function time_sum() {
$i = 0;
foreach (func_get_args() as $time) {
sscanf($time, '%d:%d:%d', $hour, $min, $sec);
$i += ($hour * 360)+($min * 60)+$sec;
}
if ($h = floor($i / 360)) {
$i %= 360;
}
if ($m = floor($i / 60)) {
$i %= 60;
}
$s=$i;
return sprintf('%02d:%02d:%02d', $h, $m, $s);
}
echo time_sum('01:02:3', '01:2:3', '01:02:3');
//03:06:09