function onewayTrip(){
    var fsp = document.afpForm;
    fsp.retm.disabled = true;
    fsp.retd.disabled = true;
    fsp.reth.disabled = true;
    tripType = "O";
}
function returnTrip(){
    var fsp = document.afpForm;
    fsp.retm.disabled = false;
    fsp.retd.disabled = false;
    fsp.reth.disabled = false;
    tripType = "R";
}