If elevating machines or hoisting apparatus, operated or controlled by other than hand power, are used in the construction, alteration, or removal of any structure, the owner, contractor, or sub-contractor shall, during the use and operation of the elevating machine or hoisting apparatus, provide and maintain an adequate system of communication by signals, so that prompt and perfect communication may be had at all times between the operator of the engine or motive power of the elevating machine or hoisting apparatus and the employees or persons engaged thereon or using or operating it.  The officers of the city charged with the enforcement of the building laws shall enforce this Section.  If such officers fail to do so, the police authorities shall, pursuant to the terms of this Part, enforce the provisions of this Section.