Trimble RTK GPS In Use on Hangzhou Bay Bridge Project
Real time kinematic GPS systems will be used to position more than 7000 pilings that will comprise the 22.5-mile-long (36 kilometer) Hangzhou Bay Bridge
A sample installation of a Trimble 5700 RTK system. More than 50 units are in place along the path of the proposed bridge to position the pile drivers.
Pictured at the Sutong Yangtze Bridge project are, from left, Zhang Weihao, Walter Tang, (manager of China ICE in Shanghai), Zhang Guoquan, and Lin Qingye. China Harbour Engineering used the vibratory pile driver on the Sutong project before moving it i
China Harbour and ICE employees prepare one of the tandem V360T vibratory pile drivers on 2nd China Harbour's barge in Hangzhou Bay.
A crane lifts the V360T.
The unit is in place on the casing.
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 111,111-square-foot. (10,000-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 45,000 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 5,200-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. Edit Module