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";

    nav_bot_about_on = new Image();
    nav_bot_about_on.src = imgRoot + "btn_about_the_series_on.gif";
    nav_bot_about_off = new Image();
    nav_bot_about_off.src = imgRoot + "btn_about_the_series_off.gif";

    nav_bot_discussions_on = new Image();
    nav_bot_discussions_on.src = imgRoot + "btn_discussions_on.gif";
    nav_bot_discussions_off = new Image();
    nav_bot_discussions_off.src = imgRoot + "btn_discussions_off.gif";

    nav_bot_journeys_on = new Image();
    nav_bot_journeys_on.src = imgRoot + "btn_journeys_on.gif";
    nav_bot_journeys_off = new Image();
    nav_bot_journeys_off.src = imgRoot + "btn_journeys_off.gif";

    nav_bot_timeline_on = new Image();
    nav_bot_timeline_on.src = imgRoot + "btn_timeline_on.gif";
    nav_bot_timeline_off = new Image();
    nav_bot_timeline_off.src = imgRoot + "btn_timeline_off.gif";

    nav_bot_people_on = new Image();
    nav_bot_people_on.src = imgRoot + "btn_people_on.gif";
    nav_bot_people_off = new Image();
    nav_bot_people_off.src = imgRoot + "btn_people_off.gif";

    nav_bot_site_map_on = new Image();
    nav_bot_site_map_on.src = imgRoot + "btn_site_map_on.gif";
    nav_bot_site_map_off = new Image();
    nav_bot_site_map_off.src = imgRoot + "btn_site_map_off.gif";

    nav_bot_privacy_policy_on = new Image();
    nav_bot_privacy_policy_on.src = imgRoot + "btn_privacy_policy_on.gif";
    nav_bot_privacy_policy_off = new Image();
    nav_bot_privacy_policy_off.src = imgRoot + "btn_privacy_policy_off.gif";

    nav_bot_site_credits_on = new Image();
    nav_bot_site_credits_on.src = imgRoot + "btn_site_credits_on.gif";
    nav_bot_site_credits_off = new Image();
    nav_bot_site_credits_off.src = imgRoot + "btn_site_credits_off.gif";

    nav_bot_resources_on = new Image();
    nav_bot_resources_on.src = imgRoot + "btn_resources_on.gif";
    nav_bot_resources_off = new Image();
    nav_bot_resources_off.src = imgRoot + "btn_resources_off.gif";

}

preloadStandardNav();