Muhamad Abidin, 49, a vehicle dispatcher at the HSR project's concrete mixing station, hopes the project can be completed soon so he can visit his daughter in Jakarta more often.

Though the distance between Jakarta and Bandung is only around 150 km, it can take between three and six hours by car due to traffic congestion. With a maximum speed of 350 km/h, the high-speed link will shorten the travel time between the two cities to about 40 minutes.

"I barely go to Jakarta to see my daughter because the round trip can cost me a whole day, so I only get to see her when she comes back home during holidays," said Muhamad. "When the HSR project is completed, I can go to see her during weekends, which is very convenient."

In the future, Muhamad plans to use his China Railway Group earnings to buy a villa on his home island of Sumatra. "I hope the villa has a nice sea view, and it will be well-decorated and big enough for my whole family," he said.

Confident about completing the project on time, China Railway Group's Zhang said the impact of the HSR line in Indonesia is profound. "As a business-to-business project, the cooperation demonstrates how companies can be the main carrier to promote the Belt and Road Initiative on an economic level," he said.

"We are also open to anyone who is interested in HSR to come and learn (about the project)," said Zhang.

Just outside the Walini Tunnel, an exhibition hall was established to provide information and showcase key technologies used in the Jakarta-Bandung HSR project. More than 1,000 Indonesia students from local universities have visited so far.

"My family and friends are happy that I can have the opportunity to join this massive project in Indonesia," said technician Tinambunan.

"What I have learned here is very helpful for my future career. I am willing to share my experience with others. I am grateful for what my Chinese colleague has taught me," he said, adding that he often goes shopping, watches movies and eats out with his Chinese mentor. "We see each other every day, and now we are just like brothers," he said.