By the end of 2021
Taihu Tunnel was completed and opened to traffic
It's the longest underwater tunnel in China
It's intelligent and ecological
How is such a tunnel constructed?
When will the invested capital of 9.9 billion yuan be recouped?
Jiangsu Province, China
Taihu Tunnel is part of the Changzhou-Wuxi section of the Suzhou-Wuxi-Changzhou South Highway
Taihu Tunnel
Length: 10.79 km
The construction started on January 9, 2018
It lasted 4 years
The tunnel officially opened to traffic on December 30, 2021
It is 43.6 meters wide, allowing 4 cars to pass side by side
The 10.79-kilometer tunnel is a two-way, six-lane highway
with a designed speed for motor vehicles of up to 100 km per hour.
Compared with the subsea part of the Hong Kong-Zhuhai-Macao Bridge, which is 6.7 kilometers long, the Taihu Lake Tunnel is significantly longer.
To be precise, it is 1.6 times that of the Hong Kong-Zhuhai-Macao Bridge tunnel.
You may be wondering
how difficult it is to build such a tunnel
Taihu Lake is located in the south of Jiangsu in the Yangtze River Delta.
Its surrounding tourism resources are rich
and involve a large number of environmentally sensitive areas
This means that environmental protection must be fully considered during the construction process.
The construction of the tunnel underwater is already very difficult,
and environmental protection factors have to be considered,
which makes the task even more difficult.
As an underwater tunnel,
the Taihu Tunnel has high requirements for the waterproofness of the tunnel construction materials.
At the same time, under the tunnel, in order to ensure that vehicles will not cause collapse when passing normally,
there are very high requirements for the compression resistance of the tunnel construction.
So it seems that the construction of Taihu tunnel is full of difficulties.
Because of the particularity of Taihu tunnel, there is not much experience at home and abroad to refer to.
China can only find out the solutuion on its own.
How did China overcome the core problem and build the tunnel?
Before the Taihu Tunnel, China had already built the Hong Kong-Zhuhai-Macao Bridge.
As world's longest sea-based project
the subsea tunnel section of the Hong Kong-Zhuhai-Macao Bridge adopted the immersed tube construction method,
but this method wsa not suitable for the Taihu Tunnel.
Therefore, the Chinese engineering team adopted the method of open-cut cofferdam.
That is to say, the method of advancing from the shore to the lake one by one.
To put it simply，
it is to make use of the shallow water depth of Taihu Lake, enclose a space with soil in the middle of the lake, and pump the water out of it for tunnel construction.
Although this increases the workload of the project, it can prevent the garbage generated by the construction from flowing into the surrounding waters.
After the construction is completed, it is only necessary to clean up the garbage and put the water into the earth dam to restore the local ecological environment.
The Taihu Tunnel is constructed by open-cut construction, which is different from the Hong Kong-Zhuhai-Macao Bridge Tunnel buried under 40 meters of water.
Although the Taihu Tunnel is very long and wide, it is also very shallow.
The average water depth of Taihu Lake is only 1.9 meters,
and the deepest part of the tunnel buried underwater is only about 4 meters.
Therefore, the open-cut process is more economical and reasonable, and the shield construction method cannot meet the width requirements of the Taihu Lake Tunnel.
Some people may ask, the tunnel will inevitably be eroded in the water, what if it leaks?
In order to do a good job of underwater waterproofing,
the Taihu Tunnel project team developed triple-six-layer waterproofing construction technology, adopted concrete structure for self-waterproofing，
set up waterstops and outer waterproofing of the tunnel, etc.
to achieve the construction goal of the Taihu Tunnel being watertight.
Compared with ordinary construction projects such as highways,
the construction of the Taihu Tunnel is so difficult.
Why does China have to spend money and effort to build it?
From the perspective of transportation in China,
at the same starting point, the length of the highway will be several times that of the tunnel project,
and the highway will have different speed requirements in different sections
which will extend the travel time of the public
After the Taihu Tunnel opens to traffic, not only can the distance between the two points be shortened, but the probability of traffic congestion is also relatively low.
As the back garden of Jiangsu, Wuxi pays special attention to environmental protection in the process of development.
From a long-term perspective, the construction of Taihu Tunnel is of great significance to the sustainable development of the environment.
The bold attempt of building Taihu tunnel has filled the gap of relevant engineering technology, and has great guiding significance for China's subsequent engineering construction.
It is expected that other lakes in China will also build underwater tunnels, which is not only a major breakthrough in China's underwater channels,
but also an important support for regional development
So how long will it take for this tunnel with an investment of 9.9 billion yuan to pay off?
If calculated according to the toll, generally speaking, the toll of a vehicle on the bridge is 50 yuan. If the maximum daily number of vehicles is 5,000, the Taihu Tunnel can earn 250,000 yuan a day,
and more than 80 million yuan a year.
This puzzled Western experts at first, because according to this calculation, it is difficult for the Taihu Tunnel to pay off.
In fact, the purpose of building infrastructure projects in China is very different from that in Western countries.
Western countries focus more on economic benefits, but China's construction of infrastructure projects is rarely for short-term economic benefits,
but more for the long-term development of surrounding areas.
The construction of infrastructure projects can promote the economic development of surrounding areas and open up transportation hubs across the country, which will bring huge social benefits.
The conventional asphalt pavement is hot mix asphalt, but the hot mix asphalt will produce a lot of harmful odors, so the asphalt pavement of the Taihu Tunnel is all cold mix.
Driving under the glowing ceiling of coloured LED lights feels like a dream.
For every kilometer there is a transverse traffic lane
This is a jet fan, which is intelligent. It can replace the fresh air and automobile exhaust through the pipes
keeping the air fresh in the tunnel, and also playing the role of fire prevention