Transarctia AI train movement

/**** AI movement action (every 60 ms) ****/

    $AIMoveTrainInterval = window.setInterval(function() {

        // If the AI is active
        if($aiToggle == true) {

            // If the AI engine has not been destroyed
            if(!$aiTrain.find(".engine").hasClass("destroyed")) {

                // If the AI train has not reached the right end of the scene (Collision detection)
                if(parseInt($aiTrain.css("left")) + $aiTrain.width() < $("#scene").width() && $AIMoveTrainDirection == 'right') {

                    // Move the AI train to the right
                    $aiTrain.css("left",parseInt($aiTrain.css("left"))+2);
                }

                // If the AI train has not reached the left end of the scene (Collision detection)
                if(parseInt($aiTrain.css("left")) > 1 && $AIMoveTrainDirection == 'left') {

                    // Move the AI train to the left
                    $aiTrain.css("left",parseInt($aiTrain.css("left"))-2);
                }
            }
        }
    },60);

    // Interval for random moving direction for the AI
    $AIMoveDecisionInterval = window.setInterval(function() {

        // Pick a random direction
        var $AIRandomDirection = Math.floor(Math.random() * $AIMoveTrainDecisions.length);

        // If the player train moves
        if($movePlayerTrainInterval != null) {

            // If the AI train does not move in the same direction as the player train
            if($AIMoveTrainDirection != $movePlayerTrainDirection) {

                // There is a 10% chance that the AI train WILL NOT move in the same direction as the player train
                $AIMoveTrainDirection = $(this).rand(0,100) < 10 ? $AIMoveTrainDecisions[$AIRandomDirection] : $movePlayerTrainDirection;

            // If the player train moves
            } else {

                // There is 80% chance that the AI train WILL NOT pick a random direction
                $AIMoveTrainDirection = $(this).rand(0,100) > 80 ? $AIMoveTrainDecisions[$AIRandomDirection] : $movePlayerTrainDirection;
            }

        } else {

            // If the AI Train does not move
            if($AIMoveTrainDirection == 'undefined') {
                $AIMoveTrainDirection = $AIMoveTrainDecisions[$AIRandomDirection];
            } else {

                // Pick a random Number
                var $random = $(this).rand(0,100);

                // If the AI train moves to the left, there is a 90% chance that the AI train will continue moving left
                $AIMoveTrainDirection = $AIMoveTrainDirection == 'left' && $random <= 90 ? 'left' : $AIMoveTrainDecisions[$AIRandomDirection];

                // If the AI train moves to the right, there is a 90% chance that the AI train will continue moving right
                $AIMoveTrainDirection = $AIMoveTrainDirection == 'right' && $random <= 90 ? 'right' : $AIMoveTrainDecisions[$AIRandomDirection];

                // IF the AI train has stopped, there is a 20% chance that the AI train will stay still
                $AIMoveTrainDirection = $AIMoveTrainDirection == 'stop' && $random <= 20 ? 'stop' : $AIMoveTrainDecisions[$AIRandomDirection];
            }
        }

    },$AIMoveTrainDirection == 'undefined' ? 500 : 5000);