[CedarDave]

Usually you build the supporting elements (the suspension tower, in this case) FIRST.

I followed the construction of the new Tilikum Crossing bridge in Portland, OR. They did exactly that with the tower first and then cables put in place as each section advanced toward the center. At completion the cables received final tensioning.

[ProtectOurFreedom]

It's been done that way for quite a while.