Prachim Ratthaya Expressway

The Prachim Ratthaya Expressway (ทางพิเศษประจิมรัถยา), also known as the Si Rat–Outer Ring Road Expressway (ทางพิเศษสายศรีรัช–วงแหวนรอบนอกกรุงเทพมหานคร), is an expressway in Thailand, located in Bangkok and Nonthaburi province. The expressway is a controlled-access toll road.

History
Prachim Ratthaya Expressway was completed and opened in its entirety on 22 August 2016. It connects Si Rat Expressway to Outer Ring Road (West) (Kanchanaphisek Road). The expressway's name Prachim Ratthaya was bestowed by King Vajiralongkorn, meaning "Road to the West".

According to an official EXAT annual report, the expressway was used by 18,466,598 cars in the 2022 fiscal year, with an average of 50,594 cars per day.

Route
Kilometre 0 is counted at Kanchanaphisek Interchange.