The Kanchanaphisek Outer Ring Road (southern section), and in particular the Chao Phraya Bridge, has been a stop-and-start project since it was first conceived in 2001 and announced by Bangkok governor Samak. The 20km (12 mile) section of motorway will fulfil several functions by completing the connection around the city, and providing a road link to the new Bangkok International Airport at Nong Ngu Hao, Suvannabhum, which opened in 2006.
The river crossing was actually planned as a dual tunnel system when the project was first conceived; however engineering problems with the geology beneath the river bed and cost issues ruled this out at an early stage.
The bridge for the Kanchanaphisek Outer Ring Road was designed by Parsons Brinckerhoff of New York who has had much experience in Thailand and with bridges of this type. Parsons Brinckerhoff are acting as designers and architects and offering engineering, project management, construction supervision and technical support services for the duration of the project.