Phet Kasem Road

Phet Kasem Road (Thai: ถนนเพชรเกษม, RTGS: Thanon Phet Kasem, pronounced [tʰā.nǒn pʰét kā.sěːm])[1] or Highway 4 (Thai: ทางหลวงแผ่นดินหมายเลข 4, ) is one of the four primary highways in Thailand, along with Phahonyothin Road (Highway 1), Mittraphap Road (Highway 2), and Sukhumvit Road (Highway 3). At 1,274 km, it is the longest highway in Thailand. It begins at Naowa Chamnian bridge in Bangkok Yai, Bangkok. It is named after Luang Phet Kasemwithisawasdi, the seventh director general of the Department of Highways.

National Highway 4
ทางหลวงแผ่นดินหมายเลข 4
ถนนเพชรเกษม Thanon Phet Kasem
Road sign in Ratchaburi
Route information
Part of
Length	1,274 km (792 mi)
Existed	1950–present
Major junctions
North end	Bangkok
South end	Sadao checkpoint, Malaysia–Thailand border
Location
Major cities	Nakhon Pathom, Chumphon, Phatthalung, Hat Yai, Sadao
Highway system
Highways in Thailand Motorways Asian Highways

The provinces along the road are Samut Sakhon, Nakhon Pathom, Ratchaburi, Phetchaburi, Prachuap Khiri Khan, Chumphon, Ranong, Phang Nga, Krabi, Trang, Phatthalung and Songkhla. It is linked to the North–South Expressway (NSE) of Malaysia at Sadao and Bukit Kayu Hitam passes.

Three sections of the highway are also the Asian Highway AH2.

• From Nakhon Pathom to Chumphon
• From Phatthalung to Ban Khu Ha
• From Hat Yai to Malaysia border, where it connects to the North–South Expressway (Malaysia)