The speed restrictions set forth in § 15-7.2 on roadways, streets, highways, or boulevards, or portions thereof, shall be ineffective unless legible signs are erected and maintained indicating the maximum speed permissible thereon.
(Sec. 15-7.3, R.O. 1978 (1983 Ed.)) (1990 Code, Ch. 15, Art. 7, § 15-7.3)