International Dredging Review

International Dredging Review
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China Railway Bridge Bureau Group Co. Ltd. is using Trimble 5700 GPS systems for precise positioning of pilings and bridge sections on the Hangzhou Bay Bridge under construction in Zhejiang Province China.

The 22.5-mile-long (36 kilometer) bridge will connect the north and south shores of the bay shortening the drive from Shanghai to Ningbo to 179 kilometers – a reduction of 120 kilometers. The crossing will connect Zhapu City on the north shore of the bay with Cixi City on the south shore.

China Railway Bridge Co. is the prime contractor on the project which will be completed in 2008. It will be the longest transoceanic bridge in the world and the second longest bridge of any type. The Lake Pontchartrain Causeway in Louisiana holds the record as the world’s longest bridge.

Approximately 50 Trimble 5700 RTK (real time kinematic) systems have been set up at sites where the bridge will span the bay. Three Trimble 5700 CORS GPS systems are used as reference stations to provide the RTK corrections required for precise measurements of the project.

Additional 5700 systems are located on barges providing millimeter accuracy for the real-time positioning of piles casings and pre-fabricated sections of the bridge. The latter is accomplished by moving sections of the bridge on barges for precision placement using GPS for position and orientation. The Trimble 5700 RTK systems are also used for measuring the coastal topographic details as well as hydrographic surveys of the seabed. Using Trimble equipment across the entire construction site enables all surveying mapping and construction activities to share one geodetic reference system.

The main span of the new bridge will use the cable-stayed design.

Two of the subcontractors driving the pilings and casings are 2nd China Harbour Group and Guangdong Changda Highway Engineering Co. Both are using V360T vibratory pile drivers from International Construction Equipment Inc. (ICE). China Harbour’s two V360’s were first used at Sutong Yangtze Bridge before being moved into Hangzhou Bay. Changda purchased a V360T specifically for this project.

Walter Tang is manager of ICE China in Shanghai who sold the units to the contractors.

|!|During the first few weeks we have technical persons with each unit|!| said Tang. |!|After the contractor becomes familiar with the machine we leave the jobsite giving the contractor full control of the operation. If there are any problems we are only 90 minutes away in our Shanghai office|!| he said.

On July 10 2004 the first 3.1 m (10 foot two-inch) diameter steel casing was driven by an ICE V360 tandem vibratory pile driver into the ground at the middle of Hangzhou Bay near Eastern China Sea.

There will be more than 7000 piles on this project – 3.1 meter 2.4 meter and 1.8 meter diameter drilled piles with steel casings plus 1.5 or 1.6-meter-diameter driven steel pipe piles. They are being driven 40 meters into bottom material which consists of bay mud to fine sand and cohesive clay with N value up to 35.

Other equipment being used are impact hammers including IHC S-280 Juttan HHK20S and diesel hammers D128 D150 and D160.

The six-lane bridge includes an 111111-square-foot. (10000-square-meter) service platform in Cixi which will have a tower for viewing the area’s the Qiantang River Bore known locally as the Silver Dragon a tidal wave that gathers momentum in the Gulf of Hangzhou and surges through the mouth of the Qiangtang River racing up the river at a height of up to 30 feet and a speed of more than 15 miles per hour. The bore occurs on the first through fifth day of each lunar month and is celebrated by thousands at the Quingtang River Festival each August.
The bridge has a designed life span of 100 years and daily traffic volume is expected to reach 45000 vehicles in the first year of operation.

The price tag on the bridge is 11.8 billion Yuan (US$1.42 billion). Seventeen private enterprises from Zhejiang province will invest 50.25 percent of the total funds needed to build the bridge with the remainder coming from bank loans and bond issues and a small investment from China’s central government.

The Hangzhou Bay bridge is the largest project of the planned 5200-kilometer-long national highway that runs through China from Tongjiang in northeast China’s Heilongjiang Province to Sanya in south China’s Hainan Province.

Following completion of the the Hangzhou Bay bridge a number of sea-crossing bridges at the Bohai Bay Huangdao in Shandong Province and East China Sea will be constructed involving more than 100 billion Yuan (US$12.09 billion).

|!|It (the Hangzhou Bay bridge) will certainly enable each part of the delta to develop much closer relations with one another and greatly enhance the area’s overall economic growth” said Zhejiang Governor Lu Zushan.

Editor’s note: Thanks to Walter Tang of China ICE who provided technical information on the bridge and vibratory pile drivers for this article.