Abstract: Various conditions can restrict the connection between tunnel exits and surface roads. Moreover, under certain conditions during the actual design of projects, the corresponding indexes given by relevant regulations are not rational. Therefore, a case study is conducted on the rivercrossing tunnel of the Heyi road in Quzhou, China. Based on the running speed from the aspect of drivers, a calculation model is established for the safety distance between the tunnel exit and the road intersection. The index requirements of the distance between the tunnelground connection point and the downstream road intersection in the 〖WT5BX〗Code for Design of Urban Underground Road Engineering〖WT5《TNR》〗 are consistent with the safety distance between the tunnel exit and the road intersection proposed in this study, which is suitable for urban tunnels with opensection structures. For urban tunnels without an opensection structure, the distance between the tunnel exit and the lightcontrolled road intersection should not be less than 1.5 times the stopping sight distance, which is larger than that in the code(1 time). Furthermore, considering the driving comfort, the SIANAL94 intersection queuing length model is used to establish a model for calculating the ideal distance between the tunnel exit and the road intersection. It is concluded that when the queue length of a single lane is overly large, the relevant specifications are not applicable. The actual distance required by the project should be calculated according to various factors, such as the queue length of the traffic volume and the number of lanes. Finally, the optimized connection measures are proposed in the design of the rivercrossing tunnel of the Heyi road.

Key words: urban tunnel, road intersection, running speed, safety distance, SIANAL94 calculation model, ideal distance