Comprehensive Implementation of the MRT Blue Line Extension in Bangkok

The Blue Line Extension marks a major step in expanding Bangkok’s rapid transit capacity, transforming earlier planning work into full‑scale implementation. Spanning 27 kilometres with both underground and elevated sections, the project enhances cross‑city connectivity, improves access to key urban districts and supports more efficient, sustainable mobility for millions of daily commuters. Five major contractors were engaged to deliver the complex civil works, including challenging tunnelling operations beneath Chinatown and the Chao Phraya River.

Dorsch had previously contributed to the planning of this line as part of the Three Lines Project in 2005. The current project represents the full implementation of the Blue Line Extension, covering a total length of 27 kilometres with 19 stations. The alignment comprises both underground and elevated sections, including technically demanding tunnel works beneath Chinatown and the Chao Phraya River.

Five Contractors were awarded the execution of works with a total Value of 1.4 Billion Euro. Italian-Thai Development is constructing the first package, to design and build the 2.8-kilometre underground route from Hua Lamphong to Sanam Chai including two underground stations, worth Bt11.441 billion. Ch Karnchang is constructing the second package, to design and build the 2.6km underground route including two underground stations from Sanam Chai to Tha Phra worth Bt10.687 billion. The joint venture between Sino-hydro Corporation and Unique Engineering and Construction won the third package, involving the construction of the 11km Tao Poon to Tha Phraelevated rail line worth Bt11.284 billion. Sino-Thai won the fourth contract, involving construction of a 10.5km elevated railway from Tha Phra to Lak Song, worth Bt13.334 billion. Ch Karnchang will supply the trackwork system, worth Bt10.687 billion.

The Bang Sue -Tha Phra Section (so called "Circle Line") starts from Bang Sue Station, passing along Pracharat Sai 2 Road. It crosses over the Chao Praya River turns left along Charansanitwong Road until it reaches Tha Phra at Petch Kasem and Charansanitwong intersection. The length is 13.1 km with 8 elevated stations.

The Hua Lamphong – Lak Song Section starts at Hua Lamphong Station, goes underground along Charoen Krung Road, passes under China Town, Wang Burapha, and then turns left at Sanam Chai Road (Wat Poh) before crossing under the Chao Phraya River at Pak Khlong Talat.

The route continues under Khlong Bangkok Yai, it finally enters Petch Kasem Road and ends at Lak Song. The 4 underground stations end at Itsaraphap and the route becomes elevated for 7 stations. The length is 15. 9 km. with 7 elevated stations and 4 underground stations.