According to a report by the Highways Department Seven massive piles for construction of the Hong Kong-Zhuhai-Macau Bridge will have to be rebuilt, with the cost borne out by the contractor.
One pile is said to be located at the artificial island for immigration clearance, and goes 70 meters into the ground. Rebuilding each pile will cost more than HK$1 million.
The department did not give a reason for the rebuilding, either disclose the location of the piles, or the contractor that was responsible, although confirmed remedies with costs borne by the contractor have to be under taken on seven piles out of the more than 1,000 of the bridge project.
With a spokesperson for the department saying engineers from the department conducted thorough on-site checks on all piles of the construction to determine if they complied with the contractual standards.
If the piles are found to violate the standards due to problems with quality of material or construction progress, the contractor will generally suggest bearing the cost of the remedies, such as building extra piles near the substandard pile, or building a new pile to replace it.
The remedies will be carried out according to the mechanism in the contract, after obtaining approval, and under close supervision of consulting engineers and relevant on-site construction staff.
Former president of the Hong Kong Institution of Engineers, Greg Wong Chak-yan, was quoted as saying ‘the impact of rebuilding the piles on construction progress depends on whether the piles are among those in the last phase of construction and what remedies are needed Rebuilding a new pile is the last resort. Extra piles may be added near the piles involved to support the bridge. The former can take a month, while the latter can be completed within two to three weeks,”.
As checks are usually conducted simultaneously with the construction, the influence on construction progress is minimal if the seven piles are not in the last lot to be completed, he said.
“There is no perfect workmanship, and it is all down to the percentage involved. The situation is not unsatisfactory, with seven out of more than 1,000 piles needing rebuilding, accounting for less than 1 percent.” Wong said.
He stated that there are three possibilities behind rebuilding, namely, beehive structure inside piles caused by trapping of air or water in concrete, mud in between the connection points, and standard of the rock beneath the pile are below expectations.
Wong also added that geoexploration for construction of infrastructure at sea is much more difficult than on land, and could cost three times as much.
Seven Piles on Hong Kong-Zhuhai-Macau Bridge to be rebuilt