Railroad Crossing Lights

/*
 Railroad crossing lights
by DAVID
 */
// constants won't change. Used here to set a pin number :
const int ledPinP1 =  9;     // the number of the LED pin
const int ledPinP2 =  6;     // the number of the LED pin
const int ledPinF =  3;     // the number of the LED pin
const int switchPin = 2;    // the number of the switch pin
int switchState = 0;       // variable for reading the switch status   

void setup() {
  
  pinMode(ledPinP1, OUTPUT);  // initialize the LED pin as an output:
  pinMode(ledPinP2, OUTPUT);
  pinMode(ledPinF, OUTPUT);
  pinMode(switchPin, INPUT);  // initialize the pushbutton pin as an input:
}

void loop() 
{
    switchState = digitalRead(switchPin);   // read the state of the 
                                            //pushbuttonvalue:
    if (switchState == HIGH)   //if the switch on:
    {
        digitalWrite(ledPinF, LOW);     //white LED off
        digitalWrite(ledPinP1, HIGH);   //red1 LED on
        digitalWrite(ledPinP2, LOW);    //red2 LED off
        delay(400);                     //wait 400ms
        digitalWrite(ledPinP1, LOW);    //red1 LED off
        digitalWrite(ledPinP2, HIGH);   //red2 LED on
        delay(400);
    }
    if(switchState == LOW)              //if the switch off
    {
        digitalWrite(ledPinP1, LOW);    //red1 LED off
        digitalWrite(ledPinP2, LOW);    //red2 LED off
        digitalWrite(ledPinF, HIGH);    //white LED on
        delay(500);                     //wait 500ms
        digitalWrite(ledPinF, LOW);     //white LED off
        delay(500);
    }
}