CHIANG RAI – The State Railway of Thailand (SRT) is speeding up work on its new double-track railway projects. One of the key projects is the new Den Chai–Chiang Rai–Chiang Khong double-track line.
This route will support freight transport from the North to other regions and is expected to cut both logistics costs and travel time in the future.
A source from the Ministry of Transport shared an update on the Den Chai–Chiang Rai–Chiang Khong project. The new line is 323 kilometres long, with a construction budget of 72,835 million baht.
Construction is now underway and split into three contracts. Contractors began work on 15 February 2022 and are scheduled to finish on 14 January 2028, giving a total construction period of 71 months.
The SRT expects the line to open for service within 2028. The three construction contracts are as follows.
Contract 1: Den Chai–Ngao section
- Length: 103 kilometres
- Contract value: 26,560 million baht
- Construction progress: 45.746 percent, about 5.461 percent behind schedule
Land for construction has been handed over in 3,202 plots, equal to 98.22 percent of the required area. The contractor is ITD–Naowarat Joint Venture. Work started on 15 February 2022, and the contract runs until 4 January 2028.
Contract 2: Ngao–Chiang Rai section
- Length: 132 kilometres
- Contract value: 26,890 million baht
- Construction progress: 52.280 percent, about 4.147 percent ahead of schedule
Land handover has been completed for 3,417 plots, or 96.20 percent of the total. The contractor is CKST–DC2 Joint Venture. Construction began on 15 February 202,2, and the contract ends on 14 January 2028.
Contract 3: Chiang Rai–Chiang Khong section
- Length: 87 kilometres
- Contract value: 19,385 million baht
- Construction progress: 40.812 percent, around 3.222 percent ahead of schedule
Land has been delivered for 2,445 plots, equal to 97.92 percent of the total area. The contractor is CKST–DC3 Joint Venture. Work started on 15 February 2022 and will also finish on 14 January 2028.
Progress on land expropriation
The same source from the Ministry of Transport said that land expropriation and title arrangement along the full route covers a total of 9,661 rai.
There have been some hurdles. Errors were found in the information used in the contract documents, which delayed the Department of Lands in issuing the Ror Wor 9 documents.
To fix this, the SRT has held follow-up meetings with the survey teams from the Office of Survey Standards and Promotion (Soms) under the Department of Lands. The goal is to clear up the problems that have slowed down the issuing of the Ror Wor 9 documents.
Project consultants are now reviewing and correcting the inaccurate information in the contract documents so that it matches the actual situation on the ground.
If affected landowners are unhappy with the compensation offered for expropriation, they have the right to file an appeal.
Tunnel construction milestones
On 11 November 2025, Tunnel 2 in Song district, Phrae province, was successfully broken through. The tunnel is 1.059 kilometres long and is the first tunnel along this new double-track route. Construction of this tunnel is expected to finish by June 2027.
This breakthrough marks another step forward for the project, following earlier breakthroughs at Doi Luang Tunnel in Chiang Rai and Mae Ka Tunnel in Phayao. These three are now among the four tunnels that have been fully bored through.
Only the Ngao Tunnel remains. At 6.211 kilometres, it will be the longest railway tunnel in Thailand. The breakthrough for the Ngao Tunnel is expected in September 2026.
All tunnels on the line are designed as twin single-track tunnels (single-track tunnel in each bore). They are built to handle seismic activity, with structures that can resist earthquake vibrations. Each tunnel also has drainage systems to prevent flooding and cross-passage escape tunnels every 240 metres to support safety in the mountainous and monsoon-prone areas of the North.
Ngao Tunnel, as the longest railway tunnel in the country, is a highlight of the Den Chai–Chiang Rai–Chiang Khong double-track project.
Project overview: stations, tunnels, and freight facilities
The new Den Chai–Chiang Rai–Chiang Khong double-track line includes:
- 12 railway stations
- 13 halt stops
- 4 railway tunnels, with a combined length of 13.90 kilometres
- 5 container yards (CY), located at Den Chai, Phayao, Pa Daet, Chiang Rai, and Chiang Khong
The route starts at km 533+900 at Den Chai station in Phrae province and ends at km 857+000 in Chiang Khong district, Chiang Rai province.
