(a) On an electronic sign each message must be displayed for at least eight seconds. A change of message must be accomplished within two seconds and must occur simultaneously on the entire sign face.
(b) An electronic sign must:
  (1) contain a default mechanism that freezes the sign in one position if a malfunction occurs; and
  (2) automatically adjust the intensity of its display according to natural ambient light conditions.
(c) The owner of an electronic sign shall coordinate with local authorities to display, when appropriate, emergency information important to the traveling public, such as Amber Alerts or alerts concerning terrorist attacks or natural disasters. Emergency information messages must remain in the advertising rotation according to the protocols of the agency that issues the information.
(d) The department will share the contact information with the appropriate local authority that has jurisdiction over the location of the electronic sign.

Source Note: The provisions of this §21.206 adopted to be effective March 14, 2018, 43 TexReg 1446