A construction site of a tunnel of Sichuan-Tibet Railway File photo: IC

The construction of the Bayu Tunnel from Lhasa to the Nyingchi railway section of the strategic Sichuan-Tibet Railway has been completed, media reports said on Sunday, a development that one expert called a big step to strengthen connections between China and South Asia.

According to the People's Daily, construction of the 13,073-meter Bayu Tunnel, which faced a lot of difficulties given its complex geographical conditions was successfully completed on Sunday.

In June, China announced it would start work on the 1,700-kilometer Sichuan-Tibet Railway, a project anticipated to take seven years and cost 216.6 billion yuan ($30.78 billion).

The Lhasa to Nyingchi section is the second phase of the Sichuan-Tibet Railway, the second strategic railway network in Southwest China's Tibet Autonomous Region. This section is expected to be completed in 2021.

Trains on the line operating at standard speed will only take 13 hours to travel from Chengdu, Southwest China's Sichuan Province to Lhasa. High-speed trains will only take eight hours, saving nearly 28 hours compared with taking the Qinghai-Tibet railway and nearly three days compared with the Sichuan-Tibet Highway to Lhasa, according to reports.

The Sichuan-Tibet Railway will also be connected to Tibet's Yadong Port and Nielamu Port, which are China's two important land gates to India and Nepal.

The Sichuan-Tibet Railway will boost Tibet's economic development in areas such as tourism and border trade, as well as China's connectivity with South Asia -- and even the security of the region, an expert said.

"It will promote the economic development of the border area with India and Nepal, because, in market size and the amount of products, Tibet is relatively low. Once it is connected to Sichuan, which ranked No.6 in GDP among China's provincial-level regions in 2018, it will have huge potential," Tian Yun, director of the China Society of Macroeconomics Research Center, told the Global Times.

"The market size of Sichuan compared with the border area is much bigger. The new rail service will shorten the distance and travel time between Sichuan and the border area, and it will have a huge lifting impact on the border trade," Tian said.

Besides the impact on economic development, Tian noted that Tibet's security could also be strengthened.

According to Tian, in the past, due to the harsh geographical environment, it was extremely difficult to provide logistics services.

"When the railway is completed, it will be easier to ensure the security of the Tibet Autonomous Region by logistics from Sichuan," Tian said.