The Quanzhou Bay cross-sea bridge, a key control project for China's first cross-sea high speed railway completed its ballastless track construction on July 4. The cross-sea railway bridge, with its basic structure completed in December 2021, spans more than 20 kilometers across the bay. The quality of the ballastless track is the key to ensuring the safety and stability of train operation. In order to ensure construction accuracy, the engineering team independently developed and applied the new double-block ballastless track linear control construction method. The Fuzhou-Xiamen high-speed railway, with a length of 277 kilometers and a speed of 350 km per hour, is expected to be the first cross-sea railway for bullet trains in China.