The Texas Transportation Code states that "an operator may not drive at a speed greater than is reasonable and prudent under the circumstances then existing". Therefore, regardless of the posted speed limit, every driver has a duty to drive at a reasonable and safe speed for the conditions at that time.
All roadways in Texas have a default speed limit called the prima facie limit based on the type of roadway. This applies to residential streets (30 miles per hour (mph)), alleys (15 mph), interstates (70 mph), etc. For residential streets, state law does allow the Town Council to reduce the prima facie limit to 25 mph by Ordinance and then post the speed limit, making it effective. The Town Council has done this on the residential streets of Providence Village. State law does not allow the residential speed limit to be set lower than 25 mph, nor does it allow the speed limit to be set lower than 15 mph on alleys.