I think your headline, and arguments for a bridge because of these two sad events, are way over the top – especially if what was being proposed were the same as the two monstrosities erected at the Bognor Bridge roundabout, and more recently Tangmere.
I suspect they are the work of the Highways Agency and drastically over-engineered for the duty required – the latter would be more appropriate for battle tanks, hence the cost.
Having erected a very expensive bridge (when most people can readily identify an alternative reason for spending £2m more effectively), how do you persuade people to always use the bridge for safety?
My casual observation of these two bridges tells me that potential users do not readily use them at all, let alone frequently enough to justify the cost and ugliness.
The same is true of an even larger bridge spanning the A27 to Farlington Marshes/Havant. The Donnington roundabout bridge is only slightly more used at limited times of the day, mainly, I believe, because it is more user friendlier in itself, and not it’s own worst obstacle.
If the decision was mine, I would forget any bridges and erect a high centre road barrier with a controlled chicane pedestrian lane, high intensity road lighting and pedestrian operated traffic lights.