
    servo1.write(90);  // Servo 1 rotates up to 90
    servo2.write(0);   // Servo 2 rotates down to 0 (which mirrors it!)
    
    if (millis() - lastFlashTime >= 200) {
      lastFlashTime = millis();
      ledState = !ledState;
      digitalWrite(LED_PIN, ledState);
    }
  } 
  else {
    display.println("Safe\nLevel");
    display.display();
    
    // KEEP GATES CLOSED
    servo1.write(0);
    servo2.write(90);
    digitalWrite(LED_PIN, LOW);
  }
  
  delay(50); 
}

Bill of Materials

Part	Note	Price	Link
Arduino Uno	Recieves inputs from Moisture Sensor and sends signals to the outputs	$14.99	Link
OLED Module	Displays Text	$9.99	Link
Breadboard	Allows for multiple wires to share a GND and 5V connection	$7.89	Link
Micro Servo	Raises and lowers the bridge	$9.88	Link
Female Jumper Wires	Connects Moisture Sensor, OLED, and LED to the Arduino	$3.99	Link
Male Jumper Wires	Connects the Servo and Red Button to the Arduino	$3.99	Link
Soil Moisture Sensor	Detects Water	$12.99	Link
Red Button	E-Stops the Bridge	$8.99	Link
Red LED	Alarm	$5.99	Link
Cardboard	Structure of the Bridge	$24.99	Link
Construction Paper	Road	$5.38	Link
Battery Pack	Supplys Extra Power	$8.39	Link

Resources

Schematic Maker

Example Project

Code Maker

Arduino Programmer