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I have read that the pylon and cable stays were “aesthetic” and not structural...

I find that hard to believe. That's a long, heavy span. And, it's got no structural steel in it. All strength is provided by squeezing the concrete via tensioned cables (which apparently they found weren't tensioned enough, which is why they were doing the "test" when it collapsed).

As an analogy, consider a roll of coins. If oriented vertically, they can support a ton or more. If oriented horizontally, they fall apart. However, if you squeeze the coins while you hold them horizontal, they can take some transverse vertical load. That's what was supposed to be going on here.

But, again, looking at the bridge span, there was a rather heavily trussed structure that was going to accept the cable stays, which make sense. But the span platform itself was very thin. That just don't look right to me.

Good post. Those were my conclusions when I first reviewed the photos.

I think the "test" claim had more to do with the post tension work. We are missing photos of the other side. One. I wonder if there was a pull out of the tensioners on the other side during the "test?" Two. Did they fail to adequately tension the span before placement?

The design and project schedule still troubles me. Safety is an afterthought now.

However, if you squeeze the coins while you hold them horizontal, they can take some transverse vertical load. That's what was supposed to be going on here.

That doesn't sound like a design premise that I'd feel comfortable with.