Phuket's Gateway Road to Get Wider: What the Route 402 Expansion Means for Investors

Phuket's only road link to mainland Thailand is finally set for an upgrade. Officials are moving forward with plans to widen a 2.27-kilometer stretch of Highway 402, running from Sarasin Bridge (via Thepkrasattri Bridge) to the Tha Chatchai checkpoint, the island's sole land border crossing.

Phuket Governor Nirat Pongsitthaworn, together with the Phuket Highway District, has already reviewed the project. Design work is being carried out jointly with Thailand's Department of Highways and outside consultants. The coastal highway (Route 4302 near Mai Khao) is not part of the plan; this project targets only the main entry point onto the island.

For anyone living on Phuket or holding property here, this is more than a roads story. It's a signal of how the island's infrastructure is trying to catch up with its own growth.

Key Facts

• The widening covers 2.27 km of Highway 402, from Sarasin Bridge / Thepkrasattri Bridge to the Tha Chatchai mangrove area

• Route 402 is Phuket's only full road connection to the mainland; there is no alternative route

• The project is overseen by Governor Nirat Pongsitthaworn with the Phuket Highway District

• Design work involves Thailand's Department of Highways, with a 15-month study that began in March and is due for completion by June 2027, according to The Phuket News

• Options under review include a four-lane (or wider) road with a raised or depressed median, or an elevated section

• The coastal highway near Mai Khao is excluded from the scope

• The plan also covers the Tha Chatchai checkpoint, the island's only land border crossing

• News of the project surfaced in June 2026; construction dates have not yet been announced

Story and Context

Phuket is an island. It sounds obvious, but almost nobody buying a condo or villa here fully appreciates the consequences. The entire logistics chain of the island runs through one bridge crossing near Thepkrasattri. Construction materials, groceries, fuel, and tourists all pass through the very same 2.27-km stretch of Route 402 that is now up for expansion.

The original Sarasin Bridge, built back in 1967, has long since become a pedestrian crossing, replaced by the parallel Thepkrasattri Bridge. But the capacity of the approach road has barely changed in decades, even as Phuket transformed from a fishing province into one of Southeast Asia's most expensive property markets. Colliers Thailand has projected that Phuket property prices could rival Bangkok and other global cities by 2026, a pace of growth the island's roads were never built to support.

Anyone who has driven from the airport during high season knows the congestion at the island's entrance. But the real bottleneck hits during long Thai holidays: Songkran, Loy Krathong, New Year. On those days, queues at the Tha Chatchai checkpoint can stretch for hours. The checkpoint was designed for vehicle inspection, not for handling the volume of traffic it now sees daily.

There's a less obvious layer too. The Tha Chatchai mangrove zone is an environmentally sensitive area, and any road widening here requires sign-off from conservation authorities. That's exactly why outside consultants have been brought in: the road can't simply be paved wider along its shoulders. Phuket's mangrove forests are protected by law, and any clearing will likely require compensatory replanting, part of the reason the study is expected to run 15 months, from March through to a targeted completion of June 2027.

For property owners in the north of the island, in areas like Mai Khao and Nai Thon, this expansion is a direct value driver. The northern stretch of Phuket has long been perceived as 'far' precisely because of congestion at the island's gateway. A smoother approach road would cut travel time from the mainland provinces of Phang Nga and Krabi, widening the labor pool and making northern Phuket more attractive for long-term rentals.

It's worth noting the broader picture: Thailand has been investing heavily in southern infrastructure in recent years, from airport modernization to ongoing discussions of high-speed rail. None of those larger projects has been completed yet, but the Route 402 widening is the most realistic in terms of timeline. A Phuket real estate industry group has separately urged the central government to speed up infrastructure spending islandwide, citing insufficient road capacity, missing intersections and tunnels at congestion points, strained water and drainage systems, and a waste incinerator at Saphan Hin already operating beyond capacity, evidence that demand on Phuket is outpacing what its infrastructure can absorb.

As for cost, Department of Highways projects are funded from the national budget. A comparable widening project in Chonburi province (the Pattaya area) cost the Thai treasury several billion baht. Given the terrain and environmental constraints here, the Phuket stretch could carry a comparable price tag.

If you're planning to fly into Phuket to view properties, keep in mind that until the widening is finished, transfers from the airport to the island's southern districts during peak hours will take noticeably longer than any map application suggests.

Source: The Phuket News

FAQ

Which road is being widened on Phuket in 2026?

The 2.27-kilometer stretch of Route 402, the main road linking the mainland to the island, from Sarasin Bridge / Thepkrasattri Bridge to the Tha Chatchai area.

Will the project affect Phuket's coastal highway?

No. The coastal highway, Route 4302 near Mai Khao, is excluded from the project. The widening applies only to the island's main gateway road.

When will construction start?

As of June 2026, the project is at the study and survey stage. A 15-month study began in March and is expected to be completed by June 2027; specific construction start dates have not been announced.

Why does the Route 402 widening matter to property owners?

Route 402 is Phuket's only full road connection to the mainland. Its capacity directly affects construction logistics, cost of living, and how attractive the island's northern districts are to renters and buyers.

Are there environmental constraints on the project?

Yes. The route passes through the protected Tha Chatchai mangrove zone, which adds complexity to the design process and could extend the timeline.

Who is funding the road expansion?

The project is led by Thailand's Department of Highways and funded from the national budget.

How will the project affect traffic congestion at Phuket's entrance?

Widening the road and upgrading the Tha Chatchai checkpoint, potentially to four lanes or more with a raised or depressed median or an elevated section, should increase capacity. The real-world impact will depend on the final design and how quickly traffic volumes keep growing.

Is a second bridge to Phuket being considered?

The idea occasionally surfaces in Thai media, but as of 2026 there is no approved project for a second bridge. The Route 402 widening is the more realistic initiative already underway.

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