Freeway tunnel effect of travel time based-on a double lane traffic model
Yongliang Zhang, M.N. Smirnova, Jian Ma, Zuojin Zhu, Н.Н. Смирнов
Abstract
Speed limit of freeway tunnel restricts car driving behaviors. To explore the tunnel effect of travel time, a double lane traffic model is put forward, and a compensative function of mean travel time is simply introduced in this paper. The model describes the net lane-changing rate using the ratio of characteristic lane changing time to traffic relaxation time, assumes that the cars on both lanes of the tunnel have the same equilibrium speed, but the speeds on both lanes of normal section are different. It is assumed that the road length is 100 km, and the tunnel length is 7.5 km except for the case of seeking tunnel length effects. The model is used to build a simulation platform. Numerical results indicated that when the initial road density normalized by jam density is above 0.2, the tunnel causes a congestion region just upstream the tunnel inlet, provides a smooth region just downstream the tunnel outlet, can affect the traffic flow pattern significantly. But the tunnel effect of travel time is small, as the tunnel can merely slightly increase the mean travel time. The on/off ramp flows play a crucial role in the formation of traffic flow pattern.