The functional design phase analyzes the program conditions such as street traffic, site configuration, number of vehicles to be parked, building codes, zoning requirements, environmental concerns, and the nature and character of the traffic generators. Combining this information, optimum vehicular and pedestrian flow patterns are developed. Parking space layout and a method of operation is developed to arrive at a functional design.

The functional design phases proceed to more definitive terms in describing the proposed facility. Dimensions are more precise, decisions regarding structural systems are made, architectural features are explored and graphics selected. Entry and exit requirements are determined, and lighting and draining systems are defined. Landscaping objectives are established.