From Tuesday, June 23 to Thursday, June 25, 2026, a "Site Visit & Technical Workshop" was held in Chaiyaphum Province and Nakhon Ratchasima Province, Thailand, as part of the preliminary study for the Highway No.225 Mountain Tunnel Construction Project, organized through cooperation between the Department of Highways (DOH) of Thailand and JICA (Japan International Cooperation Agency).

This program was attended by Teppei Tomita, Area Manager (AM) of Eight-Japan Engineering Consultants Inc. (EJEC), as a member of the JICA expert team. Through field inspections and technical exchanges, he contributed to advancing Thailand's road tunnel planning.

Thailand National Highway No. 225 is an important arterial road linking central and northeastern Thailand. The Khao Phang Hoei mountainous section in Chaiyaphum Province faces challenges such as steep terrain, landslide risk, and poor visibility. The Department of Highways has designated this section as a "sandbox project" and is advancing conceptual design and preliminary studies for a mountain tunnel solution.

This site visit was carried out jointly with JICA's technical expert team, led by a working group examining feasibility from geological, design, environmental, construction, and cost estimation perspectives.

The main components of the three-day site visit and technical exchange program were as follows.

As a member of the JICA expert team, Area Manager Tomita joined the site visit and technical workshop together with three other experts.

On site, the team examined the key topographical, geological, environmental, and construction-planning aspects of the mountainous section and held a technical briefing at the Chaiyaphum Highway District Office. They shared advanced Japanese expertise on engineering approaches, environmental considerations, and risk management. The team also visited the tunnel construction site for the Thailand-China High-Speed Rail Project (Khlong Phai-Lam Takhong section), gathering practical insights into design, construction, and project management from an active tunnel works.

This site visit and technical workshop provided a valuable opportunity to directly share Japan's advanced technology and experience as part of the preliminary study for the Highway No.225 mountain tunnel plan being promoted by the Department of Highways in cooperation with JICA. The JICA expert team, including Area Manager Tomita, made concrete recommendations from the perspectives of environmental consideration, safety, and construction technology, contributing to the enhancement of Thailand's technical capabilities and the sophistication of the project.