The utility model discloses a bridge is with unmanned car of surveing in crack, including the automobile body, install the wheel under the automobile body, still install on the automobile body and observe subassembly and balanced direction subassembly, balanced direction subassembly including the leading wheel, guiding arm and the side -to -side adjustment spare that connect gradually, side -to -side adjustment spare is installed on the automobile body, the leading wheel contacts with the liang bi of bridge both sides. Controlling the orientation of whole device in advancing through balanced direction subassembly, preventing the skew, it can proper motion straight line driving under the unpiloted circumstances to have realized.