Chongqing- From the windowless and rattling old trains with a top speed of 60 km/h to the Fuxing train with air conditioning and soft sofas that can cruise at an operational speed of 350km/h, China's railways have never stopped achieving surprising transformations.

"Thumbs up to all those who worked hard for this high-speed rail," said Zhou Dingxiang, the general design manager of the Chongqing and Hubei section of the Zhengzhou-Chongqing High-speed Railway project of the CREEC (Chongqing) Survey, Design and Research Co. Ltd. "A group of the best people made the 'hardest road.'"

The Zhengzhou-Chongqing High-speed Railway line was put into operation on June 20 with the railway starting from Zhengzhou of Henan Province in the north and ends in Southwest China's Chongqing Municipality, passing through Henan, Hubei, and Chongqing.

Among them, the Chongqing North to Wanzhou North Section was opened in 2016, and the Zhengzhou East to Xiangyang East Section was opened in 2019. This time, the Xiangyang East to Wanzhou North Section was fully opened.

According to Zhou, the design and construction of the Xiangyang East to Wanzhou North section is the most difficult. The mountains along the route are high and deep, and the terrain is complex and changeable.

Furthermore, geological disasters such as karst and landslides occur frequently, with high environmental protection and water conservation requirements. From 2009 till now, Zhou has been leading his team to work hard on the front line of the Chongqing and Hubei section.

Ecologically sensitive areas

How to overcome the challenging design and construction of this section?

Zhou said the terrain of this high-speed rail line is undulating with unfavorable geology. Thus, the team reduces the risk of railway construction and operation from the design source.

Facing the high requirements for ecological and environmental protection, the line avoids fragile ecologically sensitive areas, where the dumping field is concentrated in site selection. At the same time, the project design plan adopts greening and reclamation measures to minimize high fill and deep excavation so that the high-speed rail is highly integrated with the natural environment.

Terrain reconnaissance

"There are hundreds of people in the project design team, and many stories happened during the terrain reconnaissance and design process," said Zhou.

When the team went to the site to explore the geological and landform of the Lesser Three Gorges tunnel passing through the canyon section of the Zhongling River in April 2016, they experienced something truly unforgettable.

They walked along the winding cliffs, a bottomless gorge on one side and a topless cliff on the other, and everyone dared to look ahead. Rain poured in the mountain when the trip was less than halfway, making the road more difficult.

"On the way, some of my colleagues were stabbed by plants, some tripped, and my left knee's meniscus injury recurred," said Zhou. "But in the end, we all reached the design centerline."

This terrain reconnaissance provided substantial support for the decision-making of the following route design scheme of the Lesser Three Gorges Tunne.

As the longest 350km/h single-hole and double-track high-speed rail in Asia, the Three Gorges Tunnel also serves as a national ClassⅠhigh-risk tunnel completed 7.5 months ahead of schedule and has been highly recognized in the industry.

"Zhengzhou-Chongqing High-speed Railway is the first high-speed rail that runs through the Three Gorges Reservoir area," said Xiao Qiang, deputy chief engineer of CREEC (Chongqing) Survey, Design and Research Co. Ltd, executive deputy chief designer of Zhengzhou-Chongqing High-speed Railway. "For every designer and builder involved, they have emotions and different feelings."