Most foreign visitors travel second class, either aircon or non-aircon. For second class aircon and second class non-aircon , and of course in first class , sleeping berths are available on long distance trains. Ordinary trains are slowest, and they often only have third class carriages. Rapid , express , and special express are fast long distance trains. The difference in speed among the three of them is not really sufficient reason for choosing the one and not the other.
Special express is a little bit faster than express, and express a little bit faster than rapid.
There are also diesel rail cars and special diesel rail cars . The ordinary carriages only operate on the eastern line, and there are no other trains there. The special rail cars go on the northern line from Bangkok up to Phitsanulok, and on that stretch they are even faster than special express trains. The following supplementary charges are in effect, regardless of the distance traveled on a train. Second class non-aircon berth on special express trains, upper 100 Baht, lower 150 Baht.