int signal1[] = {13,12,15};
int signal2[] = {16,17,5};
int signal3[] = {18,19,21};
int signal4[] = {4,3,2};

void setup(){
 for (int i = 0; i < 3; i++) {
    pinMode(signal1[i], OUTPUT);
    pinMode(signal2[i], OUTPUT);
    pinMode(signal3[i], OUTPUT);
    pinMode(signal4[i], OUTPUT);
 } 
}
void loop(){
  int redDelay= 8000;
  int yellowDelay= 20;
  digitalWrite(signal1[2], HIGH);
  digitalWrite(signal1[0], LOW);
  digitalWrite(signal2[0], HIGH);
  digitalWrite(signal3[0], HIGH);
  digitalWrite(signal4[0], HIGH);
  delay(redDelay);
  digitalWrite(signal1[1], HIGH);
  digitalWrite(signal1[2], LOW);
  delay(yellowDelay);
  digitalWrite(signal1[1], LOW);
  digitalWrite(signal1[0], HIGH);
  digitalWrite(signal2[2], HIGH);
  digitalWrite(signal2[0], LOW);
  digitalWrite(signal3[0], HIGH);
  digitalWrite(signal4[0], HIGH);
  delay(redDelay);
  digitalWrite(signal2[1], HIGH);
  digitalWrite(signal2[2], LOW);
  delay(yellowDelay);
  digitalWrite(signal2[1], LOW);
   digitalWrite(signal1[0], HIGH);
  digitalWrite(signal2[0], HIGH);
  digitalWrite(signal3[2], HIGH);
  digitalWrite(signal3[0], LOW);
  digitalWrite(signal4[0], HIGH);
  delay(redDelay);
   digitalWrite(signal3[1], HIGH);
  digitalWrite(signal3[2], LOW);
  delay(yellowDelay);
  digitalWrite(signal3[1], LOW);
   digitalWrite(signal1[0], HIGH);
  digitalWrite(signal2[0], HIGH);
  digitalWrite(signal3[0], HIGH);
  digitalWrite(signal4[2], HIGH);
  digitalWrite(signal4[0], LOW);
  delay(redDelay);
   digitalWrite(signal4[0], HIGH);
  digitalWrite(signal4[0], LOW);
  delay(yellowDelay);
  digitalWrite(signal4[0], LOW);
}