The lowest part of any such canopy, sign or of any non-rigid awning, or any support thereof which extends over any public way shall be at least eight feet above the level of the walk or public way over which it extends; but no such sign shall be maintained over any public way used by vehicles if any part of its support or of the sign is less than fifteen (15) feet above the level of such public way. (Prior code § 33-4-7)