Kathu-Patong Expressway 2026: 3.98 km Tunnel, 5-Minute Drive, 2031 Opening

The climb up Patong Hill in January looks like this: two lanes of switchbacks, a truck in first gear, forty cars and bikes stacked behind it, and forty minutes spent on a stretch that measures six kilometers on the map. The gravel emergency runoff on the descent is not there for decoration.

The Thai government now promises to replace this bottleneck with a toll road and tunnel that cuts the trip to five minutes. The timeline looks more concrete than it has in eight years: Cabinet submission in December 2026, construction start in October 2027, and opening of the first phase in 2031.

For investors, this means one thing. The entry window into land and property along the future route is open roughly until the first concrete is poured. After that, price will be set by the construction site, not by rumor.

Quick Answer

• The Kathu-Patong first phase is a toll road spanning about 3.98 km, of which roughly 1.85 km runs through a twin-bore tunnel under the mountain.

• Travel time between Kathu and Patong is projected to fall from 30-40 minutes in high season to about 5 minutes.

• Key dates: Cabinet approval - December 2026, construction start - October 2027, Phase 1 opening - 2031 (per EXAT and reported by The Thaiger).

• Estimated Phase 1 cost is around 14-15 billion baht, a figure revised several times since 2018 alongside land acquisition costs; one breakdown puts total project investment near 16.757 billion baht, including about 5.792 billion baht for land acquisition.

• Foreigners cannot own land directly in Thailand. Entry into land assets along the route means either long-term leasehold or a Thai company structure, and this legal layer is the real risk in the deal, not the construction schedule.

• Bottom line: only buy what already pays for itself through rental income today. The expressway should be a bonus, not a business plan.

Key Facts

• The project is led by the Expressway Authority of Thailand (EXAT), structured as a public-private partnership with toll collection; EXAT is reportedly seeking to raise about 20 billion baht through an infrastructure fund to finance Phase 1.

• Phase 1 connects Kathu district with Patong, bypassing the current Patong Hill switchback, one of the most accident-prone stretches of road on Phuket.

• Phase 2 would extend the route toward Phuket Town (Muang) and areas such as Koh Kaew, spanning several dozen kilometers with a substantially larger budget reported at roughly 67.5 billion baht; its timeline remains unconfirmed, though some reports suggest an October 2028 start.

• Toll rates have not been finalized as of early 2026. Previously discussed ranges are tied to vehicle type, from motorbikes to heavy trucks.

• The project has been on the agenda since 2017-2018. Construction start dates of 2020, 2022, and 2024 were all previously announced and all missed.

• A parallel island infrastructure project, the Tha Nun-Chalong light rail line, was shelved in 2021 and reworked into a tram/ART concept that, as of 2026, still has not broken ground.

What five minutes actually changes

Patong and Kathu currently function as two separate markets divided by a mountain. Patong runs on short-term rentals and nightlife economics, with new beachfront projects priced around 150,000-220,000 baht per square meter. Kathu houses the people who work the coast, along with schools, golf courses, and a hospital; new-build prices there run notably lower, in the range of 100,000-140,000 baht per square meter by market estimates.

The tunnel removes the barrier. Someone renting out a Patong unit to tourists could live in Kathu and stop losing an hour a day in transit. Hotel staff would no longer be tied to the expensive coastal strip. This is the classic transport-corridor effect: it is not the destination that gains value, but the area that time had cut off from it.

There is a flip side that land sellers rarely mention. A tolled entry into Patong will make traffic manageable, not free. Some local traffic will stay on the old road, and roadside retailers along the switchback are more likely to see falling footfall than a boost.

Why I would not recommend buying land 'for the expressway'

People who bought plots in Kathu back in 2018, banking on a 2024 opening, have paid eight years of land tax without a single baht of rental income. On Phuket, the infrastructure premium historically arrives not at the announcement stage, and not even at Cabinet approval, but in the final eighteen to twenty-four months before physical opening. Before that, the market prices in the probability of delay, and it is right to do so.

Then there is the legal layer. Land cannot be sold to foreigners outright. The remaining options are long-term leasehold registered with the Land Department (standard term of 30 years, with renewals not guaranteed by case law) or a Thai company structure where the foreign shareholder controls less than half the capital. The second route is regularly scrutinized for nominee shareholder arrangements. A land bet on a five-year horizon built on that structure is not an investment, it is a wager with poor terms.

If your budget is under 10 million baht, none of this applies to you: land plays in that range are not worthwhile, since fees and legal costs will eat the margin.

Where an entry point makes sense

A freehold condominium in Kathu, or on the eastern approaches to Patong, that already delivers 6-8% gross yield on long-term rental and does not depend on tourist seasonality. That kind of asset does not lose its logic if the Cabinet delays the project by a year, and it gains extra upside once the tunnel opens.

A second option, for those thinking on a ten-year horizon, is a small income property near the future interchanges in Kathu, purchased at a price that has not already priced in the expressway. The gap between transaction price and asking price on Phuket often reaches 10-15%, and negotiating that gap needs to happen now, before construction begins.

Before buying, drive Patong Hill yourself, once at seven in the morning and once at six in the evening. It is worth seeing the real traffic pattern with your own eyes before committing to a purchase decision.

FAQ

When will the Kathu-Patong expressway actually open?

The target date for Phase 1 is 2031, contingent on Cabinet approval in December 2026 and construction starting in October 2027. Given the project's history of delays, it is wise to factor in a 1-2 year slippage.

How much will the toll cost?

The rate has not been finalized. Differentiated pricing by vehicle type, from motorbikes to heavy trucks, has been discussed. For daily commuters, this would become a meaningful line item.

How much will Kathu property prices rise?

No one can give an exact figure. Experience with transport corridors in Bangkok shows that most of the price gain lands in the 18-24 months before opening and the first year after. I would not bet on prices doubling in five years based on the road alone.

Can a foreigner buy land along the route?

Not directly. Available structures are long-term leasehold registered with the Land Department, or a stake below 50% in a Thai company. The company route requires genuine business activity and is subject to regulatory scrutiny.

Which is the better buy: Patong or Kathu?

Patong offers higher seasonal yield but fiercer competition for tenants. Kathu is cheaper to enter and stands to benefit more from the tunnel. For a purchase horizon running to 2031, I would choose Kathu.

Will construction disrupt the neighborhood?

Yes, and negatively in the short term. Three to four years of works mean noise, heavy machinery, and traffic restrictions near the tunnel portals. Properties close to the construction site may see rental rates soften during that period.

Should I wait for Cabinet approval in December 2026?

If you are negotiating on a specific property, no, waiting does not pay off, since approval will immediately show up in seller expectations. If you are considering a speculative land purchase, wait until the budget is confirmed.

Are there other infrastructure projects affecting Phuket prices?

Airport expansion, an island-wide rail transit concept, and an upgrade of Road 402. Of these, only the expressway has reached the stage of concrete dates; the rest remain on paper for now.

If there is one takeaway, it is this: treat Kathu-Patong as a factor that improves an asset's liquidity on exit, not as a source of income. Buy what you are willing to hold and rent out even if the tunnel ends up opening in 2034.

Source: The Thaiger

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