Just remembered an important piece of information if you are likely to go from Thonburi to see the River Kwai.
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The windowless train at Thonburi

This is it. The train goes very fast, and progresses in a kind of bounce. There is a toilet in between carriages, and these are of the 'high'squat kind. Well, a high squat toilet (made of metal) is quite a climb up, and of course the floor is a bit wet. My problem was how to balance on the high sides of the toilet, while securing trouser legs up round the calfs, keep the door closed as the catch was not very secure, and balance while the train careered on its way. Only one handle, not very helpfully positioned. The position was very perilous to say the least. You just have to grit your teeth and go with the bounce. (I speak as a female trying to do a pee).
On the return trip I disregarded all the instructions instilled in me since childhood: "Please do not use the lavatory while the train in standing in the station". I confess that this is just what I did (mind you the train was miles from anywhere and it was a very rural setting!