Below you'll find the november 1998 version of the page on Train stations and Refuge Depots. The ideas on this particular item are in need of re-evaluation due to the Pathfinding algorithm theory.

Which terminus-type to use
Basically there are two kind of train stations: a through station (on route between two other stations) and a terminus (the end of the railway line). The first doesn't appear that often and if it does it's kind of straight forward. The terminus however can either be a standard or a 'Roll on, Roll off'-type (RoRo). Refer to Wolfgang Preiss' article on advanced railway construction for the basic lay-outs.

The advantage of a RoRo station is that trains entering the station do not use the same section as trains leaving. In a standard terminus only one train is allowed on the section to and from the station, whether trains will cross one anothers track or not. Once a station has a lot of trains servicing it, the RoRo station will earn you much more money. Use a standard terminus (up to 4 tracks wide) for passenger, mail and/or valuables services. The reason being that it's easier to establish a good functioning standard station in the heart of a town rather than a RoRo one. However, if many trains service this station, especially if it has 1 or 2 tracks only, it's likely to be a bottleneck in your system.

Since space is usually plentifully available near natural resources and industries, you can and often should use RoRo-stations there. Although it will not be necessary in the beginning, the natural resources can increase their output over a period of time, to as much as 8 times the original.
If you manage to transport all that to receiving industries (i.e. factories, steel- and/or sawmills) they will follow suit. Designing a well tuned railsystem will pay off then! This is particularly the case at factories since they will get trainloads of livestock and grain as well as steel to handle. It is a challenge indeed to succeed in bringing all those trainloads to a single factory.
However, you can use more than 1 station for this!

At factories (or other secondary industries) it's often best to use different (RoRo-)stations for the unloading of the incoming resourses, and the loading of the goods produced. Otherwise at some point (particularly during a worldwide recession and long after the economy had an upturn!) you'll find all tracks occupied by trains waiting for goods to be produced.
Trains carrying the grain, livestock and steel can't enter, causing mayhem to your operation.
To unload: use a 4-track (RoRo-) station (especially when you're concentrating all incoming farm- and steelmill products to one factory).
For loading goods a one-track station will initially suffice. However when output increases you need more tracks to shift all the goods produced.

Farms need some extra attention. They produce the same quantity of livestock and grain. Transport-wise there is a difference. Livestock is ('full load') taken in multiples of 25 units and grain in multiples of 30. One way to solve this inequity is to have 6 livestock wagons for each 5 grain wagons.

Mandatory Service
Wolfgang Preiss advises to have depots at the end of each track (standard terminus). This way all trains will enter a depot after (un)loading and only then leave the station (forced maintenance).
His advise is valuable since the trains will not wander off looking for service due to being 150 days without service. The disadvantage is that if we use this standard terminus in urban areas, these depots occupy spots where big passenger/mail producing buildings might be,

All terminus tracks are occupied
Another problem you should address is when all tracks of a terminus (both standard and RoRo) are occupied. Occasionally a train arrives at a station when all tracks are occupied. Let's consider what happens in case of both a RoRo-terminus old style and a traditional terminus old style.

Problems with RoRo-terminus old style
A train will enter the first available track it can find. So in the picture on the left it passes by tracks 1, 2 and 3 to try it's luck at track 4. Because that one is occupied too the train will wait in front of track 4 for that particular track to come free. Since this track is the furthest away it's very likely that it was the last one to be occupied and therefore the last one to be cleared. Our train will stick to it's choice and wait even when tracks 1,2 and 3 become available. This jam can easily spread itself to other parts of your system, like a main line towards this station if there are many trains behind the waiting train. This will cause a drop in revenue not just from the one train waiting for it's designated track to clear but for many more trains as well. So a special technique is called for: Refuge Depots!

RoRo-terminus with Refuge Depots (1)

All the tracks are occupied and the train disappears into the depot.

RoRo-terminus with Refuge Depots (2)

Right after entering the depot the train appears again to check for a free track. Since it doesn't find any it disappears into the depot on the other side. This will go on until any track becomes available!

What are the advantages?
First of all trains will enter a free track as soon as it becomes available, thus improving revenue! The trains commuting between depots will not wait in front of a certain track while other tracks are free. Another advantage is visible in the second picture. A new train has gotten to the signal giving access to stations entrance. So Trains will not pile up anymore either. Actually, they still pile up if the number of trains commuting between depots grows. But the rate of this happening is reduced considerably.

Last notes on Roro's
The tracks on the top edge of last 3 pictures leed into another depot to ensure mandatory servicing. Then trains will go to their next destination. Here you can see the importance of difficulty settings. If trains could reverse both at the end of line and at stations the detour via a depot/forced maintenance might make some trains turn inside the station. Of course the 1-way signals would prevent them from going far but it sure will not help your operation. In fact, if trains need to wait too long before they leave the station they turn around and run into either one of the 2 refuge depots. From there they can't find their next destination and commute between the depots untill it is adjusted manually. The terminus in the picture is used for unloading only. If you have the same setup for loading you have to allow for the following. If during loading a train is rushed off for mandatory service by the AI (for instance due to waiting for a full load) it will have a difficult time finding it's way back to the station.

Problems with Standard terminus old style
One of two things will happen. Neither does your operation any good. The first possibility is basically just like what happens at a terminus. An incoming train will stop for the last (occupied) track it finds, blocking the whole intersection. No train can enter or leave the station until the train occupying the designated track will disappear in the depot at the end of the track (if you put one!). Not a scenario which will give you tycoon status, or is it?

The second scenario is even worse. Often the layout at a terminus allows a train to turn away from the station. It will still have the station it passed by as his first port of call.

Refuge depots at a standard terminus

The incoming train will commute between both depots until one of the tracks is cleared. Since the section outside the terminus is cleared every other moment, trains will be able to depart. Take note of the special layout of the tracks outside the station. Trains can not continue their journey without entering the terminus. The tracks leading away are accessible only from the station tracks.

Final thought
Now that we have a technique to handle an overflow efficiently there is no longer a need to build 4-track stations at every city. In all examples shown there weren't any mandatory service depots to be seen. Ordinarily you want to put them after any station, before the spot where tracks split into different destinations.