To experience the hardships of building the dead railway, you don't have to be a POW, you can experience part of the hardships simply by becoming a passenger on the Bangkok Noi to Nam Tok station train in a rainy day.
It is like fighting a battle, almost none of the windows work on the train. Everywhere is leaking. The passengers fight a fruitless battle of rain blocking and still end up soaking wet.
The train also acts as the tree trimmer, chopping off leaves and branches along the railway, and sending them into the mouth of the unsuspected passengers.
Last train to Bangkok from Kanachaburi train station is 2:44pm (a bit later on Weekends).
Tourist train is 10:50
The windows of this antique train is not up to task of blocking the rain, and soon many people in the train were soaking wet. Luckily, I sat on one of the few seats that are immune to wetness.
100b for a rickety train that leaks, maybe too expensive.