(a) Construction of prima facie limits. The prima facie maximum speed limits fixed by the legislature or established by zoning authority will be construed to be the maximum permissible speeds under normal conditions and speeds in excess of such limits will be considered illegal.
(b) Interpretation of Texas Transportation Code, §545.363(a).
  (1) The exception "except when reduced speed is necessary for safe operation" will not apply when it is practicable for the offending driver to drive onto the shoulder and allow the impeded traffic to pass.
  (2) The exception "except when reduced speed is necessary ....in compliance with law" will be interpreted to exempt at all times a driver of a vehicle or combination of vehicles who is driving at or near the maximum legal limit for that vehicle or combination of vehicles.

Source Note: The provisions of this §3.24 adopted to be effective January 1, 1976; amended to be effective August 4, 1998, 23 TexReg 7841; amended to be effective May 9, 1999, 24 TexReg 3527