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

Phuket is preparing for its most significant infrastructure leap in over a decade. The Kathu-Patong Expressway project, which includes a tunnel cutting through the island's central mountain range, has reached its final approval stage. A decision from Thailand's Cabinet is expected in Q4 2026.

For anyone who owns property or is considering a purchase in the Kathu and Patong areas, this is a first-order signal. Transport connectivity directly shapes property valuations, and this project has the potential to reshape demand across the entire west coast of the island.

Key Facts

• Thailand's Cabinet decision on the Kathu-Patong Expressway is expected in Q4 2026.

• Deputy Transport Minister Sornpetch Bunyamanee personally inspected progress during a visit to Phuket in late June 2026.

• The project is overseen by the Expressway Authority of Thailand (EXAT), the state agency responsible for the country's toll road network, including Bangkok's expressways.

• If approved, construction could begin promptly and is expected to take about four years, according to The Phuket Express.

• The route addresses a chronic bottleneck on the only road over Patong Hill, where a 5 kilometer stretch can take 40 to 60 minutes during peak hours.

• EXAT is reportedly studying preliminary toll rates to keep costs manageable for households: hypothetically 10 baht for motorcycles, 20 baht for cars, and 40 baht for trucks.

• Phuket is simultaneously advancing a deep-sea port project, signaling a broader government strategy to modernize the island's transport infrastructure.

Story and Context

The idea of a tunnel connecting Kathu and Patong has been debated on Phuket for more than 15 years. Early feasibility studies date back to the early 2010s, but the project was repeatedly delayed by budget constraints, environmental reviews, and changes in government.

The core problem is straightforward. Patong is Phuket's largest tourism and commercial hub, generating a substantial share of the island's income. Yet reaching it from the eastern side of the island means navigating a single winding mountain road over the pass. Anyone who has driven from the airport or Phuket Town to Patong during rush hour knows the gridlock: motorbikes weaving between buses, taxis honking, and the entire traffic flow squeezed into two lanes of hairpin turns.

This has concrete consequences for the property market. Kathu, located on the other side of the ridge, has historically been seen as an 'inland' district, less appealing for short-term rental investors. Condominiums there are priced, on average, 25 to 35 percent lower than comparable units in Patong, according to market estimates. A separate market analysis suggests the tunnel could cut travel time on this bottleneck route from roughly 40 minutes to about 10 minutes, effectively integrating central Phuket with both coasts and unlocking Kathu's potential as a practical, more affordable commuter hub for workers, expats and long-term residents alike.

Context from other infrastructure projects matters too. Phuket is simultaneously working on a deep-sea port and discussing a future light rail line. According to The Phuket Express, Deputy Transport Minister Sornpetch Bunyamanee reviewed progress on several projects during a single visit in June 2026. This is not a coincidence but part of a broader strategy: the government is trying to transform Phuket from a seasonal resort destination into a year-round international hub.

For international buyers, one detail deserves particular attention. EXAT is the same authority that manages Bangkok's toll expressway network, and its model relies on toll collection. This means the Kathu-Patong tunnel will most likely charge a fee, similar to routes like the Don Muang Tollway in the capital. Preliminary hypothetical figures floated by planners suggest rates as low as 10 baht for motorcycles and 20 baht for cars, though final tolls will depend on further studies.

There are risks worth noting. The Cabinet has not yet granted final approval, and Q4 2026 is a target review date, not a guarantee. Thailand's infrastructure history includes projects that were approved and then revised or stalled during the tendering phase. Still, the level of political attention, including personal site visits from a deputy minister, suggests serious intent behind this one.

Timing also matters for investors. Even after Cabinet approval, construction of a project this size typically takes about four years. Buying property ahead of the tunnel makes sense before the market fully prices in the news, but investors should not expect immediate capital appreciation. This is a play with a realistic horizon of 2029 to 2031, once the tunnel is actually operational.

For context on the surrounding market, Kathu currently has roughly 268 active listings, with condominiums making up the majority (149 of 268) and a median asking price near 4.9 million THB, ranging from 1.39 million to 58 million THB for larger villa plots. Foreign buyers can purchase condominiums under Thailand's standard 49 percent foreign quota per building, while villas and houses are typically structured through 30-year leasehold arrangements.

Source: The Phuket Express

Ready to invest in Thailand? Our experts will help you find the perfect property.

FAQ

When will the final decision on the Kathu-Patong tunnel be made?

Thailand's Cabinet is expected to review the project in Q4 2026. This is a scheduled review date, not an automatic approval.

Who is building the expressway?

The project is managed by the Expressway Authority of Thailand (EXAT), the state agency that operates the country's toll road network, including Bangkok's expressways.

Will the tunnel be a toll road?

Most likely, yes. EXAT operates on a toll model, and planners have floated preliminary hypothetical rates of around 10 baht for motorcycles, 20 baht for cars, and 40 baht for trucks.

How will the tunnel affect property prices in Kathu?

Kathu currently trades at roughly 25 to 35 percent below Patong, according to market estimates. Cutting the commute from 40-60 minutes down to a fraction of that time is expected to narrow this gap, particularly for properties suited to short-term rentals.

What other infrastructure projects are underway on Phuket?

A deep-sea port project is progressing in parallel, and a light rail line is under discussion. The Deputy Transport Minister reviewed several projects during a single visit in June 2026.

When will the tunnel actually open?

Even with approval in 2026, construction of a project this scale in Thailand typically takes about four years. A realistic completion window is 2029 to 2031.

Should I buy property in Kathu right now?

The optimal strategy is entering before final approval, ahead of the market fully pricing in the news. This is a long-term position though, with capital appreciation likely materializing only after the tunnel actually opens.

What is the current traffic situation between Kathu and Patong?

The only route runs over a mountain pass. During peak hours, the 5 kilometer stretch can take 40 to 60 minutes due to chronic congestion.