USD 1bn Koh Samui bridge drilling begins

Seabed drilling has commenced for a geographical survey as part of the proposed THB 40bn (USD 1.17bn) Koh Samui bridge project, according to the local marine office in Koh Samui, south Thailand.

The survey aims to identify the optimal location for the bridge, which would connect Thailand’s second-largest island to mainland Surat Thani. The bridge will potentially span 37km, including 25km over the Gulf of Thailand.

Last July the Expressway Authority of Thailand (EXAT) revealed plans for the long-awaited Koh Samui infrastructure project to widen the current travel options via sea or air. The feasibility study and environmental impact assessment are expected to conclude by 2026, with construction beginning in 2029 and completion slated for 2033.

The drilling, expected to take 140 days, is a key step in evaluating the feasibility of the bridge, which would provide a 40-minute car journey across four lanes. EXAT governor Surachet Laophunsuk noted that public hearings to assess public interest are underway. The proposed toll for using the bridge is THB 700 (USD 20.50)m slightly cheaper than the TBH 760 (USD 20.25) ferry fee for vehicles, which also involves a longer travel time.

The project marks a significant step towards improving connectivity and economic integration between Koh Samui and the mainland, reducing dependence on ferry services and enhancing transport efficiency.

Project pending public approval

Originally planned for 2028, the bridge’s construction timeline was put back due to public hearing concerns, although the ongoing process of assessing public sentiment is expected by October 2026.

“The project will provide an alternative travel option between the mainland and Koh Samui, benefiting tourism and easing transport limitations,” EXAT governor Surachet Laophulsuk said. A bridge is far more cost-effective and environmentally friendly than a tunnel, he added.

To accommodate maritime traffic, the bridge will feature a combination of cable-stayed and beam bridge designs. The cable-stayed section will rise 50m above the channel, allowing passage for large ships such as oil tankers, ferries, and warships. The beam bridge section will stand 15m above mean sea level to facilitate fishing boats.

The structure will be built to withstand strong winds, earthquakes and collisions. With the bridge promising faster, more reliable travel, the EXAT says the project represents a transformative step for Koh Samui’s infrastructure, economy and tourism sectors.

The Thai Marine Office has meanwhile issued a notice cautioning boats navigating the designated survey zone from the lower part of Koh Samui district to Khanom district in Nakhon Si Thammarat. Buoys with lights have been placed to mark the boundaries, and vessels must maintain a 300m distance for safety.