[Alberta's Child]

The design seems sound from my very distant viewpoint. They used a cable-stayed design so the bridge could have a long continuous span over the roadway without a column in the middle of the road.

The construction process here seems highly questionable.

If the bridge section failed at one end, then it was probably a shear failure. For a structure like that one, the maximum shear force (in simple terms, the force of gravity acting downward, and being resisted by the bridge support points) occurs right at the supports.

If the bridge section failed in the middle, then it would likely be a bending failure. For this bridge section, the maximum bending force occurs at the furthest distance from the support (in this case, the midpoint of two support points).

[Pearls Before Swine]

Design is not assembly! Had the column been built, and even a few of the interior stays in place, the load at the ends would have been greatly lessened.

Agree with the rest of your comments.