A bi-transitional road way removal tiered raceway side-by-side storage-mechanical parking system used in the unilateral roadway, which belongs to the traffic and transportation field, comprises stockroom-type frames, a roadway, parking areas, wheel holding raceways, external well roads, lifting handlings, vertical shift handlings, a separating and positioning horizontally moved delivery device, a storage and taking out transitional area; on the stockroom-type frame between two road ways, each layer is provided vertically with the parking area along the road way, the wheel holding raceway is arranged horizontally thereabove to hold many cars side by side; in the bi-road way, a vertical shift handling carries out the separating work; well roads with lifting handlings and the storage and taking out transitional area are arranged along the external side of the road way; lifting handlings, vertical shift handlings and the storage and taking out transitional area are also provided with the same wheel holding race ways; on the storage area and the storage and taking out transitional area, the separating and positioning horizontally moved delivery device, which can move horizontally and extend into the vertical shift handling and is arranged between the front wheel holding race way and the back wheel holding race way, can be used to storage, take out and move horizontally cars. The invention has a large capacity of bikes and is high in working efficiency.