World-class Bridge across the Taiwan Strait: Pingtan Straits Rail-cum-Road Bridge

The Pingtan Straits Rail-cum-Road Bridge is a crucial control project for the Fuzhou-Pingtan Railway and the Changle-Pingtan Expressway under construction. The bridge was started in November 2013, with the lower part being a two-lane first-class railway with a speed of 200 kilometers per hour and the upper part being a six-lane expressway with a speed of 100 kilometers per hour. Three out of the four navigation channel (fairway) bridges have now been closed, and the remaining Guyumen cable-stayed bridge is expected to be completed at the end of September. At the end of November, the framing conditions will be met for the cross-sea bridge. In February 2020, the entire length of the Fuzhou-Pintang Railway will complete paving. After the completion of the bridge, the drive from Fuzhou to Pingtan will be reduced from one and a half hours to half an hour.

The construction conditions of the Pingtan Straits Rail-cum-Road Bridge are far worse than those of the Donghai Bridge, the Hangzhou Bay Bridge and the Hong Kong-Zhuhai-Macao Bridge, along with higher difficulty and risk. It is currently the most difficult straits bridge under construction in the world.

The strait where the Bridge is located as well as Bermuda and the Cape of Good Hope are known as the world's three major seas with a draught, accompanied with large winds, deep water, high waves and undersea hard rocks. According to statistics, the number of days of having winds of Beaufort Force 6 and above is more than 300 days, and that of Beaufort Force 7 and above is more than 200 days. The highest wave can reach up 9.69 meters, and the average number of typhoons is 3.8 a year.

You can imagine the difficulty to build a cross-sea rail-cum-road bridge under such a harsh marine environment.

To address the harsh environment at sea, reduce construction safety risks, and improve construction efficiency, the factory-like erection of the large-scale complete bridge openings has become a must-have. However, the weight of the opening steel beam after welding will be over 1,000 tons, based on which the lifting weight needs to be nearly doubled to ensure a stable lifting process in windy conditions. In other words, it is necessary to lift more than 3,000 tons to accurately complete the erection in the air. Notably, there was no crane ship for support.

To this end, the construction entity China Railway Major Bridge Engineering Group Co., Ltd. (MBEC) cost 340 million yuan to build a "magic tool" for bridges, double boom lifting ship "Seagull Bridge", in 3 years. The crane comes with a lifting capacity of 3,600 tons, equivalent to the weight of 2,400 cars, and the main hook's lifting height up to 110 meters, equal to 39 stories. The technology used is the first of its kind in China.

On January 22, 2018, the "Seagull Bridge" crane ship steadily lifted and erected a 3,400-ton steel truss girder onto the top of the pier, marking the completion of the erection of the heaviest steel girder for the Bridge. This also broke the world record of erecting the heaviest steel girder for the entire opening of a bridge.

In the construction process, the following China's first construction technologies were adopted: factory-like full-rib all-welding manufacturing technology for steel truss girder, symmetrical cantilever construction technology for full large ribs between two sections, and the full-section closure technology for full rib of the steel truss.

Currently, 12 patents have been declared in terms of new structures, new processes, new methods and others of the bridge, making it an innovative bridge. The construction of the bridge will build up valuable experience for the cross-strait project planned and constructed in the future. At the same time, it provides investment basis for the construction of China's cross-strait bridges through the construction norm tracking and measurement of offshore bridges.