What may well be the largest crowd ever to attend a construction project ground breaking — the onlookers were estimated to number more than 50,000 — gathered on June 8, 2003, for ceremonies marking the start of work on China’s Hangzhou Bay Trans-Oceanic Bridge.
Liu Ting, deputy director of the project, described the bridge as the largest construction job thus far undertaken by the government of China. At the staggering cost of $1.7 billion, the bridge will connect Cixi and Zhapu, and when completed will be not only the longest sea span in the world but also the first of its type to be built in China.
Hangzhou Bay is located on the East China Sea, and the bridge will cross the Yangtze River Delta. Its construction will cut approximately 74.5 mi. (120 km) from the journey between Ningbo and Shanghai. The shorter travel time that will then become possible — cut to approximately two hours, or half the time it currently takes to make the journey of 186 mi. (300 km) around the bay — is expected to encourage and increase economic opportunities and development in Zhejiang Province and its cities, particularly Shanghai.
With tens of thousands of workers on the project, the local economy already has received a boost, not least in the price of land — the cost of an acre of wasteland reportedly rose a hundred-fold in two years.
Boasting a population of 135 million and the home of more than a dozen of the most prosperous Chinese cities, the Delta already is one of the flourishing commercial regions in China. Although its residents represent only approximately a tenth of the country’s population, it produces more than 20 percent of its gross domestic product.
Popular Tourist Destination
Hangzhou Bay is a particularly challenging site for construction. The area is subject to typhoons and seismic disturbances, so the bridge was designed to maintain structural integrity even if experiencing earthquakes up to the seventh level of the Richter scale. Natural gas also is present in the bay and its location and effect on the seabed had to be investigated and arrangements made for its safe release before pile driving could begin.
The bay also features one of the tallest tides in the world. They can be as high as 25 ft. (7.5 m), moving between 15 and 18 mi. (24 to 29 km) per hour. These tides are considered a natural wonder and are a major tourist attraction. Over the years several million visitors have viewed them and special provisions were made for tourists in the project’s design.
The bridge will feature off-ramps leading to a sea platform with an area approximately 111,111 sq. ft. (10,000 sq m). This artificial island is to be built on piers to ensure its presence does not interfere with the famous tidal movements, and will feature gas stations, restaurants, and hotels as well as a tower offering travelers excellent views of the phenomena. Emergency service personnel also will be based there.
History of the Project
So complicated was the planning process, construction could only begin after several hundred experts from various countries had conducted more than 100 studies over the course of a decade.
Now more than half completed, the “S”-shaped toll bridge is a stayed cable structure with an overall length of 22 mi. (36 km), of which its trans-oceanic section will stretch 20 mi. (32 km). It will be 203 ft. (62 m) high, allowing container ships free passage. Designed to last for a century, the span will be completed in 2008 and opened to traffic the following year. Vehicles will travel its six lanes at up to 62 mph (100 km) an hour, with 52,000 crossing daily in 2009, rising to an estimated 80,000 by 2015 and 96,500 in 2026.
The bridge will form part of a highway approximately 3,250 mi. (5,200 km) long between Tongjiang to the northeast and Sanya in the south, part of an extensive $242-billion highway program, which will have constructed 52,817 mi. (85,000 km) by 2030.
The China Railway Bridge Bureau Group Company Ltd. is project contractor. Founded in 1953 and now employing approximately 6,000 employees in China and elsewhere, it also built the first bridge constructed over the Yangtze River.
Numerous Chinese companies were and are involved in the giant effort, including three corporations under the China Railway Ministry — the No. 4 Bureau, headquartered in Hefei, the No. 2 Bureau, based in Chengdu, and the No. 19 Bureau, located in Liaoyang — which worked on spans near the southern shore.
The project is, however, global in nature, with companies on four continents contributing their expertise.
Because of the intricate nature of the work site, GPS services were needed for initial survey work. Real-time kinematic high accuracy GPS systems from Trimble, a U.S.-based manufacturer, were used on piling barges and floating cranes positioning piers and moving pre-fabricated concrete sections into place to ensure this vital work was carried out with pinpoint accuracy.
A GPS reference station network using Trimble CORS (Continuously Operating Reference Station) GPS receivers was established at the job site to provide real-time positioning 24/7 in all weather conditions.
“The bridge project could not be done without a unified GPS reference station system,” said Xiao Genwang, chief director of the control center and deputy general manager of the 1st Engineering Co. Ltd. under the China Railway Bridge Bureau Group.
“The stations can provide information for all builders and surveyors, thus ensuring the coherence of data. In addition, the 12 bid sections could be under construction any time, which requires reference stations that operate at all times and under all weather conditions. As a result, the Trimble CORS system has become very important to us.”
The importance of the GPS equipment is highlighted in the positioning of piers, which are fundamental to the bridge. Any error in positioning could render a pier useless, resulting in irreversible damage to the project. Because of the rough waves and high tides of Hangzhou Bay, pier positioning has proved uniquely difficult. GPS technology has become crucial in responding to these challenges.
