Tolls pay for more than just building new toll roads. Though tolls go toward repaying the bonds sold to fund constructing new roads, they also pay for operating and maintaining the existing roadways and funding expansions and improvements.

Essentially, a toll road is never completely paid for, according to the North Texas Tollway Authority.

The state’s population is projected to increase to more than 30 million people by 2020, according to the Texas Department of State Health Services. As the population increases, toll roads may undergo improvement projects to accommodate for the increased traffic congestion.

Regularly scheduled increases of toll rates also help pay for future projects.

Gas taxes and vehicle registration fees do not fund the toll roads. That revenue is used to fund nontolled projects by the Texas Department of Transportation. Toll roads, on the other hand, are largely funded through the sale of bonds that are repaid through tolls.