State Railway of Thailand sounding out public on proposed Dark Red Line from Wongwian Yai (Bangkok) to Maha Chai (Samut Sakhon)
The State Railway of Thailand (SRT) has begun collecting public input on the proposed Dark Red Line commuter rail extension from Wongwian Yai in Bangkok to Maha Chai in Samut Sakhon.
It is a long-planned project aimed at modernising the historical Mae Klong railway and improving connectivity between Bangkok and its suburbs.
Speaking at the first public hearing, organised recently, SRT chief engineer for special projects and construction, Atthapol Kaoprasert, discussed updated details of the feasibility review, environmental impact assessment (EIA), preliminary engineering designs and draft tender documents.
The project is being revisited from earlier studies conducted in 2006 by the Office of Transport and Traffic Policy and Planning (OTP), which examined five possible alignments linking the Taksin transport hub and the Maha Chai area, he said.
Option 1 proposes an underground section from Hua Lamphong to Wongwian Yai, passing under the Chao Phraya River near River City mall, intersecting with the Gold Line and then continuing on an elevated track along Lat Ya Road.
From there, the route would follow the existing Mae Klong railway corridor through dense commercial districts including Talat Phlu and Samre, crossing Ratchadaphisek Road and Rama II Road before heading to Maha Chai in Samut Sakhon’s Muang district. The total length is 37.3km.
He said Option 2 mirrors Option 1 through Wongwian Yai but remains on a straighter alignment past kilometre 32, avoiding Rama II Road and instead continuing directly to Ban Khom Station and the Maha Chai depot, ending at the original Maha Chai station. The length is 35.9km.
Option 3 maintains a similar underground stretch to Wongwian Yai but adjusts the final section to bypass dense residential zones and avoid the elevated roadway over Rama II. The alignment would shift towards Ekachai Road, where vacant land allows for easier construction and future development. The length is 36.8km, he said.
Option 4 follows the same general approach as Option 3, but modifies the curve approaching Ekachai Road to provide a wider radius, enabling higher operating speeds for trains. The length is 36.6km.
Option 5 diverges from the other alignments shortly after Khlong San on the west bank of the Chao Phraya River, veering directly onto Ekachai Road from kilometre 8.7 and staying on this corridor through to the proposed new Maha Chai Station.
This alignment reflects the Mass Rapid Transit Master Plan Phase 2, a key blueprint for future rail expansion in Greater Bangkok. The length is 36.3km.
Mr Atthapol said the public hearings aim to ensure all stakeholders understand the project’s objectives, environmental study process and development timeline.
After all comments are collated, the SRT expects to finalise the preferred route and submit the project for cabinet approval around 2027, with construction tentatively planned to begin in 2028, he said.
Source: https://www.bangkokpost.com/thailand/general/3149289/srt-sounding-out-public-on-proposed-dark-red-line
