The analysis includes these factors - current : channel and bridge structure . it puts forward the importance and value of the study with the probability evaluation of each factor act on the navigational safety 根据可靠性理论分析桥区河段水流、航道及桥梁结构等影响船舶安全航行的因素,并对各因素影响船舶安全航行情况进行概率评估,从而提出本课题研究的重要性及意义。