// This program is to simulate Traffic Signals.

void setup()
{
pinMode(13,OUTPUT);   // Red LED
pinMode(12,OUTPUT);   // Yellow LED
pinMode(11,OUTPUT);   // Green LED
pinMode(10,OUTPUT);   // Red LED
pinMode(9,OUTPUT);    // Yellow LED
pinMode(8,OUTPUT);    // Green LED
}

void loop()
{
digitalWrite(13, HIGH); // Phase 1.
digitalWrite(8, HIGH);
delay(2000);

digitalWrite(8, LOW);   // Phase 2.
digitalWrite(9, HIGH);
delay(1000);

digitalWrite(9, LOW);   // Phase 3.
digitalWrite(10, HIGH);
delay(1000);

digitalWrite(13, LOW);  // Phase 4.
digitalWrite(11, HIGH);
delay(3000);

digitalWrite(11, LOW);   // Phase 5.
digitalWrite(12, HIGH);
delay(1000);

digitalWrite(12, LOW);  // Phase 6.
digitalWrite(13, HIGH);
delay(1000);

digitalWrite(10, LOW);  // Phase 7. 
digitalWrite(8, HIGH);
delay(100);
}