"The two truckers that lost their lives in this incident could see that the water was crossing in front of them a little higher than the existing pavement; however both assumed it was water crossing the road and figured they could drive through it slowly, not knowing of course that there was no road left."
Note how deep the gully is. Now imagine how the truckers saw it. Surely, it must have looked like a pool of water flowing across the lanes.
Please do not drive into a flooded roadway. Not even slowly, thinking to back out if it gets deep. You may not get the chance.
I used to attempt to cross a shallow-looking flooded highway. (Because a Tracker has lots of clearance.) Never again.