Meticulous work

In September 2006, work on constructing subway lines began throughout Xi'an, and at the end of last year, the city had eight such routes in operation.

Construction of subway and light rail lines has made commuting much easier for Xi'an residents. However, as more buildings have been built along the lines, archaeological work has been impeded to a certain extent.

"Excavation is actually a sort of 'destruction'," Zhang said. "The sites of ruins are buried 1.5 meters to 1.8 meters below ground, and tombs and cultural relics have often been uncovered during construction and subway engineering projects in Xi'an.

"We sometimes do analysis and scientific research onsite, but our principle is to minimize the amount of excavation."

In 2018, the archaeological team found the main road in ancient Xianyang, with Xu naming it Empire Avenue.

Excavations determined that the road was more than 50 meters wide and had many wagon ruts in its center.

"After measuring them meticulously, we found that one of the tracks was 1.35 meters wide. Measuring it was painstaking work, as we had to compare the ruts very carefully and pair them one by one," Xu said.

Three such avenues have been found by the team, and they form the main part of the road network in the northern area of ancient Xianyang, she added.

"For we archaeologists, this network is a framework for the city. As we cannot find the ancient city wall, there is no way of determining how large Xianyang was. We can only be guided by the road network."

Standing on the platform just over 11 meters above the No 6 palace site, Zhang pointed to a straight asphalt road.

"Nowadays, our road engineers' thoughts overlap with those of the ancients, with the roads in Xixian New Area built along the avenues of the Qin Dynasty. However, we still don't know when the roads of the Qin Dynasty will be unearthed and revealed to the world," he said.