Construction work on the double-track railway between Map Kabao Station (Saraburi) and Thanon Chira Junction (Nakhon Ratchasima) includes three tunnels. The one through Dong Phaya Yen mountain range will be the longest tunnel in Thailand.
TUNNEL 1: Between Map Kabao Station, Pha Sadet Station and Hin Lap Station. It is a double tunnel, single track, and 5.20 kilometers long. Width 7.50 meters, height 8.50 meters. This will be the longest in Thailand once completed at the end of 2022.
TUNNEL 2: The second tunnel is 256 meters long and between Hin Lap Station and the new Muak Lek Station which will become a new landmark for tourists. It is a single tunnel with double tracks. Width 11 meters, height 9.45 meters.
TUNNEL 3: The third tunnel is between Khlong Khanan Chit Station and Khlong Phai Station. It is a double tunnel with single track in each tunnel. Length is 1.20 kilometers, width 7.50 meters, height 8.50 meters.