function swapon(objname,imgobj) {

  document[objname].src=imgobj.src;
}

function swapoff(objname, imgpage) {
  document[objname].src = imgpage;
}

var roads_on = new Image(); roads_on.src = '/images/hdr_routes_on.gif';
var destinations_on = new Image(); destinations_on.src = '/images/hdr_destinations_on.gif';
var events_on = new Image(); events_on.src = '/images/hdr_events_on.gif';
var article_on = new Image(); article_on.src = '/images/hdr_articles_on.gif';
var forum_on = new Image(); forum_on.src = '/images/hdr_forum_on.gif';