A mobile tamping machine for tamping ballast under a railroad track includes a machine frame supported on undercarriages running on a main track for moving the machine in an operating direction. A tamping unit is mounted on the machine frame between the undercarriages, and a track lifting and lining unit for leveling and lining the main track is vertically and transversely adjustably mounted on the machine frame immediately ahead of the tamping unit in the operating direction, with drives being provided for vertically and transversely adjusting the track lifting and lining unit. An auxiliary lifting unit is mounted on the machine frame for lifting a branch track branching off the main track at a track switch. A common measuring system associated with the track lifting and lining unit and the auxiliary lifting unit is provided for controlling the lifting of the track switch. The common measuring system includes a mechanical measuring device, which connects the track lifting and lining unit to the auxiliary lifting device and is telescopically extensible transversely to the longitudinal direction of the machine frame, and a measuring sensor.