void setup()
{
  Serial.begin(9600);
  pinMode(2,OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(4,OUTPUT);
}

void loop()
{
  digitalWrite(2,HIGH);
  digitalWrite(3,LOW);
  digitalWrite(4,LOW);
  Serial.println("Red Light-Stop!");
  delay(15000);

  digitalWrite(2,LOW);
  digitalWrite(3,HIGH);
  digitalWrite(4,LOW);
  Serial.println("Yellow Light-Prepare!");
  delay(15000);

  digitalWrite(2,LOW);
  digitalWrite(3,LOW);
  digitalWrite(4,HIGH);
  Serial.println("Green Light-Go!");
  delay(15000);
}