The last legislative session authorized the Texas Department of Transportation to establish 75 mph speed limits on roads where that can be done safely. Speed limits are being raised on segments of I-10 and I-45 leading out of Houston, as well as I-35 and other highways in the state. TxDOT's Mark Cross says sign changes are being done over the next 90 days.
"It will be going into effect as we make changes, old signs go down and the new signs go up."
Recently, separate night-time speed limits were eliminated, as well as separate truck speed limits. And there are actually some 80 mph zones on some Texas roads.
"A number of years ago, the state passed legislation that allowed 80 mph speed limit maximums on segments of highways that are located in areas of low population density. So there are segments of I-10 and I-20 in West Texas, which is mainly where these 80 mph speed limits are."
Engineering studies have been conducted to show where higher speeds could be posted safely.
"Basically what we do is go out to a segment of roadway, look at the accident history, look at the design of the roadway, the topography, the number of access driveways. Probably the most important thing is to look at what 85 percent of the traffic is already traveling at, that particular section of roadway."
The new 75 mph designations are affecting some 1,500 miles of interstate. But again, it's not official until the signs go up.