Rapidly-installed protective structure crossing existing bridge in city

The utility model relates to the field of construction of urban bridges crossing existing lines, in particular to a rapid installation protection structure for crossing existing urban bridges. Comprising a bottom support system and an upper working platform, and the support system comprises a plurality of stand column systems and tie bar systems used for connecting the adjacent stand column systems; the stand column system comprises a first fast splicing unit and a second fast splicing unit. The tie bar system comprises a steel stand column and a second connecting rod used for connecting the steel stand column of the stand column system. One side of the steel stand column is movably connected with the inclined strut through a movable connecting plate and a pin shaft; the top end of a steel stand column of the support system is connected with longitudinal beam I-shaped steel, a plurality of support cross beams are connected between the two I-shaped steel, steel plates are laid on the support cross beams, and t