Google direction time with traffic

I use google maps for my website, i want to get directions during traffic, how can i get estimated time during traffic in google maps directions ?

i use the following code to get directions without traffic.

function direction(){
    var directionsService = new google.maps.DirectionsService();
    var directionsRenderer = new google.maps.DirectionsRenderer();


    var nmap = new google.maps.Map(document.getElementById('direction-map'), mapOptions);
    directionsRenderer.setMap(nmap);

    calcRoute();
}

function calcRoute() {

    var blng = parseFloat($("#beginning-lng").val());
    var blat = parseFloat($("#beginning-lat").val());

    var dlng = parseFloat($("#destination-lng").val());
    var dlat = parseFloat($("#destination-lat").val());

    var start = new google.maps.LatLng(blat, blng);
    var end = new google.maps.LatLng(dlat, dlng);
    var request = {
        origin: start,
        destination: end,
        travelMode: 'DRIVING',
        avoidTolls: true
    };
    directionsService.route(request,  function (result, status) {
        if (status == 'OK') {
            directionsRenderer.setDirections(result);
            console.log(result);
            var distance = result.routes[0].legs[0].distance.value / 1000;
            var time = result.routes[0].legs[0].duration.value / 60;
        }
    });
}