Phuket expressway’s Kathu–Patong phase headed for Cabinet approval in December

Thailand’s Expressway Authority (EXAT) plans to seek Cabinet approval in December 2026 for revised details of the first phase of Phuket’s planned expressway, a 3.98-kilometre route linking Kathu and Patong.

The first phase is estimated to cost B16.757 billion, including B5.792 billion for land acquisition and B10.965 billion for construction and supervision. EXAT Governor Surachet Laophulsuk said land acquisition was 99.43% complete.

The revised plan reduces the width of the tunnel beneath Nak Koet Mountain from 17.1 metres to 14.2 metres while retaining its 1.85-kilometre length. EXAT said the change reflects construction-material and fuel costs, geological study findings and requirements related to earthquake resistance.

The tunnel is designed for cars and motorcycles, with four traffic lanes separated by safety barriers. EXAT estimates that the route would cut travel time between Kathu and Patong from about 30 minutes to five minutes.

Proposed tolls are B10 for motorcycles, B20 for four-wheel vehicles, B40 for vehicles with six to 10 wheels and B60 for vehicles with more than 10 wheels. EXAT estimates daily revenue of about B960,000 and an economic internal rate of return of 19.47% for the first phase.

Second phase and funding

The second phase, linking Mai Khao, Ko Kaeo and Kathu, would cover 30.62 kilometres and cost about B67.461 billion. EXAT is preparing the detailed design, which is expected to be completed in January 2027, with Cabinet consideration targeted for October 2027.

The route would include at-grade and elevated sections, as well as a tunnel through the Kamala mountain range, before connecting with the first phase near Highway 4029. A proposed spur at Ma-Nik 2 would direct traffic towards Phuket town. EXAT also plans a 37-rai service area and a 13-rai rest stop, both of which would be opened to private investment.

EXAT said rising global construction costs could mean that financial returns from the second phase would not cover borrowing costs. The authority is reviewing ways to reduce construction costs while maintaining safety standards.

EXAT is also discussing an infrastructure fund with the State Enterprise Policy Office. Under the preliminary plan, about B1 billion a year from EXAT’s income could support the fund, including revenue from the Bang Phli–Suksawat expressway, which currently generates about B2.6 billion annually in tolls. Systems, toll collection and operations and maintenance would be offered to private investors under a public-private partnership model.

EXAT plans to complete the first phase’s terms of reference in April 2027 and begin construction in October 2027, with construction expected to take 48 months. Land acquisition for the second phase is planned for 2027–2030, with construction beginning in 2029. The authority aims to open both phases fully in October 2031, when combined traffic is forecast to exceed 50,000–60,000 vehicles a day.