This time, the real one. Almost. The railway is indeed the Burma railway, built during the WW2 by the Japanese using some 160k Asian slave workers and 40k allied POWs. The bridge was also there but not the river itself. The award winning movie made the setting famous, so in in 1960 the Thai government renamed the Mae Klong river as Kwai. The steel bridge was originally constructed in Java but was dissembled in 1942 and rebuild here. Some of the original trestle viaducts are still in use.