"A 6 cent per gallon gas tax increase will raise around $840 million per year $630 million goes to transportation, $210 million goes to education
"$610 million per year is enough to prevent all freeway-to-tollway conversions, as well as build many of the new highways we need."
In addition to that, if the portion of the gas tax that was (mis)directed toward education was redirected toward roads, things would be even better. And if the gas tax were raised, as some advocate, by ten cents per gallon instead of six, things would be even better, and it would still be lower than it is in eight other states.
Why are you so fascinated with the politics of road construction in Texas? It's equivalent to me having an obsession with fishing regulations in Chesapeake Bay and setting up a ping list for that topic.