AUSTIN, Texas The Lone Star State continues to push highway speed limits into the stratosphere well, certainly the highest in the U.S.

Gov. Rick Perry signed into law a bill that permits the speed limit on certain new roadways to be set at 85 mph. The law requires the Texas Department of Transportation to perform engineering and traffic studies to determine whether the speed is appropriate on new construction.

Another new law increases speeds on most rural highways to 75 mph day and night as long as studies deem it safe. In addition, any speed differential between cars and commercial vehicles is eliminated.

Finally, the existing 80 mph day-time speed limit for cars on more than 520 miles of Interstates 10 and 20 in west Texas will apply to all vehicles throughout the day.

A separate provision in the 85-mph speed limit effectively buries, once and for all, the once-ballyhooed highway system that came to be known as the Trans-Texas Corridor.

At one time, the corridor was championed by Gov. Perry. It would have been a 4,000-mile network of toll roads, including the Texas segment of a proposed NAFTA superhighway stretching from the Mexican border to Canada.

The multibillion-dollar Trans-Texas Corridor was debated at the statehouse for most of the past decade until it was declared dead in 2009. However, concern about language still on the books spurred lawmakers to take additional action.

While the corridor project has had a stake driven through it, the pursuit of tolling in Texas is far from a dead issue in the state capital at Austin.

Lawmakers and the governor have given the Texas Department of Transportation and local tolling authorities the right to sign public-private partnerships for as many as 10 toll roads.

The so-called comprehensive development agreements include work on a 28-mile segment of Interstate 35 East between Interstate 635 and U.S. 380; a nine-mile portion of state Highway 183 between state Highway 161 and I-35 E; five segments of the North Tarrant Expressway project, and the Grand Parkway, state Highway 99, in Houston.