I actually got to see one of those once.

For a major trans-oceanic backbone provider, at least 15ish years ago they had a mile or two between Detroit and Chicago where both ends were on the same side of the interstate highway.

But it's more frequent on DAS (Distributed Antenna Systems, AKA small-cell or micro-cell) networks.

Also the challenge of when fibers are leased (if that's still a thing, based on the networks I helped design I'd say 'probably').

They really are analogous to Lamport's "Distributed System" quip; A damaged fiber owned by a company you have never heard of can wreck your day.

>Sometimes your multiple fiber paths end up in the same bundle

For mission critical stuff like airports I would like to think they're go for a more rigorous methodology than hope for the best on paths

Years ago I was touring a POP in a small city. They were very proud to point out one fiber coming in one side of the building going South and another on the opposite side of the building going North.

last time this happened in my area a local farmer was burying a cow and took out the whole towns connection

Put all your backups in one basket, and then pray that nobody crushes the basket.

That is negligence, practical if not contractual.

Over ten years ago, my employer was spinning up a new DC across the state and had three links between it and the primary DC. Two were pretty direct, but we needed a third because at one point in the 300 mile path, the two main links went within 400 meters of each other.

So how national-security-adjacent critical systems like an airport system doesn't have a larger set of backup links, and validates that they are geographically separate up until the connections, and have realtime alerting on the connection status, is surprising to me.