Straddle type monorail PC track girder construction method inside circular cross section tunnel

The invention discloses a straddle type monorail PC track girder construction method inside a circular cross section tunnel. The method comprises the following steps of providing a girder erection machine and a girder transporting vehicle capable of walking on the hook face; a PC track girder is fixedly installed on the girder transporting vehicle, and the girder erection machine is put in place;the girder transporting vehicle transports the PC track girder into the girder erection machine; a transverse clamping device of the girder erection machine is started, the PC track girder is lifted,and the girder transporting vehicle exits from the circular cross section tunnel; the girder erection machine erects the PC track girder according to a design construction drawing, the girder transporting vehicle is returned to transport a next PC track girder; after erection of the girder erection machine is completed, the next PC track girder is erected when the girder erection machine is put inplace forwards. The method