Department Director-General Phichit Hunsiri said work is currently underway on the underpass, retaining walls, box culverts and temporary bypass roads around the four-way junction. Contractors have been instructed to increase watering frequency at the site to control dust and minimise impact on nearby residents. Completion is expected by 2027.
Highway 108 is the main route linking Chiang Mai city to the province’s southern districts including Hang Dong, Sanpatong, Chom Thong, Hod and Mae Sariang, continuing on to Mae Hong Son. While most of the route runs 4-6 lanes wide, it narrows to just 2 lanes through urban sections in Hang Dong, Sanpatong and the Ban Thung Siao community, where dense development leaves no room for widening, resulting in heavy congestion on this key tourist route.
The interchange will function as a bypass, diverting traffic away from these community areas and connecting to Highway 121 along the main irrigation canal, serving government offices, schools, commercial areas and canal-side residents before routing traffic south around the city centre. Once complete, it is expected to improve travel safety and speed, cut transport costs, and support tourism across Chiang Mai and Mae Hong Son.
The project includes a single underpass spanning 679 metres between kilometre markers 0+800 and 1+400, alongside a six-lane reinforced concrete road with 3-3.5 metre lanes and 1-2.5 metre shoulders, plus drainage, lighting and safety systems. Total budget: 1,246.285 million baht.
