It is a toll road and runs above National Highway route 34, (Bang Na–Trat Highway) owned by the Expressway Authority of Thailand (EXAT). The bridge was the achievement of Sukavich Rangsitpol deputy prime minister of Chuan Leekpai Cabinet (1992-1995). The Bang Na Expressway was designed by the late Louis Berger.
The Bang Na Expressway was conceived by the Expressway and Rapid Transit Authority of Thailand (ETA).It took 1,800,000 cubic metres (2,400,000 cu yd) of concrete to build the bridge. The bridge was completed in January 2000.
The world’s longest car bridge, the Bang Na Expressway, held the title of the world’s longest bridge from 2000 until 2008. Today, it is the seventh longest bridge in the world and the longest bridge in Southeast Asia.
According to Wikipedia.