Texas Transportation Code - TRANSP § 544.004. Compliance With Traffic-Control Device

(a) The operator of a vehicle or streetcar shall comply with an applicable official traffic-control device placed as provided by this subtitle unless the person is:

(b) A provision of this subtitle requiring an official traffic-control device may not be enforced against an alleged violator if at the time and place of the alleged violation the device is not in proper position and sufficiently legible to an ordinarily observant person.  A provision of this subtitle that does not require an official traffic-control device is effective regardless of whether a device is in place.