After the extreme rainstorm disaster in Zhengzhou, urban roads, subway tunnels and other transportation projects are potentially to encounter dangers such as the road cavity, tunnel deformation and water seepage. In order to find out these hidden dangers, according to the categories of hidden dangers after the rain disaster and the characteristics of various detection methods, through the combination of vehicle mounted 3D ground penetrating radar, towed transient electromagnetic detection, mobile 3D laser scanning and other detection methods, the emergency detection of road cavity and tunnel diseases was carried out. The results show that the combination of vehicle mounted 3D ground penetrating radar and towed transient electromagnetic detection can effectively avoid the limitations of a single method and quickly find out the diseases, such as the cavity and the leakage of transportation engineering. The safety status of tunnel engineering can be quickly found out by using 3D laser scanning and then using the ground penetrating radar to investigate the main disease information of tunnel structure in detail.