Or option C: greed. Any way you slice it, nuclear deterrence, missile defense, containment theory and more generally any initiative motivated by the fear of im

Or option C: greed. Any way you slice it, nuclear deterrence, missile defense, containment theory and more generally any initiative motivated by the fear of imminent nuclear holocaust and the Red Menace were huge windfalls for industrial corporations from the end of WWII onward. It was an effective way to siphon huge amounts of money from the postwar federal coffers for corporations that had made bank during the war, but were now left to justify why the government should continue shoveling money at them. Now, this may not be the case for Houston's interchanges in particular, but it was certainly the case for many such endeavors going forward for decades. See also: SDI ("Star Wars"). And of course, there were other factors like suburbanization/white flight and the ascendant automobile industry. But all of these potential motivators were (are?) very entangled and hard to fully extricate from one another.