After cable is broken, approximate location is given by reflectometers at both ends.
Then, team arrive at this location and use special cable search tool to locate fault
Many tools is locally made, in Russia
It turned out that fault location is under water, here they use mobile pump, to dry the location
Together with pump, rostelecom has special small excavators
Cable is broken in multiple places, they should replace approx 10m of backbone cable
Fiber welding, as it is delicate matter is done in special vehicle. Here is important note, when someone show you they do welding under open air, this means probably they will get screwed up optical budget at the end, and whole project will be very unreliable.
Here is how it is done right:
This car is specially customized to work with fiber optics, you can see two holes, where cable pulled, but when it is done, you can open it completely, and remove cable.
Place should be relatively clean: