Precise and rapid anti-collision hoisting method for ramp steel box girder connected into existing viaduct

The invention discloses an accurate and rapid anti-collision hoisting method for a ramp steel box girder connected into an existing elevated road. The method comprises the following steps: carrying out lengthening and support changing treatment on an existing cross beam of the highway; all supporting frame bodies are built between every two adjacent lengthened cross beams, and transportation rails are laid on the supporting frame bodies; each transportation platform truck is hoisted to the corresponding first section of transportation track, and then each section of steel box girder is hoisted and placed on the transportation platform truck in sequence; all the sections of steel box girders are sequentially conveyed to the construction position along the conveying rail; the two adjacent steel box girders are welded; the whole section is driven to descend until the two ends of the section abut against the adjacent lengthened cross beams respectively; each transportation platform truck is transported to the mai