Analysis of Traffic Congestion Catastrophe on Freeway with Long Tunnel

On a freeway with long tunnel will raise a serious congestion in the access zone of the long tunnel during peak hour according to the experience on Freeway No. 5 in Taiwan, which has a long tunnel of 12.9 km in mountain area. The paper investigated the traffic congestion catastrophe characteristics by comparing with the traditional traffic flow model on the freeway. The results illustrate that there is the significant catastrophe characteristic dependent on the locations outside and inside of the tunnel. In this paper, using the catastrophe theory to model the macroscopic traffic model has higher correlation coefficients than the traditional traffic flow model. The catastrophe phenomenon on the entrance zone of the tunnel has more significant jumping feature than in the middle zone inner tunnel. Due to the traffic smoothing and safety following distance control within the long tunnel, the catastrophe feature will be reduced in the inner zone within the tunnel. According to the results, the traffic management strategy could help to reduce the catastrophe feature will be seen as effective alternative for improving the traffic performance of the freeway with long tunnel prospectively.