Thai-Chinese Railway stuck in the mud: Contract 3-5 redesign for the Khok Kruat–Ban Mai section adds 2 billion baht, but the contractor refuses to accept the price. Contract expires 18 July 2026; penalty waiver negotiations expected. Another 3–4 contracts are also set to require additional construction budgets, estimated at 3.7 billion baht in total. Meanwhile, the rolling-stock systems Contract 2.3, worth 50 billion baht, expired in April 2026, yet the site has still not been handed over. The Chinese side has proposed a cost increase and a 45-month extension.
A news report from the Ministry of Transport disclosed that the Thai-Chinese High-Speed Railway Project, Phase 1 — the Bangkok–Nakhon Ratchasima section spanning 250.77 kilometres (km) and valued at 179,412.21 million baht — has been under construction since 21 December 2017. The civil works comprise a total of 14 contracts: 2 have been completed, 10 are currently under construction, and 2 are in the procurement process. As of July 2026, overall progress stands at 55%, which is still 33% behind schedule. Civil works construction is expected to be completed in 2030, and the Ministry of Transport has now set a target of opening the Bangkok–Nakhon Ratchasima section for service within 2030.
The report stated that, beyond Contract 4-1 covering the Bang Sue–Don Mueang section (15.21 km) — which overlaps with the High-Speed Rail Link to the three airports and whose solution is for the State Railway of Thailand (SRT) to take over and carry out the construction itself — and Contract 4-5 covering the Ban Pho–Phra Kaeo section (13.30 km, valued at 10,325.90 million baht), which is currently in the process of expediting various steps toward a new bidding round and is expected to begin construction soon, there are additional construction problems that require urgent resolution.
There are currently two more significant contracts that, in addition to requiring construction timeline extensions, also require increases in the contract value. The first is Contract 3-5, the Khok Kruat–Nakhon Ratchasima section, spanning 12.38 km, valued at 7,750 million baht, with SPTK Joint Venture Co., Ltd. (comprising Napa Construction Co., Ltd., Teamsecartar SDN BHD, and Bina Puri SDN BHD) as the contractor. Construction currently stands at only 18% complete, more than 81% behind schedule.
The key obstacle is that the site was handed over to the contractor later than stipulated, due to 60 rental building units obstructing construction — which have since been demolished and removed — as well as complaints from local residents in the area. These factors necessitated a design revision: changing the original design from an embankment (raised earthwork) 4–5 metres high to an elevated structure for the Khok Kruat–Ban Mai section, a distance of approximately 7.85 km. This requires an additional 2,052.08 million baht in construction costs and results in a 36-month extension of the construction period.
The report indicated that SRT is currently in negotiations with the contractor to proceed with construction according to the revised design under the increased budget first, after which the matter will be submitted to the Cabinet for approval to adjust the budget framework, and the additional works will then be formalised as a Variation Order (VO) to the contract. Most recently, the contractor has refused to accept the price of 2,052.08 million baht, citing current cost conditions that make it impossible to proceed at that figure, and it is expected that the construction budget will need to be increased further.
Contract 3-5 for the Khok Kruat–Nakhon Ratchasima section was signed on 26 November 2020, with construction scheduled to begin on 26 January 2021, and a contract end date of 10 January 2024. The contractor has been granted COVID-relief measures with a 0% penalty rate until 18 July 2026. The contract is now technically expired, but the matters of design revision, budget increase, and timeline extension have not yet been resolved. As for penalty charges, negotiations for a waiver may continue.
In addition, there are Contract 3-2 (the Mueang Mak and Lam Takhong Tunnel section, 12.23 km, with Nawarat Patanakarn Public Co., Ltd. as contractor, valued at 4,279 million baht), Contract 3-3 (the Bandai Ma–Lam Takhong section, 21.60 km, with Thai Engineering and Industry Co., Ltd. as contractor, valued at 9,838 million baht), Contract 3-4 (the Lam Takhong–Si Khio and Kut Chik–Khok Kruat section, 37.45 km, with ITD as contractor, valued at 9,848 million baht), and Contract 4-7 (the Saraburi–Kaeng Khoi section, 12.99 km, with Civil Engineering Co., Ltd. as contractor, valued at 8,560 million baht) — all of which are currently under consideration for additional construction budget increases, with the combined total estimated at no less than 3,700 million baht.
There is also the matter of Contract 2.3 — covering track systems, electrical and mechanical systems, as well as the procurement of rolling stock and personnel training — valued at 50,633.5 million baht, with China Railway International Co., Ltd. and China Railway Design Corporation, both Chinese state enterprises, as the contractors. The contract was signed on 28 October 2020 with an execution period of 64 months, and expired on 22 April 2026. Progress currently stands at only 1.270%.
The problem with Contract 2.3 is that SRT has been unable to issue a Notice to Proceed (NTP) and hand over the site, because civil works construction remains behind schedule. As a result, the Chinese side has proposed extending the construction period under Contract 2.3 by a further 45 months, with completion projected for January 2030. Most recently, China has also proposed an increase in the contract fee, leaving negotiations unresolved. The contract has already expired, and SRT is currently in negotiations with the Chinese side on both the timeline extension and the waiver of penalties, on the grounds that the delay is not the fault of the contractor.
