Lin Ming, chief engineer and general manager for the islands and tunnel project of the bridge, delivers a lecture to colleagues. XINHUA 

The Hong Kong-Zhuhai-Macao Bridge, scheduled to open on Wednesday, has changed the appearance of the Pearl River Estuary. However, one of the most talked about aspects of the bridge is hidden below the waterline.

The bridge involves a 6.7-kilometer immersed tunnel, the longest in the world for road traffic and the first offshore structure of its kind in China. It has been described as the most difficult part of the construction of the bridge, which, at a total length of 55 kilometers, is the world's longest sea-spanning structure.

Throughout the construction process, the international community questioned how Chinese engineers could manage such a huge project.

However, during more than a decade working on the project, Lin Ming, chief tunnel engineer, never doubted his team's ability.

"China's civil engineering sector should never be satisfied with quantity or scale. It must earn global respect through devotion to perfection in every detail," he told China Daily in an exclusive interview.

Lin, who is also chief engineer at China Communications Construction Co, joined the project in late 2005. Following a feasibility study, the relevant government departments decided that the HZMB had to include an immersed tunnel, and placed overall responsibility in Lin's hands.

Design decisions  

A bold design was required to provide room for major shipping lanes, and a traditional cable-stayed bridge was ruled out because the towers would be so high they would disrupt the approach of planes to the nearby Hong Kong International Airport.

Complex geological conditions underwater also had to be taken into account because the bed of the delta consists of unstable ooze rather than solid rock, meaning some traditional engineering options had to be abandoned.

Thus an offshore immersed tunnel was the only solution, and the design incorporated two artificial islands to connect the bridge with the tunnel.

Before the tunnel was completed at the end of last year, only a few offshore immersed tunnels longer than 3 km had ever been built - the Oresund Link between Denmark and Sweden, the Busan-Geoje Fixed Link in South Korea, the Chesapeake Bay Bridge-Tunnel and the San Francisco Yerba Buena Island Tunnel in the US.

Moreover, only a few countries had mastered key technologies for immersed tunnels. "We were eager to cooperate with foreign experts," Lin said.

However, as expensive consultation fees would put the project over budget, innovation became the only way forward, but it brought unforeseen pressures. "Can you imagine working on a project when you have no previous experience to rely on?" Lin said.

In addition, Chinese engineering's reputation rested on the team's success, so the work became more than just a job - it became a duty.

During the process, Lin's team mastered key technologies for immersed tunnel construction. It also made significant improvements and devised several innovations, which contributed to faster construction times, lower costs and most important, reduced safety risks.

To build the tunnel weighing millions of metric tons about 50 meters below the surface of the water, the team collaborated with other Chinese companies to employ gigantic tailor-made equipment.

None of the new technologies came easily, Lin said: "We faced tremendous pressures and risks every day. On this project, 3,000 people walked a tightrope, and meeting the challenge was a test of our power and ability to innovate."

Road to perfection  

Though proud of what his team has achieved, Lin concedes that there is still a gap between engineering in China and some other countries, and it will only be closed by innovation and attention to detail.

"You have to view it in a rational way. It's about the advancement of your craft, method, processes and knowledge. Innovation is also a kind of technology. China has entered an era in which it needs to innovate, and is capable of doing so," he said.

Further opening-up and exchanges will also be vital.

Lin gave credit to every foreign expert who contributed to the project, saying he learned a lot whenever he exchanged ideas with them.

While he hailed China's achievements in civil engineering over the past 40 years, he acknowledged that some people in the international engineering community still don't hold "built by China" in the highest regard.

"Foreign experts are fastidious about whether your product has enough advanced technology. It's about your attitude to detail and whether your product is user-friendly and convenient," he said.

"Our goal is very simple and clear - every brick needs to be the finest."

Future goals  

He added that more exchanges will help other countries understand China's development.

"By opening up further, we can let other countries understand our level of development - seeing what we can do and how we do it," he said.

"We have an ingrained cultural barrier with other countries that we have to break through. Otherwise, it will become a bottleneck to the Belt and Road Initiative.

"As time goes by, I believe we will become as skilled as advanced countries (with regard to civil engineering), and that's when we will make our foray into the international market." (China Daily)