Texas law requires that speed limits on state roadways be set at the state maximum, unless traffic and engineering studies show a need to alter a speed limit for safety reasons.
Maximum Speed Limit
The law sets the maximum at 70 mph, but allows the Texas Transportation Commission to establish a maximum speed limit of 75 mph (80 mph or 85 mph if the highway is designed to accommodate that speed) on the highway system if that speed is determined to be safe and reasonable after a traffic or engineering study. A maximum speed limit of 80 mph within 10 counties on Interstate 10 and Interstate 20 is also permitted.
City governments and TxDOT must conduct traffic and engineering studies according to requirements outlined in TxDOT's publication, Procedures for Establishing Speed Zones, when setting a speed limit on the state highway system. Speed limits on state highways may be set by the Commission or by a city if the highway is within city limits.
Citizen requests for speed zone studies on highways should be made to the TxDOT district office with jurisdiction over the roadway.
TxDOT only has jurisdiction over setting speed limits on the state highway system. Questions about speed limits on city streets or county roads should be directed to the transportation departments of these local governments.