CHIANG RAI, THAILAND – A new double-track railway from Den Chai to Chiang Rai and Chiang Khong was set to become a key northern transport corridor, linking Thailand’s rail network directly to the border at Chiang Khong by 2028.
Strategic link across four northern provinces
The planned line stretched about 323.1 kilometers from Den Chai district in Phrae province to the border district of Chiang Khong in Chiang Rai province. It ran through 59 subdistricts in 17 districts across the four northern provinces of Phrae, Lampang, Phayao and Chiang Rai, designed to support growing transit and cross-border trade within the Greater Mekong Subregion.
Part of national rail expansion and tourism push
The State Railway of Thailand (SRT) classified the project under its “Intercity Rail Network Development, Phase 3” programme to increase long-distance capacity. In addition to its freight role, the new route with what would become the country’s longest rail tunnel was explicitly planned as a new tourism corridor in the North.
26 stations and universal design
Along the alignment, 26 stations were to be built, including four major stations, nine minor stations and 13 halts. Facilities were planned under universal-design principles and supplemented with continuous safety fencing along the tracks to separate the line from surrounding areas.
Bridges, underpasses and removal of level crossings
The project included rail bridges, 40 road bridges over the tracks and 102 road underpasses beneath the line. Additional feeder roads, overpasses, walkways and motorcycle crossings were intended to replace or secure a total of 254 level crossings, enabling higher speeds for both passenger and freight services.
Freight yards and border logistics hub
For freight operations, four transshipment yards were planned along the line, together with a container storage and loading yard at Chiang Khong station. This terminal was to be built on 150 rai of land and connected by road directly to the Chiang Khong border checkpoint to streamline cross-border cargo movements.
Record-breaking tunnel as centerpiece
According to the SRT, the project would include the longest railway tunnel in Thailand, whose exact designation had not yet been finalized. In total, four tunnels were to be constructed, described as critical for continuous double-track operations and the targeted increase in operating speeds.
Tunnel construction: mixed pace across provinces
For Tunnel 2 in Phrae province, with a length of 1,059 meters, construction progress stood at 60.24%, which was 23.06 percentage points below the planned 83.30%. The Ngao Tunnel in Lampang province, measuring 6,211 meters, recorded 72.52% completion, 1.72 percentage points ahead of the plan of 70.80%.
Advances in Phayao and Chiang Rai tunnels
The Mae Ka Tunnel in Phayao province, at 2,700 meters, reached 71.53% progress, exceeding its target of 64.02% by 7.51 percentage points. The Doi Luang Tunnel in Chiang Rai province, 3,400 meters long, achieved 67.17% completion, or 9.75 percentage points more than the planned 57.42%.
Overall line slightly behind schedule
As of January 2026, overall construction progress on the Den Chai–Chiang Rai–Chiang Khong double track stood at 53.421%, just 0.220 percentage points below the planned 53.641%. Contract Section 1 from Den Chai to Ngao reached 51.530%, falling 6.919 percentage points short of plan, while Contract Section 2 from Ngao to Chiang Rai at 58.857% and Contract Section 3 from Chiang Rai to Chiang Khong at 48.473% were 3.837 and 3.331 percentage points ahead of schedule respectively.