When any bridge operator shall be about to open the span of any bridge within the limits of the City, he shall give notice to land traffic of his intention to open such movable span by raising a flag, ringing a bell, flashing a red light, or other signal. After notice is given, no person shall walk, ride or drive any vehicle upon such movable span while the bridge operator is opening or closing the same.
(1980 Code 92.36)