Mobile County Public Works is a city department that constructs and maintains various new and county-owned facilities. It supervises the design of new facilities that are constructed with the county funds and also issues permits and inspects building construction on private property in unincorporated portions of the county through its building inspection department. The department maintains more than 90 county-owned buildings, an airport, various parks, over 1,300 miles of roads, drainage facilities, bridges, traffic control devices and a countywide 800 mega hertz trunked radio system. It administers contracts approved by the county commission, including professional engineering and construction contracts, and other construction projects awarded by the commission. The department s services also include planning, geographic information system mapping of all roads in the county, subdivision and commercial site plan reviews, bridge construction, and road and drainage improvements.