From the environmental point of view, viaduct will have a certain impact on land use and urban landscape on both sides, and it is easy to produce noise; The tunnel has little interference to the ground traffic.
2, the cost is different
The cost of viaduct is lower than that of tunnel, and the construction and later operation cost of tunnel far exceeds that of viaduct. At the same time, the safety of the tunnel is not as great as that of the viaduct, so it is relatively difficult to rescue and organize traffic from the tunnel to the viaduct.
3. Different definitions
The Yangtze River Bridge, in a strict sense, only refers to the bridges on the Yangtze River below the Minjiang Estuary in Yibin, but usually refers to all the bridges on the main stream of the Yangtze River. After the opening of the Yangtze River Tunnel, it is expected that about 20% of the river-crossing traffic in the downtown area of Wuhan will be diverted to ease the traffic pressure on the first and second bridges of the Yangtze River.
4, the difficulty is different
Bridge repair mainly adopts high-tech and high-precision pouring engineering, and uses high crane to accurately and seamlessly splice the bridge deck with good pouring plasticity. However, for the calculation of the distance between the two sides of the bridge, the material selection of the bridge deck is a very professional problem, and there can be no error.
There is a lot of unpredictability in tunneling, and many times we don't know the specific situation in the mountain.