Parking lot layout, landscaping, buffering, and screening shall be provided to minimize direct views of parked vehicles from streets and sidewalks, avoid spillover light, glare, noise, or exhaust fumes onto adjacent residential properties, and provide the parking area with a reasonable measure of shade, when trees reach maturity. In order to achieve these objectives, parking lots exposed to view shall be surrounded by a minimum of a four-and-one-half-foot-high, year-round visually impervious screen, hedge, or wall. The height of any required screen, hedge or wall shall decrease where driveways approach sidewalks or walkways in order to provide adequate visibility of pedestrians from motor vehicles, and shall not interfere with clear sight triangle requirements.