Thailand’s longest railway tunnel nears completion, opening planned for 2028

LAMPANG – Construction of Thailand’s longest railway tunnel, stretching 6.2 kilometres through northern Thailand’s mountainous terrain, is nearing completion, with excavation expected to finish in December and train services scheduled to begin in 2028.

Deputy Prime Minister and Transport Minister Phiphat Ratchakitprakarn presided over a tunnel breakthrough ceremony for the Ngao Tunnel in Ngao district, Lampang province, on Wednesday (11 November).

The 6,215-metre tunnel forms part of the Den Chai–Chiang Rai–Chiang Khong railway project. Excavation began on 22 December 2023, with just 24.30 metres remaining.

Phiphat described the milestone as a significant achievement for Thailand’s railway infrastructure, highlighting the engineering challenges of tunnelling through mountainous terrain with complex geological conditions.

State Railway of Thailand (SRT) Governor Anan Phonimdaeng said construction required specialised techniques and strict safety supervision due to the varying rock formations, including limestone and volcanic ash deposits dating back hundreds of millions of years.

Once excavation is completed in December, work will continue on the tunnel’s internal structures, railway systems and safety equipment, followed by inspections and testing.

The railway is expected to open in 2028, improving passenger connectivity and freight transport in northern Thailand.