The six-lane, 669-meter long underpass, not only alleviates traffic problems at the Ratchaphruek-Nakhon In intersection but also increases the efficiency of the transport network on the western bank of the Chao Phraya River, facilitating transportation to and from the Inner Ring Road (Ratchadaphisek Road) and the Outer Ring Road (Kanchanaphisek Road), linking to a larger travel network from the suburbs to the city center