How to add more points to Google Directions route?

Question

I managed to add two points to Google Directions route - start and end point, but I'm interested to adding more end points like on this site: http://www.bikeroutetoaster.com/Course.aspx

When user adds third point, the route is continuing, but waypoint on second point stays. This is my code:

 function addRoute(event) {
        if(markers.length < 2){
            var marker = new google.maps.Marker({
                position: event.latLng,
                map: map,
                draggable: true
            });
            markers.push(marker);
        }

        if(markers.length == 2){
            var start = markers[0].getPosition();
            var end = markers[1].getPosition();

            putDirections(start, end);

            $(markers).each(function(i, marker){
                google.maps.event.addListener(marker, 'dragend', function(){
                    clearDirections();
                    var start = markers[0].getPosition();
                    var end = markers[1].getPosition();
                    putDirections(start, end);
                });
            });
        }


    }