A bell of at least thirty pounds’ weight and a steam or air whistle shall be placed on each locomotive engine or interurban car and such bell shall be rung or such whistle sounded by the engineer, fireman or motorman at the distance of at least five hundred yards from the place where the railroad crosses any public highway, street or traveled place and be kept ringing or whistling until the engine or interurban car has crossed such highway, street or traveled place. If such engine or car shall be at a standstill within less distance than one hundred rods of such crossing such bell shall be rung or such whistle sounded for at least thirty seconds before such engine or interurban car shall be moved and shall be kept ringing or sounding until such engine or interurban car shall have crossed such public highway or street or traveled place. A gong of not less than ten inches in diameter may be placed upon interurban cars in lieu of a bell as herein required and shall be sounded as herein provided.