Phahonyothin Road
It begins in Bang Pa-In District in Phra Nakhon Si Ayutthaya Province at the junction of Phahonyothin Road (Thailand Route 1) and the Outer Bangkok ring road (Motorway 9), then passes through the provinces of Ang Thong, Singburi, and Chainat, where it merges back into Phahonyothin Road directly at the border with Nakhon Sawan Province.