Trimble has provided GPS equipment for similar projects. It was involved in the construction of the Oresund Bridge, a joint Danish-Swedish project to construct a cable-stayed two-level steel and concrete structure linking the two countries. The upper deck of the bridge carries a highway and the lower a railway.
Zhuozhou Sanbo Bridge Formwork Manufacture Company Ltd. located in Zhuozhou, Hebei, 37 mi. (60 km) from Beijing, also is working on the bridge.
“We specialize in the fabrication of formwork, supporting, and concrete mechanical equipment for civil engineering,” said general manager Qiuli Yang. “Beam launching and the deck system are under construction. Sanbo has 120 employees working on the job, fabricating formwork for the deck system.”
Although the nature of the site and project are challenging, Yang noted that formwork fabrication has gone smoothly. “I think Sanbo is acting as a very important collaborator in this great project,” he added.
International Construction Equipment Inc. (ICE), based in Matthews, NC, began work on the project in July 2004, when the first steel casing — with a diameter 10 ft. 2 in. (3.1m) — was set in the middle of Hangzhou Bay by an ICE V360 tandem vibratory pile driver.
The company began its participation on the job by performing a casing drivability analysis and study with contractors, including Second China Harbour Engineering Group, based in Wuhan, Guangdong Changda Highway Engineering Company of Guangzhou, and Second China Road and Bridge Group headquartered in Xian. ICE subsequently supplied three sets of its V360 vibratory hammers to Second China Harbour Engineering Group and Guangdong Changda Highway Engineering Company, the two main contractors building the spans and towers over the water.
“The construction of the foundations underneath each pier of the Hangzhou Bay Bridge is probably the most difficult task in building the entire 36-kilometer [22.4 mi] bridge.” noted Walter Tang, regional manager of ICE China, based in Shanghai. “There are two types of pile for the foundation. Bridge sections with shorter spans and lower elevations are supported by thousands of 1.6-meter [5.2 ft.] diameter steel pipe piles up to nearly 90 meter [295 ft]. long, while sections with longer spans including the major north and south waterway towers are supported by massive bored piles with 2.8 meter [9.2 ft.] diameter, drilled 120-meters [394 ft.] into the seabed.”
“A bored pile is first drilled by a reverse circulation drill rig and then cast at the spot with steel cage and high strength concrete. Domestic manufacturers, including Zhongsheng based in Nanjing, carried out this work,” he continued.
“In order to install the bored piles for each pier, a working off-shore platform almost the size of a football field must be built in the middle of the sea. Each platform is responsible for constructing 38 bored piles. Before each bored pile is drilled, a steel casing 3.1 meters [10.2 ft.] in diameter, 42 to 60 meters [138 to 197 ft.] long, and weighing from 60 to 80 metric tons [66 to 88 tons], must be driven into the seabed. Rather than the conventional impact method of piling, due to the magnitude of the casing size, all the casings are driven by ICE V360 hydraulic vibro hammers.”
Convertible into two individual driver/extractors or for underwater use as necessary, the V360T features twin 1,050-hp (783 kW) Caterpillar 3412E-DITA Tier I engines, which among other features diagnose mechanical problems and adjusts operating conditions such as air/fuel ratio and speed in order to stay abreast of changing conditions.
“With clamping to the casing, V360 vibro hammers generate up to 1,500 vpms [vibration per minute] of high frequency vibration with sufficient amplitude, causing the seabed soil to become liquefied,” Tang explained. “With the centrifugal force from the hammer, plus the weight of the hammer and casing, the casing is driven to the designed elevation.
“Driven under high-frequency vibration, the casing maintains verticality deviation of less than 1:600, ensuring the quality of the bored piles, the safety of the process, and that drilling will go smoothly. With the casings in place, the possibility of ground collapse and contamination of the bored piles is prevented.”
These casings will remain as permanent members of the bored piles. However, the piles used to support the working platforms will be extracted by the V360 hammers and re-used for other purposes. International Construction Equipment also is responsible for equipment commissioning, operation training, and after-sale services.
New Source of Funding
The bridge project has broken ground in another way, as it represents the first infrastructure approved by the Chinese State Council for private investment. Much of the capital has been provided by enterprises based in the province, while most of the balance is being provided through bank loans and bond issues. Unusually for China, the government will have a relatively small amount invested in the job.
The largest private stockholder in the project is Hangzhou-based Songcheng Group, which contributed $86 million. According to a June 2003 interview in the Shanghai Star, Huang Qiaoling, president of the group, its interest in investing in the project was largely due to the fact it is the largest tourist-related private business group in China, and the bridge will provide and increase promotion of the bay and local attractions. Songcheng Group has been building theme parks for the past 10 years or so and has four in the area, including American City, which are already being visited by four million tourists annually.
The Hangzhou Bay area is under heavy development, with an industrial area being built in Jiaxing, north of the bridge site. Plans also are afoot for developing Shanghai as an international deep-sea port, while other large-scale projects being undertaken on both sides of the bay involve the chemical industry as well as steel and car manufacturing. CEG