The 13.3-kilometre section between Ban Pho and Phra Kaeo—part of Phase 1 of the Thai-Chinese high-speed rail project from Bangkok to Nakhon Ratchasima—was initially awarded to Boonchai Panich with a bid of 10.325 billion baht. However, the firm’s commitment to the quoted price lapsed at the end of June without a formal response from its board.
The SRT had planned to sign the contract by June 2025, as previously approved by Thailand’s National Committee on World Heritage Convention, which confirmed that there were no objections to the construction design near historic Ayutthaya. A meeting with the Fine Arts Department was scheduled for 1 July to finalize design details, which must later be submitted to UNESCO.
Although the contract can legally be signed without waiting for final design approval, Boonchai Panich’s delay in reaffirming its bid poses a major obstacle. If the company fails to reconfirm its offer, the SRT will need to reopen the tender process—a procedure expected to take at least six to seven months and likely to result in higher construction costs.
Once the contract is signed, the SRT plans to issue a Notice to Proceed (NTP) for rail track construction. A second NTP will be issued later for Ayutthaya Station once its final design is approved. The project will retain its original site for the station, with adjusted plans to reduce the building height from 37.45 metres to 28 metres and maintain a 2.5-metre buffer from the historic station.
Design modifications also include less visually obstructive structures and more subdued colour schemes to minimize visual impact on the surrounding heritage landscape.
The SRT insists it is ready to proceed immediately if Boonchai Panich confirms its price, and views the delay as a normal part of internal corporate decision-making. The contractor was originally the third-ranked bidder. The top bidder, Italian-Thai Development PLC, declined to hold its price, and the second-ranked bidder failed to enter negotiations.
If no agreement is reached, construction of Section 4-5 could face significant delays, potentially affecting the revised service launch target for Phase 1 of the high-speed rail line, now set for 2029.