Linear cable engine - GIF

[hemmjo]

They are moving that cable from over there to over here. Ha, just kidding.

That structure just looks like a BIG cable tray, like like you might find hidden in the ceilings of many buildings. Cable has limits in regard to how much tension you can use when pulling them. This is especially critical with fiber optic cable. It is possible that big cable contains thousands of fiber optic strands. If you are making a long pull, if you only pull from the end, it is easy to exceed the that maximum limit.

While I do not know for sure, I am guessing that is an intermediate pulling station. It would allow pulling a longer cable without exceeding the maximum tension limit.

That is my guess.