tracking fiber assets

What do people use to keep track of fiber-optic assets? We own fiber on
electric transmission lines - a hundred spans or so, mostly 24-48 count,
about 800-900 total route-miles. But we lack a tool to keep track of
what is in use, which customers would be affected when we perform
maintenance, and the like.

Any suggestions for good tools to manage this would be most appreciated.
Our spreadsheets, CAD drawings, and directories full of OTDR shots are
just not cutting it.