Hua Lumpung Station to Butterworth StationMy friends and I bought our train tickets a month before our trip. It cost 1,210 baht for one way trip. It is just a 2nd class sleeper. The train leaves at 2:45 pm daily. It is a 22-hour journey from Hua Lumpung to Butterworth. For train timetables visit
http://www.seat61.com/Thailand.htm#Train%20times.

Inside the trainThe train has upper and lower berth. At daytime, you can sit on it. If you want to take a nap, then you can squeeze yourself on the chair.
Some seats have a table in the middle so that you can play cards or anything. Unluckily we don't have. A pillow and a blanket is provided. No meal inclusive yet you can order food. Or you can simply go to the restaurant to eat.
This is how it looks like during daytime.

At night the attendant will assemble the chair into bed. And he put the curtains for privacy purposes.

The lower berth at night.

The upper berth is smaller compared to the lower berth.

There is a toilet and a sink inside the train. Although it is not so clean.
The first stopover is in Hat Yai. They will exchange cars here. It takes 10-15 minutes of waiting.

The second stopover is in Padang Besar (border between Malaysia and Thailand). The passengers need to disembark along with their baggage. Although I found some passengers left their bags. The immigration officers will stamp your passport. And the custom officer will check your baggage. After that you can hop on the train again. It takes 30 minutes in the immigration office depending on the number of passengers.

The exchange rate here is higher compared at the airport or train stations. Although the train attendant also sells ringgit if you asked. For exchange rates, visit
http://www.xe.com.
After almost 2 hours we arrived in Butterworth station from Padang Besar.