title: Can the Google traffic layer be added to an OpenLayers 2 map without displaying a Google base map
body: <p>I know I can add a Google map to an OpenLayers 2 map as an OpenLayers.Layer.Google(.v3) layer and can add the traffic layer to the included map using code like:</p>
  
  <pre><code>var map;
  
  function init() {
      map = new OpenLayers.Map('map');
      map.addControl(new OpenLayers.Control.LayerSwitcher());
  
      var gphy = new OpenLayers.Layer.Google(
          "Google Physical",
          {type: google.maps.MapTypeId.TERRAIN}
      );
      var gmap = new OpenLayers.Layer.Google(
          "Google Streets", // the default
          {numZoomLevels: 20}
      );
  
      map.addLayers([gmap, gphy]);
  
      var trafficLayer = new google.maps.TrafficLayer();
      trafficLayer.setMap(gmap.mapObject);
  
      map.setCenter(new OpenLayers.LonLat(-2, 50.9).transform(
          new OpenLayers.Projection("EPSG:4326"),
          map.getProjectionObject()
      ), 10);
  
  }
  </code></pre>
  
  <p>However our site uses a set of standard base maps and we would like to be able to display the traffic layer over these. Is this possible?</p>
  
  <p>We would also be interested in being able to display Google weather and the Streetview overlay in a similar fashion. </p>
  
  <p>Our site already uses Spherical Mercator projection so this is not an issue.</p>