[рони]

Irina_hines,
а так?

function calcRoute2() {
    var start = calcRoute();
    $.ajax({
        type: "POST",
        url: "index.php",
        dataType: "text",
        data: "param=" + calcRoute(),
        success: function(data) {
            var request = {
                origin: start,
                destination: data,
                travelMode: google.maps.TravelMode.DRIVING
            };
            directionsService.route(request, function(response, status) {
                if (status == google.maps.DirectionsStatus.OK) directionsDisplay.setDirections(response)
            })
        }
    })
};