If you come to a level crossing with a stop sign, but no stop line, you must stop completely just before entering the track area.
When you have a duty to stop, you must stop completely and give way. You should stop at the stop line or, as in this case, if there is no line, just before entering the track area.
Regardless of what type of safety device a level crossing is equipped with, you should never rely on it blindly – you must always check for approaching trains before passing the level crossing. Always look both left and right when checking.