A top government official has said the structure of the artificial islands constructed for the HK$120 billion Hong Kong-Zhuhai-Macao Bridge are safe.
Photos and videos shared last week of an island just west of Hong Kong’s border sparked concerns that breakwater components had become disconnected from the main structure. Another artificial island closer to the Macau side – connected by an underwater tunnel – also showed a similar scattered arrangement of concrete blocks.
Director of Highways Daniel Chung visited Zhuhai on Sunday to meet with the bridge’s managing authority and inspect the project, but he did not speak to media until Monday evening: “The breakwater design is scientific, reasonable and safe. The breakwater components have not been washed away by waves.”
The Zhuhai-based authority managing the section, which was constructed by the mainland side, claimed that the components were deliberately designed to be placed randomly underwater. But the bridge’s design documents showed that the blocks should be placed higher to cover the perimeter wall of the island.
But Chung said the breakwater construction matched with the final 2014 design: “There is no sign the breakwater washed away.”
“We do not foresee any change of the design, as it functions properly,” he said.
Chung said the dispersed blocks also served another purpose in that that vessels will not mistakenly cross over the tunnel and damage the structure: “We can’t see any problem with it.”
He said the design determined that there should be fewer dolos blocks – each weighing five tonnes – above the tunnel, in order not to affect its structure.
He also said there was no sign of movement, cracks, or water seepage inside the underwater tunnel, after he examined it on Sunday.
Chung said the breakwater did not move apart even after severe typhoon Hato hit the city last August: “We should have confidence in this project.”
He said that the Hong Kong side will be notified if there are important issues surrounding the bridge. He said the three sides regularly meet each month to discuss the issues.
The authority’s deputy director Yu Lie said on Sunday that the waves on the artificial island’s western side were weaker than on the southern side, thus the western side did not need a packed arrangement of breakwater dolos blocks.
“We put them randomly at fixed locations, the blocks are interlocked – we did not place them completely randomly,” Yu said. “We have a tunnel below, so that the weight above cannot be too heavy, thus we have to adopt such a special treatment.”
“It is the not the case that it would collapse or sink if we fail to fully cover [the edge of the island],” he said.
“Hong Kong may have Hong Kong’s way of doing it, but we have our way of doing it. We followed rules and standards – we cannot just place them randomly for such a huge bridge.”
But veteran civil engineer Ngai Hok-yan said the arrangement was much thinner and the blocks were much lighter than Hong Kong’s design under the same environment. He said he was therefore concerned whether they were providing enough protection against Pacific Ocean waves.
“It is a fact that they were not arranged well, thus we have our concerns, and we hope that [the Authority] can give us confidence,” he told an RTHK radio programme on Monday.
So Yiu-kwan, another experienced civil and structural engineer, said Yu was “not willing to admit a mistake.”
He said that, if the current arrangement was in the original design, then the design must be problematic, as dolos blocks should be interlocked and cannot involve space in-between.
“I don’t care if they are done by Chinese or by Hong Kong people – stones are stones, they react to the natural patten. If there is a leak, regardless of whether it is done by Chinese or foreigners or Hongkongers, the result will be the same,” he said on a Commercial Radio programme on Monday.
