Abstract: The present invention relates to a full interchange urban road system and the traffic method of using it, characterized by that: the road system is a chessboard shaped double-layer road network. One layer is a motor way on the ground and another layer is a footway at a suitable elevation accordingly over the motor way. Alternatively, footways with proper width are located at each side above the two sides of the motor way, and the two side footways are connected across with a passageway, or part of a footway layer over an intersection of a collector street is constructed as a ring pathway or an aerial square. A turnaround passageway is designed between each two parallel expressways or under a separate fly-over type bridge arranged at an intersection of the two expressways. A minor arterial is provided between each of two parallel said expressways as a ramp for them and as a passageway leading to a subzone way.