Motorway 81 (Thailand)

Motorway 81 was included in the 8th National Economic and Social Development Plan in 1997. The Bang Yai–Ban Pong section was approved by the 53rd Cabinet in 1998, and the Ban Pong–Kanchanaburi section received approval from the 54th Cabinet in 2003. Design studies and field surveys for the Bang Yai–Kanchanaburi section were conducted between 2008 and 2009.^[3][4]

Construction began in 2016; however, detailed field surveys revealed that the number of affected land plots, structures, and trees significantly exceeded initial estimates. Rapid land development and new projects along the alignment had substantially altered land use conditions compared to original assessments. These discrepancies led to a construction halt lasting over two years.^[5][6] Land expropriation compensation was fully disbursed to all 4,571 affected property owners by 20 December 2019. At that time, civil engineering works were only 25.05% complete, falling 56% behind the original schedule.^[7]

Following the completion of land acquisition, construction progressed steadily toward completion. The motorway was initially opened for temporary trial runs during select periods. It subsequently opened for 24-hour trial operation on 31 October 2025, prior to its full commercial opening on 16 January 2026.

Toll collection on Motorway 81 began on 16 January 2026 following a period of free trial operations that commenced on 31 October 2025.^[8][9] The motorway uses a distance-based tolling system consisting of an entry flag-fall fee plus a rate per kilometer, collected across eight toll plazas along the 96-kilometer (60 mi) route.^[10]

Toll rates are categorized by vehicle classification as follows:^[11]

• 4-wheel vehicles: ฿10 entry fee + ฿1.50 per km (maximum ฿150 for the full route)
• 6-wheel vehicles: ฿16 entry fee + ฿2.40 per km (maximum ฿240 for the full route)
• Vehicles with more than 6 wheels: ฿23 entry fee + ฿3.45 per km (maximum ฿350 for the full route)

Payment options at the toll plazas include cash, electronic toll tags (M-Pass and Easy Pass), and the barrier-free automated license-plate recognition system (M-Flow).^[12]