#define RED 1
#define YELLOW 5
#define GREEN 9
#define RED2 10
#define YELLOW2 11
#define GREEN2 12
#define TRIG1 2
#define ECHO1 3
#define TRIG2 19
#define ECHO2 18

long duration1, distance1;
long duration2, distance2;

void setup() {
  pinMode(RED, OUTPUT);
  pinMode(YELLOW, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(RED2, OUTPUT);
  pinMode(YELLOW2, OUTPUT);
  pinMode(GREEN2, OUTPUT);
  pinMode(TRIG1, OUTPUT);
  pinMode(ECHO1, INPUT);
  pinMode(TRIG2, OUTPUT);
  pinMode(ECHO2, INPUT);
  Serial.begin(9600);
}

void loop() {
  // Measure distance for road 1
  digitalWrite(TRIG1, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG1, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG1, LOW);
  duration1 = pulseIn(ECHO1, HIGH);
  distance1 = duration1 * 0.034 / 2;

  // Measure distance for road 2
  digitalWrite(TRIG2, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG2, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG2, LOW);
  duration2 = pulseIn(ECHO2, HIGH);
  distance2 = duration2 * 0.034 / 2;

  // Check which road has more traffic
  if (distance1 < 31) {
    // Clear traffic for road 1 first
    clearTraffic(GREEN, YELLOW, RED);
  } else if (distance2 < 31) {
    // Clear traffic for road 2 first
    clearTraffic(GREEN2, YELLOW2, RED2);
  } else {
    // Normal traffic rule
    clearTraffic(GREEN, YELLOW, RED);
    clearTraffic(GREEN2, YELLOW2, RED2);
  }
}

void clearTraffic(int greenPin, int yellowPin, int redPin) {
  digitalWrite(greenPin, HIGH);
  digitalWrite(redPin, LOW);
  delay(3000);

  digitalWrite(greenPin, LOW);
  digitalWrite(yellowPin, HIGH);
  delay(500);

  digitalWrite(yellowPin, LOW);
  digitalWrite(redPin, HIGH);
  delay(2000);

  digitalWrite(yellowPin, HIGH);
  delay(500);
  digitalWrite(yellowPin, LOW);
  digitalWrite(redPin, LOW);
}