Every road entering the City of Berkeley which has a sign marking the City limits as of the date of the passage of this act will also be marked, equally prominently, with a sign reading "Nuclear Free Zone, established by City of Berkeley initiative ordinance, 1986." These signs shall be posted no later than January 1, 1987, and shall be at least two feet by three feet. (Ord. 5784-NS § 11, 1986)