level crossing 3 track annotated in model

/*level crossing 3 track 2may update
  This code is an adaptation of the originalcode written by Ruud Boer.  The orginal can be obtained by visiting his site
  at https://rudysarduinoprojects.wordpress.com/2019/03/10/fun-with-arduino-20-railway-crossing-part-4-putting-it-all-together/
  The changes to that code, done by Gary Granai, https://steamtraininfo.com/admin/home/arduino-projects, consist of changing pin
  definitions, adding connections for a third track and defining pin numbers to make wiring the circuit board
  easier. Explanitory comments have also been added.
  This adapted sketch is copywrite Gary Granai and you are free to use it and make changes as long as these credits
  remain intact and unchanged.
*/
#define GATE_SPEED          30 // [ms] lower number is higher servo speed
#define BLINK_SPEED         400 // [ms] smaller number is faster blinking
#define GATE_DELAY         1500 // [ms] time between start blinking and gate closing
#define END_OF_TRAIN_DELAY 2000 // [ms] time to wait before deciding this was the end of the train
#define GATE_OPEN_ANGLE_1    90 //change as you wish
#define GATE_CLOSED_ANGLE_1  10 //change as you wish
#define GATE_OPEN_ANGLE_2    90  //change as you wish
#define GATE_CLOSED_ANGLE_2  10 //change as you wish
#define SERVO1_PIN           10 /*a pwm pin.  Two externally powered servos are controlled by this pin. These servos
are on the road entrance side of the track. They move first when a train enters the protected area and second when
the crossing is clear of trains,*/
#define SERVO2_PIN           11 /*a pwm pin.  Two externally powered servos are controlled by this pin. These servos
are on the road exit side of the track. They move second when a train enters the protected area and first when
the crossing is clear of trains,*/
#define LED1_PIN              8 //one of the flashing lights.
#define LED2_PIN              9  //the second flashing light.
#define NUM_SENSORS           6 // two sensors per track, one left and one right of the gate
byte sensor_pin[NUM_SENSORS]  = {2, 3, 4, 5, 6, 7}; // sensor "OUT" wires connect to these pins.

//leave eerything below as it is.
byte state = 1;
byte train_counter, n;
byte led1, led2, blink_enabled;
byte    angle1 = GATE_OPEN_ANGLE_1;
byte setpoint1 = GATE_OPEN_ANGLE_1;
byte    angle2 = GATE_OPEN_ANGLE_2;
byte setpoint2 = GATE_OPEN_ANGLE_2;
byte sensor_state[NUM_SENSORS]; // 0 idle, 1 detect arrival, 2 detect departure, 3 detect end of train
byte end_of_train[NUM_SENSORS]; // 0 idle, 1 end of train detected
unsigned long time_to_blink;
unsigned long time_to_close_gate;
unsigned long time_for_servo_step;
unsigned long time_end_of_train[NUM_SENSORS];

#include <Servo.h>
Servo gate_servo1;
Servo gate_servo2;

void setup() {
  pinMode(LED1_PIN, OUTPUT);
  pinMode(LED2_PIN, OUTPUT);
  for (byte i = 0; i < NUM_SENSORS; i++) pinMode(sensor_pin[i], INPUT_PULLUP);
  gate_servo1.attach(SERVO1_PIN);
  gate_servo1.write(angle1);
  gate_servo2.attach(SERVO2_PIN);
  gate_servo2.write(angle2);
  delay(1000);
  gate_servo1.detach();
  gate_servo2.detach();
  Serial.begin(9600);
  Serial.println("Railway Crossing Control Ready");
  Serial.println();
  Serial.println("Waiting for train");
  for (byte i = 0; i < NUM_SENSORS; i++) sensor_state[i] = 1; // enable sensors for train detection
}

