The signing of contract sections 4-5 for Thailand’s first high-speed rail line, linking Bangkok and Nakhon Ratchasima, faces delays after Boonchai Panich (1979) Co Ltd requested to extend its original bid price of 10.3 billion baht until 16 July 2025, citing unresolved internal discussions.
Boonchai Panich (1979) Co Ltd, the selected contractor for section 4-5 of the Thai-Chinese high-speed rail project, has requested to maintain its initial bid price of 10.325 billion baht through 16 July 2025. This request comes after its original bid validity expired on 30 June 2025. The section in question covers a 13.3-kilometer stretch between Ban Pho and Phra Kaew in the first phase of the 253-kilometer line between Bangkok and Nakhon Ratchasima.
According to a statement received by the State Railway of Thailand (SRT), the company is still in discussions with its board on several key issues, including rising construction costs. The SRT has completed all necessary documents to finalize the contract and is prepared to issue a notice to proceed (NTP) immediately upon the company’s confirmation.
However, the SRT cannot compel the company to sign. If the firm remains non-committal closer to the new deadline, the agency will follow up before deciding on the next steps. Should Boonchai Panich ultimately withdraw, the project would require a new bidding process, potentially delaying the timeline by at least six to seven months—or longer in case of formal complaints—while driving up overall costs.
Separately, the Ayutthaya station design, a key concern due to its proximity to a UNESCO World Heritage site, is undergoing further revisions. Changes have included reducing the structure’s height from 37.45 meters to 28 meters and ensuring a 2.5-meter gap between the new high-speed station and the existing rail structure. These adjustments follow recommendations from ICOMOS, an advisory body to UNESCO.
Although the station’s design is not yet finalized, the SRT may proceed with the track construction under the current contract and issue a second NTP once station plans are approved. The agency aims to complete section 4-5 within three years.
The Thai-Chinese high-speed rail project, which began in late 2017 and consists of 14 contracts, remains only 45.64% complete as of 25 June 2025—lagging behind schedule by 18.55%. While two contracts are finished and ten are under construction, two remain pending. These include section 4-5 and section 4-1 (Bang Sue–Don Mueang), which is awaiting modifications due to overlapping infrastructure with another rail project. The SRT now targets full operation by 2029.
Officials and stakeholders involved in the project include SRT leadership, board members of Boonchai Panich (1979) Co Ltd, and representatives from the Fine Arts Department and ICOMOS.