Uzin, you say that it is not a normal il2 bridge but rather a bridge assembled with bridge segments from the objects menu?
Why not using the normal il2 bridges, you are above zero level altitude? You'll have good visibility range by default. With objects from objects menu visibilty is controlled by several files (.mat and especially .msh files) in several files+ some hardcode. Is also what you show in the actors.static or objects are set in a mission file?
If it's actors.static, do following: place a plate (say invisible) close to the start of the bridge. save new actors.static and if you go and play visibility should be given by the numbers in the bridge .msh, usually tose are anyway set to about 10000 meter (that is because there's some hardcode which limits objects visibility to 3000 meters if these objects are from objects menu. However placing a plate close to object in the map's actors.static restores the visibility given by the msh and mat files).To change the pop-up distance of objects you need to get a prog to open the .msh files and convert to readable, there you can change pop-up distance...
Sorry for the bad explanations etc, not much time..