Kathu-Patong Tunnel: What Phuket's Biggest Infrastructure Project Means for Property Investors

Phuket is preparing for its largest infrastructure undertaking in a decade. The Kathu-Patong Expressway project, featuring a tunnel through the island's central mountain ridge, has reached its final approval stage, with Thailand's Cabinet set to review it in Q4 2026. For anyone who owns property in Kathu or Patong, or is considering buying there, this development carries concrete financial implications.

Deputy Transport Minister Sornphet Bunyamanee confirmed the timeline during a personal site inspection on the island, calling the project a government priority. This is the first time the tunnel plan has advanced this far after being discussed for more than 15 years.

Key Facts

• Cabinet review date: Q4 2026, marking the first time the project has reached this stage of approval.

• Phase one covers construction of the Kathu-Patong Expressway, including a tunnel through the mountain ridge separating the two districts.

• Construction timeline: once approved, building is expected to begin shortly after and take approximately 4 years to complete.

• Work is progressing in parallel on related infrastructure, including a proposed Phuket deep-sea port.

• Political backing comes from both local Phuket authorities and national transport agencies.

• Current travel time between Kathu and Patong via the Patong Hill mountain pass ranges from 25 to 50 minutes depending on traffic. The tunnel would cut this to just 5 to 10 minutes.

• The project is viewed as a cornerstone for improving connectivity across Phuket's entire west coast.

Story and Context

The idea of a tunnel linking Kathu and Patong is not new. It has been discussed on the island for more than 15 years, with every incoming government promising action, only for budget constraints, environmental review, and political turbulence to stall progress each time.

So why might this be the moment it finally moves forward? Three factors have converged. First, record tourist arrivals: Phuket welcomed more than 10 million international visitors in 2025, and the island's infrastructure is straining under the load. The single mountain road connecting the eastern side of the island (home to the airport and business districts) with the western beaches (Patong, Kamala, Karon) has become a chronic bottleneck.

Second, the deep-sea port. The government sees Phuket as a hub for cruise tourism and cargo shipping, but a port is meaningless without a functioning road network to support it. The Kathu-Patong Expressway would link these two ambitions into a single transport chain, and it is being developed alongside another route, the Muang Mai-Ko Kaeo-Kathu expressway, aimed at connecting the northern entrance of the island, Ko Kaeo, and Kathu, districts historically seen as overlooked working areas compared to the glamorous west coast.

Third, and perhaps most decisive for investors, is real estate money. Phuket is in the middle of a construction boom. Kathu, until recently regarded as the island's backwater, is now being rapidly developed with condominiums and villas. Land prices there have climbed 30-40% over the past three years. A tunnel would transform Kathu from a pass-through zone into a fully fledged residential district just five minutes from the island's main beach strip.

For property investors, this is a textbook 'buy the rumor' situation. Properties in Kathu and upper Patong currently trade at a significant discount to beachfront real estate. If the tunnel gains Cabinet approval and construction begins, that price gap is likely to narrow. Meanwhile, the broader west coast, including Bang Tao, Layan, Kamala, and Cherng Talay, continues to see strong demand from wealthy overseas buyers, with villas outperforming condos as buyers prioritize lifestyle and long-term value, according to Knight Frank Thailand's outlook for the luxury segment through 2026.

It is worth keeping Southeast Asia's typical pace in mind. Major infrastructure projects in Thailand move slowly. Cabinet approval is only the beginning; tenders, contractor selection, and environmental assessments follow. A realistic start date for construction is 2027-2028, with completion of phase one unlikely before 2030-2031. But property markets rarely wait for concrete. They react to expectations.

There is a useful parallel with Bangkok, where every new extension of the BTS and MRT lines pushed prices along future station corridors up by 15-25% before a single rail was laid. On an island market like Phuket, where land supply is physically constrained, that effect could be even more pronounced.

If you are planning a trip to Phuket to view properties, it is worth driving the route from the airport through Kathu to Patong yourself. Only then does it become clear exactly what problem this tunnel solves, and why it matters so much for the west coast's future.

Source: The Phuket Express

FAQ

When will construction on the Kathu-Patong tunnel start?

Thailand's Cabinet will review the project in Q4 2026. Tender procedures follow approval, with a realistic construction start date of 2027-2028 and an estimated four-year build.

How will the tunnel affect property prices in Kathu?

Based on comparable infrastructure projects in Bangkok, transport upgrades have historically lifted nearby property prices by 15-25% even before construction finished. Kathu currently trades at a notable discount to Patong's beachfront locations.

What is the current road situation between Kathu and Patong?

The only route runs over the Patong Hill mountain pass, with travel times of 25-50 minutes depending on traffic. The tunnel would reduce this to 5-10 minutes.

Could the project be delayed again?

That risk exists. The tunnel has been discussed for more than 15 years. However, 2026 marks the first time it has reached Cabinet review, and the Deputy Transport Minister has personally confirmed its priority status.

What else is being built on Phuket besides the tunnel?

A deep-sea port and the Muang Mai-Ko Kaeo-Kathu expressway are being developed in parallel, all part of a broader plan to improve the island's connectivity.

Which area of Phuket stands to benefit most from the tunnel?

Kathu and eastern Patong are expected to see the biggest impact, with Kathu shifting from a transit zone into a full residential district with fast access to the west coast.

Is now a good time to buy property in Kathu?

That depends on your investment horizon. Buyers willing to hold for 3-5 years may find current Kathu prices attractive, though project delay risk should be factored in.

How is the tunnel connected to the deep-sea port project?

Both are viewed as components of a single Phuket transport network, with the Kathu-Patong Expressway providing the port's link to the island's west coast.

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