(a) Excluded from these regulations are:

1. (1) advertising devices which are not visible from any traveled portion of the Thruway system;
2. (2) advertising devices for which the attraction is deemed incidental by the Thruway Authority;
3. (3) directional or other official signs and signals erected or maintained by the State or other public agency having jurisdiction; and
4. (4) information required or authorized by law to be posted or displayed thereon.