On the Traffic Flow Characteristics in Kanmon-Tunnel

This paper describes some traffic flow characteristics in Kanmon-tunnel. Kanmon-tunnel is an undersea two-lane road tunnel and 3461.4m long. Traffic data used in this study were obtained by analizing pictures recorded through 5 watching TV-cameras selected from 26 cameras installed in the tunnel. Mean headways of sub-compact and compact cars, about 5.0 and 4.0 seconds respectively, were nearly constant untill the sag of tunnel and decresed a little after the sag. On the other hand, mean headways of midium-sized and large-sized cars were almostly constant, both about 7 seconds, up to the sag, and it incresed to 9 seconds in the up-grade section after the sag. Platoon grew acooding to progress of traffic flow and mean platoon size changed from 5.5 to 7.5 veh./platoon. The rate of midium-sized and large-sized cars occupied in leaders of platoon increased with distance from tunnel entrance, and the rate of sub-compact and compact cars in leaders decreased. So, the headway distribution changed by location though traffic volume did not change. It became clear that midium and large-sized cars had a great effect on tunnel traffic flow.