An analogy of Bridges

  Have you noticed that, when a free-standing bridge is being built across a canyon (or span of water, whatever,) they start with building a solid anchor on each side, then run very strong cables across the chasm before they start building in the space between? It definitely wouldn't be advisable to try to build from one side of the space, only. The weight of the finished part would definitely bring it down before it spanned the two anchors.

My analogy requires a base to be built on the opposite end...someone who can pull hard and sustain a lot of weight. I'll do my end of the work, but I can't do both ends.  Any volunteers to start building an anchor at the far end of our span?
Troubled waters, down below?...(think about it?  ...at least, there's a chance of survival after a fall...)
Or:  If our chasm is dry, one's most unpleasant death would be a certainty...
We can do so much better!!!