Grade Crossing Flasher

// Grade Crossing Flasher
const int IR_SENSOR = 2;
const int LED1 = 3;
const int LED2 = 4;
const int FLASH_DELAY = 500;

void setup() {
  pinMode(IR_SENSOR, INPUT);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
}

void loop() {
  if (digitalRead(IR_SENSOR) == LOW) { // Train detected
    digitalWrite(LED1, HIGH);
    digitalWrite(LED2, LOW);
    delay(FLASH_DELAY);
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, HIGH);
    delay(FLASH_DELAY);
  } else {
    digitalWrite(LED1, LOW);
    digitalWrite(LED2, LOW);
  }
}