void loop() {

  for (byte i = 0; i < NUM_SENSORS; i++) {
    if (sensor_state[i] == 1) { // detect arrival of new train
      if (!digitalRead(sensor_pin[i])) { // train detected
        train_counter++;
        sensor_state[i] = 0;
        if (i % 2) n = i - 1; else n = i + 1;
        sensor_state[n] = 2; // buddy sensor departure detection enabled
        Serial.print("Arrival:   ");
        Serial.println(i);
        Serial.print("Trains:    ");
        Serial.println(train_counter);
      }
    }
    else if (sensor_state[i] > 1) {
      if (!digitalRead(sensor_pin[i])) { // departure detected
        time_end_of_train[i] = millis() + (unsigned long)END_OF_TRAIN_DELAY;
        if (i % 2) n = i - 1; else n = i + 1;
        sensor_state[n] = 1; // buddy sensor enabled again
        if (sensor_state[i] == 2) {
          Serial.print("Departure: ");
          Serial.println(i);
        }
        sensor_state[i] = 3;
      }
      if (sensor_state[i] == 3) // decide if end of train has passed based on a timer
        if (millis() > time_end_of_train[i]) end_of_train[i] = 1;
      if (end_of_train[i]) { // this takes care train_counter-- is executed only once
        train_counter--;
        end_of_train[i] = 0;
        sensor_state[i] = 1;
        Serial.print("Trains:    ");
        Serial.println(train_counter);
      }
    }
  }

  switch (state) {
    case 1: // Gates open. Not blinking. Waiting for train.
      if (train_counter) { // A train is detected.
        Serial.println("Binking started");
        blink_enabled = 1;
        time_to_close_gate = millis() + (unsigned long)GATE_DELAY;
        state = 2;
      }
      break;

    case 2: // Blinking. Wait until it's time to close the gates
      if (millis() > time_to_close_gate) { // Gate delay time has passed
        Serial.println("Gate1 closing");
        gate_servo1.attach(SERVO1_PIN);
        setpoint1 = GATE_CLOSED_ANGLE_1;
        state = 3;
      }
      break;

    case 3: // Gate1 closing. Blinking.
      if (angle1 == setpoint1) { // Gate1 closed
        gate_servo1.detach();
        Serial.println("Gate1 closed");
        Serial.println("Gate2 closing");
        gate_servo2.attach(SERVO2_PIN);
        setpoint2 = GATE_CLOSED_ANGLE_2;
        state = 4;
      }
      break;

    case 4: // Gate2 closing. Blinking.
      if (angle2 == setpoint2) { // Gate2 is fully closed
        gate_servo2.detach();
        Serial.println("Gate2 closed");
        state = 5;
      }
      break;

    case 5: // Gate2 closed. Blinking. Wait until all trains are gone.
      if (!train_counter) { // End of last train detected
        Serial.println("Gate2 opening");
        gate_servo2.attach(SERVO2_PIN);
        setpoint2 = GATE_OPEN_ANGLE_2;
        state = 6;
      }
      break;

    case 6: // Gate2 opening. Blinking.
      if (train_counter) state = 3; // Another train is coming
      else if (angle2 == setpoint2) { // Gate2 open
        gate_servo2.detach();
        Serial.println("Gate2 open");
        Serial.println("Gate1 opening");
        gate_servo1.attach(SERVO1_PIN);
        setpoint1 = GATE_OPEN_ANGLE_1;
        state = 7;
      }
      break;

    case 7: // Gate1 opening. Blinking.
      if (train_counter) state = 2; // Another train is coming
      else if (angle1 == setpoint1) { // Gate1 open
        gate_servo1.detach();
        Serial.println("Gate1 open");
        Serial.println("Stop blinking");
        blink_enabled = 0; // Stop blinking
        led1 = 0;
        led2 = 0;
        Serial.println();
        Serial.println("Waiting for train");
        state = 1;
      }
      break;
  }

  if (millis() > time_for_servo_step) {
    time_for_servo_step = millis() + (unsigned long)GATE_SPEED;
    if (angle1 < setpoint1) angle1++;
    if (angle1 > setpoint1) angle1--;
    if (angle2 < setpoint2) angle2++;
    if (angle2 > setpoint2) angle2--;
    gate_servo1.write(angle1);
    gate_servo2.write(angle2);
  }

  if (blink_enabled == 1) {
    if (millis() > time_to_blink) {
      time_to_blink = millis() + (unsigned long)BLINK_SPEED;
      led1 = !led1;
      led2 = !led1;
    }
  }

  digitalWrite(LED1_PIN, led1);
  digitalWrite(LED2_PIN, led2);
}