Khun Tan Tunnel

Khun Tan Tunnel is Thailand's longest railway tunnel, measuring 1,352.10 meters, located on the border of Lamphun and Lampang provinces within Doi Khun Tan National Park in Mae Tha District, Lamphun. Constructed between 1907 and 1918 during the reign of King Rama VI to connect the Northern Line through the Khun Tan mountain range, it was engineered under German engineer Emil Eisenhofer. The tunnel remains in active use and is notable for its historical engineering and scenic mountain setting.

Visitors can expect to see the historic brick-lined portals of Thailand's longest railway tunnel set in forested mountains of Doi Khun Tan National Park. The tunnel is still active on the Northern Railway Line between Khun Tan Station in Lamphun and Mae Tan Noi Station in Lampang. Visitors can view the northern and southern portals, watch trains enter and exit, explore the adjacent Khun Tan Railway Station area, take photos of the mountain landscape, and walk short forest trails nearby.

Constructed between 1907 and 1918 during the reign of King Rama VI as part of the Northern Line extension to Chiang Mai. Directed by German engineer Emil Eisenhofer, it was built with manual labor and took 11 years to complete. At 1,352.10 meters it remains the longest railway tunnel in Thailand and represents a major early 20th-century engineering achievement.

Recognized as an important engineering landmark and symbol of the Northern Railway. The tunnel and nearby Khun Tan Station are valued for their heritage and association with the development of rail transport linking Bangkok to northern Thailand, and are a focal point for visitors to Doi Khun Tan National Park.