function preloadStandardNav() {

    var imgRoot = "images/common/";

    journeys_on = new Image();
    journeys_on.src = imgRoot + "hdr_btn_journeys_on.jpg";
    journeys_off = new Image();
    journeys_off.src = imgRoot + "hdr_btn_journeys_off.jpg";

    timelines_on = new Image();
    timelines_on.src = imgRoot + "hdr_btn_timelines_on.jpg";
    timelines_off = new Image();
    timelines_off.src = imgRoot + "hdr_btn_timelines_off.jpg";
    
    people_on = new Image();
    people_on.src = imgRoot + "hdr_btn_people_on.jpg";
    people_off = new Image();
    people_off.src = imgRoot + "hdr_btn_people_off.jpg";
    
    about_on = new Image();
    about_on.src = imgRoot + "hdr_btn_about_on.jpg";
    about_off = new Image();
    about_off.src = imgRoot + "hdr_btn_about_off.jpg";
    
    discussions_on = new Image();
    discussions_on.src = imgRoot + "hdr_btn_discussions_on.jpg";
    discussions_off = new Image();
    discussions_off.src = imgRoot + "hdr_btn_discussions_off.jpg";
}

preloadStandardNav();