Motorway 6 (Thailand)

Motorway 6 or the Bang Pa-in–Nakhon Ratchasima Motorway is an under-construction controlled-access highway, part of the Thai motorway network. It will serve as the arterial link from the capital city of Bangkok to the city of Nakhon Ratchasima, which serves as the gateway to the entire northeastern region.

The motorway begins with links from Kanchanaphisek Road (Motorway 9) and Phahonyothin Road (Highway 1), near the Bang Pa-in Interchange in Phra Nakhon Si Ayutthaya Province north of Bangkok, and leads northeast through Saraburi Province, passing through the Dong Phaya Yen pass before entering the Khorat Plateau and terminating at Nakhon Ratchasima Bypass Road (Highway 204). It runs a distance of 196 kilometres (122 mi),^[1] with elevated sections as it passes through the mountains, including one where it is elevated over Mittraphap Road as it runs along the edge of the Lam Takhong Reservoir.^[2][3]

The project was conceived in 1997 as part of the national highway network master plan (and one of three segments serving the northeast region), but construction only began in 2016. It was originally scheduled for completion in 2020, and construction was reported to be 96 percent complete by then,^[4] but the project faced delays due to outdated information from surveys conducted since 2008, necessitating modifications to the designs and extensions of the budget. By 2022, it was expected to open in 2025,^[5][1] though full opening has since been pushed back to at least 2026.^[6] The section between Pak Chong and Nakhon Ratchasima was opened for persistent trial use in June 2024,^[7] following earlier special trial openings during the New Year's and Songkran festivals.