There were backup cables. The bridge carried 5 cables, redundancy configuration would have been 3+2 afaik. But only for purposes of maintenance, not to protect against hostile action. For that, one should have taken care to not have all redundancies on the same bridge ;)

And in most environments, you cannot hide the location of those cables. Either they are visible directly, like all overhead power lines. No use in hiding those. And for the underground ones, you could try to hide them. But every backhoe operator will rightfully want a map of those anyways, so the information will come out in some way.

The only environment where hiding this kind of infrastructure would be possible is some state-does-everything soviet-like police state. Where comrade backhoe-operator wouldn't get a map, but he would get accompanied by a secret police supervisor who would tell him where to dig and where not to.