An aerial drone photo taken on May 27, 2025 shows the portal to a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

This photo taken on May 27, 2025 shows the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

Staff members work at the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province, May 27, 2025. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

An aerial drone photo taken on May 27, 2025 shows an ongoing renovation project of a railway linking Suifenhe and China's border with Russia next to an existing rail line in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

Staff members work at the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province, May 27, 2025. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

This photo taken on May 28, 2025 shows the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

Staff members and workers pose for a group photo at the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province, May 28, 2025. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

An aerial drone photo taken on May 27, 2025 shows an ongoing renovation project of a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

This photo taken on May 28, 2025 shows the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)

This photo taken on May 28, 2025 shows the construction site of a tunnel along a railway linking Suifenhe and China's border with Russia in Suifenhe, northeast China's Heilongjiang Province. Construction of this 602-meter railway tunnel started last May and was completed on Wednesday. The new tunnel will significantly boost line capacity of a railway linking Suifenhe and the China-Russia border, which is under renovation with a designed speed of 120 kilometers per hour. (Xinhua/Wang Song)