Why does Dallas City Council want to replace the trees growing in the river with a toll road?

Why do we have trees growing in the Trinity River and just why — or maybe the question is how — does anyone plan to put a toll road there? We can’t keep the bike trail from flooding. How will a much larger toll road not flood?
Every time I post this, someone answers that the road will be elevated. No it won’t. It won’t go under the two Margaret bridges and the historically designated other bridges if it’s elevated at the points where these pictures show flooding.
Putting a highway — or any kind of through road — here, where we’re in our second year of flooding, is stupid at best and a huge waste of a few billion dollars at worst. Any roads should only be for access to the park area — and it will flood, by the way.
And, by the way again, these aren’t hundred-year floods. Since the 1980s, the Trinity has flooded like this during two years of every decade.