sort of reminds me
Was at a ATT conference maybe 9 years ago. They had one bit where they talked about multiple provider network redundancy. Then they showed a slide of a (real)huge fiber cut that had probably a dozen or more carriers in the same pipe, I want to say the pipe or conduit was 1 to 2 feet wide buried in the ground.
Certainly was interesting to think about wrt datacenters and normal requirements that there be at least 2 fiber connection points on different sides of the building. How far might those fibers go before they converge? (If they converge) have never gotten a confident answer for that.