Get to know the MRT Purple Line project before the road collapses
The location of the road collapse on Wednesday (September 24) is an area currently under construction for the MRT Purple Line electric train project, which is part of the underground railway section.
The MRT Purple line electric train project, Tao Poon - Rat Burana (Kanchanaphisek Ring Road), held a contract signing ceremony between the Mass Rapid Transit Authority of Thailand (MRTA) and the construction contractors for civil works on March 11, 2022. The ceremony covered a total of six contracts valued at 82 billion baht.
Representatives from five construction companies involved in the contracts participated in the signing.
Additionally, an Integrity Pact was signed for the Purple Line project between the MRTA, the six contractors, and independent observers, ensuring transparency and fairness throughout the process.
Construction Progress and Timeline:
As of August 2025, the overall project construction is 61.80% complete. The MRTA has set a project timeline of 2,005 days for the completion of all six civil work contracts, starting from the notice to proceed (NTP) issued to the contractors.
The project commenced in 2022, with the expected opening for public use scheduled for 2027.
The area where the road subsidence occurred is under the construction of Vachira Hospital Station, part of the Purple Line project.
This section is part of Contract 1 for the design and construction of the tunnel and underground stations between Tao Poon and the National Library, with a budget of 19.43 billion baht.
This contract covers the design and construction of a 4.8-kilometre underground tunnel, with depths ranging from 16 to 35 metres.
The project includes three underground stations, two ventilation shafts between stations among other tasks.
The contractor for Contract 1 is CKST-PL Joint Venture.
Contract 2 involves the design and construction of the tunnel and underground stations from the National Library to Phan Fah, with a budget of 15.88 billion baht.
This contract covers the design and construction of a 2.4-kilometre underground tunnel with depths ranging from 23 to 46 metres, three underground stations, one ventilation shaft between stations and other tasks.
The contractor for Contract 2 is also the CKST-PL Joint Venture.
Contract 3 involves the design and construction of the tunnel and underground stations between Phan Fah and Memorial Bridge, with a budget of 15.109 billion baht. This contract includes the design and construction of a 3.1-kilometre underground railway tunnel with depths ranging from 22 to 41 metres, two underground stations, and three ventilation shafts between stations and other tasks.
The contractor for Contract 3 is ITD – NWR MRT Joint Venture, consisting of Italian-Thai Development Public Company Limited and Nawarat Patanakarn Public Company Limited.
Contract 4 involves the design and construction of the tunnel and underground stations between Memorial Bridge and Dao Khanong, with a budget of 14.982 billion baht.
This contract includes the design and construction of a 4.1-kilometre underground railway tunnel with depths ranging from 17 to 28 metres, two underground stations, and five ventilation shafts between stations and other tasks.
The contractor for Contract 4 is Unic Engineering and Construction Public Company Limited.
Contract 5 involves the construction of the elevated railway structure and stations between Dao Khanong and Kru Nai, including the Stabling Yard and Park & Ride facilities, with a budget of 13.094 billion baht.
This contract covers the construction of approximately 9 kilometres of elevated railway, seven elevated stations, four Park & Ride facilities located in Bang Pakok and Rat Burana, with a capacity of approximately 1,920 cars, and an electric vehicle parking building located near the Kanchanaphisek Ring Road.
The contractor for Contract 5 is Italian-Thai Development Public Company Limited.
Contract 6 involves the design and construction of the railway system along the entire project route, with a budget of 3.589 billion baht. This contract covers the design and construction of the railway system from Tao Poon to Kru Nai, which includes the railway system for the electric train and the internal railway system within the electric train parking facilities.
The work includes the installation of track rails, power supply rails, and other related tasks. The contractor for Contract 6 is also Italian-Thai Development Public Company Limited.
