The Department of Highways plans to start building an elevated expressway extension on Route 338 (Boromratchachonnani, Phutthamonthon Sai 3 to Sai 4, 4.63 km, 4,386 million baht) in January 2027, with completion targeted for January 2030. Work is split into 6 contracts. Traffic will be closed in phases, one lane each side at first, and the road carries about 265,982 vehicles a day. If your business sits on or relies on this corridor (Nakhon Pathom, Phutthamonthon, Thonburi deliveries), plan alternate routes such as Phran Nok new road, Phutthamonthon Sai 4, Phetkasem/Rama 2, and M81, and budget for delivery delays. The start depends on the M82 motorway opening first and on final approval of the closure plan, so the date may move.