int red = 13;
int yellow = 12;
int green = 8;

void setup() {
  pinMode(red, OUTPUT);
  pinMode(yellow, OUTPUT);
  pinMode(green, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  Serial.println("traffic Led");
  Serial.println("stop");
  digitalWrite(red, HIGH);
  delay(3000);
  digitalWrite(red, LOW);
  delay(3000);
  Serial.println("get ready");
  digitalWrite(yellow, HIGH);
  delay(3000);
  digitalWrite(yellow, LOW);
  delay(3000);
  Serial.println("go");
  digitalWrite(green, HIGH);
  delay(3000);
  digitalWrite(green, LOW);
  delay(3000);
}