I second what Trumpy said about the black UV stabilized cable ties. Another thought may be to wrap a couple of turns of self amalgamating rubber tape (of the type used for satellite connections outdoors) round the catenary at the points where there are ties. It's a little time consuming but it does prevent the ties from wearing through where they are in contact with the catenary, and it seems to hold up pretty well to weathering. I have known even slight movement to severely weaken the ties by sheer wear, if they have been exposed to high winds, even intermittently. I am wondering whether there is much ozone in the air there, as that can accelerate aging greatly.
