The mainline toll station and tunnel are the important parts of the expressway system. The rationality of the clear distance affects the traffic capacity and safety. Based on the characteristics and the implementation status of expressway construction, combined with the relevant standards and research results at home and abroad, the clear distance between tunnel exit and mainline toll station has been defined and divided into the light adaptation distance, the traffic signs recognition distance, the operation distance and the lane confirmation distance. On the basis of analysing various constraints, the research has been carried out to establish a calculation model for the clear distance between the tunnel exit and the mainline toll station. It is proposed that under the secondary service level of the 4-lane expressway, under the design speed of 120km/h, the general value of the clear distance between the tunnel exit and the mainline toll station should be greater than 750m; when it is limited by terrain and route corridors, the minimum clear distance should be no less than 600m. It provides a valuable reference for the design and management of tunnels and mainline toll stations.

CICTP