In chapter 4, design criterions were established with risk approach, so as to balance risk of failure and cost on reduction of accidents and to achieve best design on economic.

• 第四章对船桥相撞事故进行风险分析，运用风险理论建立桥梁结构设计准则，使得桥梁结构失效的风险和减少这种风险的建设费用达到平衡，由此获得预先确定的安全度以及经济上最优的设计。