The State Railway of Thailand (SRT) has updated the construction progress of the northern double-track railway section “Den Chai–Chiang Rai–Chiang Khong,” launching a new phase moving forward as planned. Civil engineering works have surpassed 50% completion. All contracts are being expedited with a target to open in 2028 to support transportation, tourism, and border trade, raising northern connectivity to the Mekong River basin.
According to reports from the State Railway of Thailand (SRT), the construction of the northern double-track railway from Den Chai to Chiang Rai to Chiang Khong covers a total distance of 323 kilometers with a construction budget of 72.835 billion baht. As of December 2025, the overall project progress stands at 50.496%, slightly behind schedule by 0.237% due to flooding impacts in the northern region. However, this delay remains manageable, and the goal to open service in 2028 remains on track.
The project is divided into three construction contracts: Contract 1 covers Den Chai to Ngao, spanning 103 km with a budget of 26.56 billion baht, currently 47.618% complete but behind schedule by 7.406% due to flood impacts and complex terrain requiring multiple structural and track works. The SRT is closely monitoring and accelerating work. Contract 2 covers Ngao to Chiang Rai, 132 km with a budget of 26.89 billion baht, with progress at 56.726%, ahead of schedule by 4.136%. Contract 3 covers Chiang Rai to Chiang Khong, 87 km with a budget of 19.385 billion baht, progress at 45.798%, ahead by 3.52%. This last section is vital for linking rail systems to border areas to support future transport and cross-border trade.
Regarding the tunnel excavation, a key component of the project: 1. The two tunnels in Phrae Province, totaling 1,059 meters, are 55.95% complete. 2. The Ngao tunnel in Lampang Province, 6,211 meters long—the longest railway tunnel in Thailand—is 69.30% complete. 3. The Mae Ka tunnel in Phayao Province, 2,700 meters long, is 69.25% complete. 4. The Doi Luang tunnel in Chiang Rai Province, 3,400 meters long, is 64.79% complete. All tunnels are progressing as planned. Currently, three of the four tunnels have achieved breakthrough (tunnel boring completion), with only the Ngao tunnel scheduled to be completed on 12 Dec 2026.
The SRT reported that although some contracts experienced slight delays from the original schedule, overall project progress exceeding 50%, combined with continuous acceleration efforts across all contracts, maintains confidence that the Den Chai–Chiang Rai–Chiang Khong railway project will be completed and operational by 2028 as planned.
The Den Chai–Chiang Rai–Chiang Khong double-track railway is a key strategic infrastructure development for the country’s transportation network. Starting at Den Chai Station in Phrae Province, it will traverse 59 subdistricts across 17 districts in four provinces: Phrae, Lampang, Phayao, and Chiang Rai. Upon completion, it will enhance travel efficiency for passengers and freight, reducing travel time by approximately 1 to 1.5 hours compared to road transport.
Additionally, this route serves as a crucial link connecting northern Thailand to the Thai-Lao border and the Greater Mekong Subregion, facilitating cross-border trade and cargo transfer to Laem Chabang port. It will help reduce overall national logistics costs. The railway route is also notable for its scenic natural landscapes, passing through mountain ranges, bridges, and numerous tunnels, which will promote tourism and generate income for communities along the line. This aligns with the government’s policy to develop infrastructure to sustainably drive the country’s long-term economic growth.
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