[mars]

The train does stop at the bridge and its the first stop after Kanchanburi 5 minutes away. If you get off you wont have time to look around and get back on to go to Nam Tok.

You could catch the later train to Nam Tok but wouldnt have any time there and after the 3 hours to the bridge you wouldnt want to go any further due the wooden seats.

What I did was catch the train to the bridge, have night in a hotel, next day have a day trip to Nam Tok, another night in the hotel and caught the bus back to Bkk the next day.

Note - There's not a lot to see from the train traveling from Bkk to Kanchanburi but the scenery is worth seeing off the train from Kanchanburi to Nam Tok. You can aslo walk over the bridge and back.

Search for Kanchanburi in the "Issan and other cities" part of the forum you will find more on the subject and some pics I posted there.