Chiang Mai Highway 121 is to adopt “Elevated Road Model No. 5” in hopes of finding a permanent traffic solution to help cut traffic by over 50%
Earlier today, the Ministry of Transport held a meeting to present the results of the selection of development options for Highway No. 121, Don Kaew–Mueang Kaew section. The meeting was attended by high-level executives and representatives from government agencies, the private sector, and affected communities.
The meeting was chaired by Siwanat Buabong, Deputy Governor of Chiang Mai, to gather public opinions and finalise the most suitable development model. The main objectives are to improve travel efficiency along the project route and minimise impacts on the public (e.g., guard posts, fences, buildings), especially in densely populated areas, and to ensure the design fits current traffic conditions.
Model No. 5 Considered the Most Promising Option
The consulting group told the meeting that since March 2025 the Department of Highways has instructed the consultants to collect public feedback and develop six design models for the elevated road.
The study found that Model No. 5 is the most attractive option because it requires the least amount of land for expropriation, and has the lowest environmental and ecological impacts. In terms of traffic efficiency, this model can reduce congestion by more than 50%. However, Model No. 5 has a notable drawback: it may obstruct the scenic view of Doi Suthep, an issue that must be seriously considered.
The total investment for Model No. 5 is estimated at approximately 2 billion baht, consisting of:
- 1 billion baht for construction,
- 500 million baht for land expropriation,
- 500 million baht for other operating expenses.
The overall execution is expected to take about 2.5 years. The Department of Highways may conduct several more public hearings to ensure a well-rounded conclusion before detailed design begins, which will clarify the exact areas requiring expropriation.
Route Improvement Plan Divided Into 3 Sections
The improvement of Highway 121 (Don Kaew Intersection – Samoeng Intersection), covering approximately 20.857 km, is divided into three sections:
Section 1: Km 32+900 – Km 39+200
(Entry to the 3rd Army Region – Chiang Mai International Convention and Exhibition Centre)
- Improve intersections to match traffic volume
- Focus on major problem intersections: 14 key points + 6 minor intersections
- Some intersections may be closed due to the short spacing (500–550 m) to improve travel efficiency
Section 2: Km 39+200 – Km 42+730
(Jet Yod–Chang Khian Intersection to Iron King Intersection)
- Use a Separate Drive system to divide main and local traffic
- Reduce conflict points
- Improve intersection layouts
- Redesign median openings to suit traffic demand, particularly near Huay Kaew Road and Suthep Road, areas with hotels, buildings, and commercial zones
Section 3: Km 42+730 – Km 51+019
(Suthep Municipality Intersection – Phuechkasem Intersection)
- Improve intersections with dedicated left/right-turn lanes
- Upgrade traffic signals to match traffic volumes
- Includes the Tunnel Intersection and Phuechkasem (Ratchaphruek) Intersection
Environmental and Impact Studies
The project will include:
- Collection of baseline data
- An Initial Environmental Examination (IEE)
- A full Environmental Impact Assessment (EIA)
These assessments cover four areas:
- Physical environmental resources
- Biological environmental resources
- Human use values
- Quality-of-life values
