Design of Phuket Kathu-Patong Tunnel Revised to Reduce Construction Risks; Total Investment Remains 11 Billion Baht, Toll Cut to 20 Baht

Reported by Thai Chinese News on June 25, Phiphat Ratchakitprakarn, Deputy Prime Minister and Minister of Transport, disclosed that Thailand plans to raise safety standards for major infrastructure projects. The designed diameter of the Kathu-Patong Tunnel will be adjusted from 17 meters to 14 meters to cut construction risks. The total investment budget will remain unchanged at 11 billion Thai baht. The project is expected to be submitted to the Cabinet within this year, with construction kicking off next year, opening to traffic in 2031, and toll fees lowered to 20 baht.

 

Phiphat shared the latest progress of the landmark Kathu-Patong Tunnel project in Phuket at the opening ceremony of the 15th Academic Symposium on Tunnel Construction and Maintenance Technology. Once completed, it will be the largest tunnel project in Thailand’s history.

 

The tunnel was originally designed with a diameter of 17 meters. Following an engineering risk assessment, the Ministry of Transport resolved to reduce the diameter to 14 meters to boost structural stability and simplify construction procedures. Extra width will be reserved inside the tunnel to safely accommodate cars and motorcycles, which account for over 65% of all vehicles in Phuket.

 

Phiphat added that global surges in oil prices and construction materials have pushed up overall construction costs by roughly 8%. Nevertheless, downsizing the tunnel diameter from 17 meters to 14 meters will offset part of the cost hikes, keeping the total project expenditure steady at approximately 11 billion baht with no additional budget required.

 

Land acquisition work is progressing smoothly and is set to reach full completion by September this year. Meanwhile, Phase 2 of the scheme — a route linking Kathu to Phuket International Airport — can be advanced in parallel.

 

Phiphat noted that all relevant agencies have delivered solid cooperation, as all parties recognize the urgent need to resolve Phuket’s chronic traffic woes. If the project secures Cabinet approval this year, construction can commence next year and commercial operation will start in 2031.

 

Upon completion, the tunnel will offer residents and tourists an alternative travel route connecting Phuket Airport to key tourist hotspots, most notably Patong Beach. The travel time will be shortened to merely 20 to 30 minutes, drastically easing severe congestion on the province’s main arterial roads.

 

Surachet, Director General of the Expressway Authority of Thailand (EXAT), commented on the submission timeline for project documents to the Ministry of Transport and the Cabinet. The original target was June, yet supplementary paperwork preparation has delayed the handover to July. He expressed confidence that subsequent review procedures will not drag on for long.

 

In line with the government’s policy to slash toll charges and ease residents’ living expenses, EXAT has proposed cutting toll fees for four-wheeled vehicles from around 40 baht to 20 baht per trip, with a discounted rate of 10 baht per trip available during certain time windows to deliver tangible benefits to the public. While this adjustment will lower project revenue, the financial impact remains manageable.

 

The Phase 2 development plan is scheduled to be submitted to the Cabinet for review next year to align with the overall construction schedule. The construction period for Phase 1 will last around four years, and Phase 2 roughly three years, allowing both sections to enter service nearly simultaneously.

 

Initial traffic projections indicate that Phase 1 will handle roughly 70,000 vehicles per day upon opening. Once both phases are fully operational, daily traffic volume will exceed 100,000 vehicles, highlighting the project’s critical role in mitigating traffic congestion and fuelling Phuket’s economic and tourism expansion in the long run.