The City of Huntsville, Alabama, is hereby authorized to acquire and operate passenger excursion trains within Madison County, Alabama, upon the tracks of any public or private railroad company based upon agreements for such operation between the city and any such public or private railroad corporation or other entity. The city is authorized to acquire, maintain, and operate such engines, cars, and other equipment as it deems necessary and useful for the operation of any such passenger excursion train, and may operate such excursion trains directly or through any board or commission of the city created by ordinance and duly authorized to establish and operate passenger excursion service on behalf of the city. Provided, however, that in no event may the horn or whistle volume or decibel level of any passenger excursion train exceed the volume or decibel level of any other train or locomotive that uses the same railroad track or line as that used by the passenger excursion train.