Questions remain over bridge safety

Fears over the almost-completed Hong Kong–Zhuhai–Macau bridge emerged after wave-absorbing protective blocks, known as dolosse or tetrapods, appear to have drifted away from the bridge’s artificial islands, leaving the sea tunnel threatened.

Aerial photographs last week showed two of the four artificial islands, which are managed by the mainland Chinese authority, had fewer tetrapods on one side, with some separated from the structure.

The bridge authority has explained that the tetrapods had been randomly placed on purpose in such a way—which differs from the Hong Kong authorities’ method—to get the best results, in view of the varying strength of waves.

“It is a special location, and we cannot place [the blocks] regularly in the usual manner above the water,” said deputy director Yu Lie. “The placement of the blocks under the water was by design and they were interlocked to perform the function of protecting the man-made island.”

The arrangement, he added, was also due to the tunnel underneath.

Yu also rejected claims of a cover-up, saying the governments of the three places were represented on the authority, and monthly meetings were held for the sides to discuss the project’s progress.

However, Hong Kong engineer Albert Lai Kwong-tak, who is also convenor of the Professional Commons think tank, urged the authority to make public the calculations and documents of the bridge design so that Hong Kong engineers could study the construction, according to The Standard.

“The most worrying point is that the authority had also admitted that the tetrapods would dislocate according to the design. They would need routine maintenance,” Lai said. “I won’t say this design is infeasible, but I would question whether it’s a good one.”

Hong Kong has so far committed to contributing about HKD10.7 billion (USD1.38 billion), or 43 per cent, of the main bridge’s construction cost. However, local officials will also end up spending another HKD110 billion to build the city’s connection to the main bridge. — Construction+ Online