The Pha Sadet Tunnel is the longest double-track railway tunnel in Thailand, stretching over 5.4 kilometers on the Northeastern line between Map Kabao and Hin Lap stations in Saraburi Province. It officially opened on July 28, 2024. This engineering marvel was built to significantly reduce travel time and enhance safety while crossing the Dong Phaya Yen mountains, replacing the original winding and steep tracks. Designed with modern technology as a single-track twin tunnel, it features advanced ventilation systems and emergency evacuation routes every 500 meters, marking a major milestone in Thai railway development that connects the central region to the Northeast more efficiently than ever before.