Add Google Transit layer to Google Maps API

gistfile1.js

var transitOptions = {
  getTileUrl: function(coord, zoom) {
    return "http://mt1.google.com/vt/lyrs=m@155076273,transit:comp|vm:&" +
    "hl=en&opts=r&s=Galil&z=" + zoom + "&x=" + coord.x + "&y=" + coord.y;
  },
  tileSize: new google.maps.Size(256, 256),
  isPng: true
};

var transitMapType = new google.maps.ImageMapType(transitOptions);

map.overlayMapTypes.insertAt(0, transitMapType);