Route 42 (Thai: ทางหลวงแผ่นดินหมายเลข 42) as known Khlong Ngae - Su-ngai Kolok Highway or Phetkasem Road of Pattani-Narathiwat[1] in time when traveling from Pattani to Narathiwat.

Before highway numbers were assigned The road in the Pattani-Narathiwat section is called Pattani–Narathiwat Highway Later it was named Ramkomut Road on December 10 1950, when Field Marshal P. Pibulsongkram was Prime Minister.

In honor of Luang Parinya Yokhawibun (Chom-Ubon Ramkomut), the master technician who supervised the construction.

[4] South Korean company, Hyundai Engineering & Construction (Including the former president of South Korea, Lee Myung Bak) also involved in the construction of Pattani (Don Rak)-Narathiwat highway section as supervisors in 1965, which is now locals called Korean Road.

[2] In the past, Highway 42 usually routed from Ban Khlong Ngae, Sadao District , Songkhla Province to Ban Don Yang, Nong Chik District , Pattani Province.