North American Network Operators Group

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How to repair fiber cuts...

  • From: Alex Bligh
  • Date: Sat Mar 14 07:02:14 1998

Being a European, I was wondering if some enlightened US person
could give me some operational info on how fiber cuts are repaired
in the US.

Specifically what I am interested in those caused by train derailments.
As I understand it in the US a lot of fiber runs alongside tracks,
or is buried not very deep. Presumably when a train is derailed,
it can be going at a reasonable speed, and is likely to (a) shred
a few hundred meters of fiber, and (b) possibly fall on top of it making
it difficult to physically access. Also one presumes that the affected
area is then covered in cranes, winches, emergency services etc. who
are likely to cause more damage.

I am therefore presuming that what happens is someone splices around the
cut with a (reasonably long) piece of fiber that they keep for this
sort of eventuality, and later when things have calmed down the fiber
is respliced to go along its original path. Is this correct?

1. How long after such a disastrous cut occurs is it normal to have
   connectivity back?
2. Do operators in general keep spare fiber? If so, how do they get it
   there? By road or by rail (both might be difficult)?
3. How long does the splicing operation itself take?
4. Can the resplice in general be done without much service interruption?

It's (1) I'm most interested in - is the cut normally repaired (for
instance) within 24 hours?

In case you were wondering, the reason I'm asking this is because I have
a theory I want to check out, which is that being spoilt with SDH over
here, the operators have less (or indeed no) proper disaster plan for
fiber cuts (varies operator to operator), and thus they get really
caught out either when there are two cuts, when their SDH doesn't do
the right thing, or when they forget that certain things aren't SDH.
(Yes Peter, you know who I mean).

Alex Bligh
GX Networks (formerly Xara Networks)