(武汉工程大学土木工程与建筑学院， 湖北 武汉 430073)
阳丹（1999—）， 女， 硕士在读， 研究方向为交通运输工程。
The analysis and Calculation of unblocked reliability of urban underpass are very important to the accessibility and safety of the road network in the whole city. By analyzing the existing study results, the operation characteristics of urban underpass are studied. Several calculation methods of urban underpass reliability are proposed, which are based on the underpass functions, saturation, traffic flow density and traffic flow statistics. Taking East Lake Channel in Wuhan as an example, it is proved that the reliability of the East Lake Channel calculated by the algorithm is consistent with the traffic conditions obtained by the actual investigation. The result shows that it is practical to analyze the operation state of urban underpass by using unblocked reliability.