Chaotianmen Bridge – “Door of the City”

Introduction

China has built numerous landmark bridges and highways over many rivers across the country. Some of the bridges and roadways are the best examples of technological and architectural advancements in the world. One of the marvelous achievements of China is the Chaotianmen Bridge which is named the “Door of the city”. It is the longest steel ark bridge built over the Yangtze River in Central Chongqing, China.

Chongqing has won the title of “Bridge Capital of China” because it has the largest number of bridges built across the city. The reason for building so many bridges is that the city covers the mountains and rivers. Yangtze and Jialing River alone have more than 50 bridges over their waters. In this article, you can get more information about Chaotianmen Bridge and learn more about its architecture, structural system and design, purpose, specifications, and the parties involved in building such a milestone bridge. 

The Design and Construction

The construction of the Chaotianmen Bridge was started in late 2005 and opened for traffic in April 2009. The architecture of this bridge was designed by the Institute of China Railway Major Bridge Engineering Group, a subsidiary of China Communications Construction Company (CCCC). The construction was carried out by China Harbour Engineering Company, under the supervision branch of China Railway Major Bridge Engineering Group. China Communications Construction Company is the BT owner of Chaotianmen Bridge. The cost of this beautiful and historical bridge was around $360 million. Below is a picture of the bridge taken during its construction.

Structural/Construction System

The arch bridge system of Chaotianmen Bridge makes a three-span continuous beam-stress system. The system contains two decks, a lower deck and an upper deck. This bridge is 1741 meters long and has a main span of 552 meters which is larger than the span of Lupu Bridge (2nd largest steel arch bridge in the world) located in Shanghai.

The central span is 488 meters long, and the midspan is 142 meters high. The central span shows the stress feature of the tied arch. The bridge has adopted the orthotropic steel plate (16mm thick) for its lanes in the upper and the lower deck with U-type ribs that are closed. The cross beam system and the stringer support the light rail. Below is the cross-section diagram of the two decks. 

Bridge Specifications

This section will discuss the materials used in constructing the bridge, the load it possesses and sustains, and the arrangement of lanes on the decks. Different types of steel were used to build this bridge with high-strength bolts. In the deck system of the bridge, steel Q345qD, Q370D, Q420qD, and Q345qD have been used for the main truss, which corresponds to 420 and 355 grade steels. High-strength bolts used are 35VB for bolts 10.9S – M30 and 20MnTiB for bolts M22 and M24. The steel used for high-strength nuts, washers, and bolts is 45# number high-quality carbon steel.

The permanent load of the bridge is 47.65 kN/m which includes the weight of pavement of the lower deck, pavement of the upper deck, the railing of the upper deck, the guarding railing of the upper deck, pavement and fence of pedestrian lanes, and lower deck of rail communication open bridge. It also includes the self-weight of the structure of the bridge. The variable load is the traffic load and the rail communication load of a team of five 19.52 m light metro trains at a time, having a maximum load of 140 kN.

Purpose

Chongqing is a big and mountainous city with rivers flowing through it. To connect the city with other parts of the country for trade and transportation purposes, the government of China realized the need to build bridges. Therefore, thousands of bridges have been built in the city for efficient and effective business activities and transportation.

Chaotianmen Bridge is one of those bridges built to connect the city with the Wulidian Subdistrict in Jiangbei District in the west and to the east with Danzishi Subdistrict in Nan’an District. The bridge is used for railway and highway transportation. The bridge has two decks. The lower deck has a two-way railway lane with one traffic lane on both sides, whereas the upper deck consists of three two-way highway lanes with pedestrian lanes on both sides.

Interesting Facts

• The bridge is a masterpiece of architecture and the bridge-building industry. Chaotianmen Bridge is so solid that during its construction, it tolerated the strongest earthquake in 2008, which was the strongest earthquake in the modern history of China.
• s took about 4.5 years to complete. Usually, projects like these are completed in China in record time, but this bridge was more complex in terms of its structure and construction. It was very expensive to build. The cost was around 3.2 billion Yuan which is equivalent to USD 500 million.   
• Chaotianmen Bridge has a height that matches a skyscraper. It is 142 m tall and has a width of 35.6 m. It also looks familiar with the famous bridge “Sydney Harbor Bridge” in Sydney, Australia.
• Three Gorges Dam is the world’s largest dam, and it is on the Yangtze River. Yangtze River itself is the longest river in China, stretched over 6,300 km.  
• Chaonianmen Bridge is equipped with colorful lights, which have increased its attraction and popularity. The bridge shines at night and gives the river and the city a beautiful view. This is a very high bridge, and Chongqing city has numerous tall skyscrapers. Therefore, it is illuminated at night to fascinate the visitors.

Such milestones are not achieved overnight and every day. It requires research, knowledge, will, resources, and determination to build something that is studied for years to come. Chaotianmen Bridge is one of the marvelous bridge-building achievements of China, if not the best one.

Reference:

1. civildigital.com/things-you-didnt-know-chaotianmen-bridge-world-record-steel-arch-bridge/
2. https://news.cgtn.com/news/2021-10-21/Chaotianmen-Bridge-in-Chongqing-milestone-in-China-s-bridge-building-14x5s8yAFMY/index.html
3. art-facts.com/famous-bridges/

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