In June 1942, the Japanese Imperial Armay began construction of the 415 km Burma-Thailand Railway to provide an alternative supply route by sea, west of the
Malay Peninsula. It started 40 km west of Bangkok, crossed Thailand and Burma and finished east of Rangoon. The new supply route was intended to support
a planned invasion of India by the Japanese.

What they don't tell you in the movie is that there were two bridges spanning the River Kwai during World War II. The original wooden bridge was completed
in February 1943. A second 11-span concrete bridge (shown here) was completed in June 1943. The Japanese brought it in pieces from an oil field in Java and used
P.O.W.s to recontruct it.

The part of the river where the remaining bridge stands is about two kilometers north of where the River Kwai Yai (Big Kwai) joins the River Kwai Noi (Little Kwai)
to form the Mae Klong.

By the way, Kwai is pronounced 'Kwae' in Thai. The 'ae' has the sound 'a' in bat or Matt.