Nothing, as far as I know. And some of that could probably be tax-financed if some of the state gasoline tax wasn't being diverted to public skrools, DPS, and other things.
I-35 is being widened to six lanes south of DFW, but widening it beyond that would be a really expensive proposition, since TxDOT would have to purchase expensive (and presumably developed) land along the highway. And don't you mean I-27?
I meant I-29 KC through the Dakotas to Winnepeg.
As a matter of fact, they're widening/improving all the Interstates to and from the Dallas/Ft. Worth area.
As far as I-35E, south of Dallas, if you've ever driven that stretch, there's not a lot of development.
Would it cost billions to add additional lanes? No!
If necessary, the additional lanes could be tolled not, by a foreign company but, by the state.