Kanchanaphisek Road

This was the first section to be constructed in 1978, between Taling Chan district, Bangkok and Bang Bua Thong district, Nonthaburi, as part of Highway 340 to Suphan Buri. This section was later extended to Bang Pa-in district, Phra Nakhon Si Ayutthaya in 1995. The section between Taling Chan district with Bang Khun Thian district was completed in 1998.

The eastern section was completed in 1998 as a four-lane intercity motorway with toll collection. This was expanded to 6-8 road lanes in 2010 to handle the increased traffic after the opening of Suvarnabhumi Airport. On 15 February 2022, it was the first highway which the Department of Highways introduced the multi-lane free flow system (M-flow) to reduce congestion at the toll gates. As of April 2023, approximately 110,000 cars use the system daily.[3][4]

The southern section was the final section to be constructed and is a controlled-access toll highway. It opened for trial use on 15 November 2007 and toll collection between Bang Phli - Suk Sawat began on 23 March 2009. Toll collection was extended to the Suk Sawat - Bang Khun Thian section on 20 May 2019. Kanchanaphisek Bridge, the southernmost river crossing of the Chao Phraya River is part of the highway.[5]

According to an official EXAT annual report, the expressway was used by 79,603,350 cars in the 2022 fiscal year, with an average of 225,505 cars per day.[6]

The Kanchanaphisek Expressway (South Kanchanaphisek Road) is located almost entirely in Samut Prakan province.

Kanchanaphisek Expressway
Location	km	Northbound		Facility		Southbound
		Exit destinations (road)	Toll Plaza (Entry)	English	Thai	Toll Plaza (Entry)	Exit destinations (road)
Samut Prakan	0.00	Suvarnabhumi Airport, Chonburi ( Burapha Withi Expressway, Debaratna Road)	-	Wat Salut Interchange	ต่างระดับสัดสลุด	Bang Kaeo	-
		Bang Na, At Narong ( Burapha Withi Expressway, Debaratna Road)
	5.29	Bang Phli ( Thepharak Road)	Thepharak	Thepharak Interchange	ต่างระดับเทพารักษ์	Thepharak	Samrong ( Thepharak Road)
	10.82	Samut Prakan (Srinagarindra Road)	Bang Mueang	Bang Mueang Interchange	ต่างระดับบางเมือง	Bang Mueang	Bang Kapi (Srinagarindra Road)
	14.62	Samut Prakan ( Sukhumvit Road)	Pak Nam	Sukhumvit Interchange	ต่างระดับสุขุมวิท	Pak Nam	Samrong ( Sukhumvit Road)
	18.90	Pu Chao Saming Phrai Road	Pu Chao Saming Phrai	Bhumibol Bridge Interchange	ต่างระดับสะพานภูมิพล	Pu Chao Saming Phrai	-
		Rama III Road (via Bhumibol Bridge)
	20.30	Kanchanaphisek Bridge
	21.10	Phra Pradaeng, Rat Burana ( Suk Sawat Road)	Bang Khru	Bang Khru Interchange	ต่างระดับบางครุ	Bang Khru	Phra Samut Chedi, Chulachomklao Fort ( Suk Sawat Road)
Bangkok	36.66	-	Bang Khun Thian	Bang Khun Thian Interchange	ต่างระดับบางขุนเทียน	-	Bang Pakaeo Intersection, ( Rama II Road)
							Samut Sakhon ( Rama II Road)