Rail Building
  Part 1: Fundamentals

Most Transport Tycooners will find railways their most useful tool. Personally, I use trains for almost all of my cargo. Below is a list of popular layout styles for your game.

Layout
There are two main types of layout - point-to-point and anywhere-to-anywhere. Although there is no reason why you can't use both in one game, you may find it easier to stick to the anywhere-to-anywhere style, as explained below.

Point-to-Point
The point to point layout is the simplest layout possible, with the absolute minimum amount of track being built. The line goes from one station directly to the other. The problem with this style of design is each new station requires an entire new line. This is the style used by the AI with extremely limited success.

I personally never use the point-to-point system because it is too simple and inefficient. It's like connecting the dots - you can train a chimp to do it. Also, the requirement of new lines for each station can cause huge complex webs of tracks and stations, especially if there are only two factories or food processing plants on the map. A network layout is far better for these situations

Network
This refers to a layout where all or most of the stations are connected so a train can go from anywhere to anywhere. The good thing about this is you don't have to build an entire new line for each station, and you can send your cargo across the map easily without having to build more track.

Networks are by definition more complex than point to point layouts and as a result there are many problems associated with them.

• Lost trains. With complex networks, trains choose the wrong track at a junction. This could be caused by trains trying to go to a depot, or getting confused if they need to turn left to head right. Solving these problems is relatively simple with the usage of check points or placing depots in the trains orders using TTDPatch or by using better designed junctions or stations as explained through out the rail section of this site. Try not to build places where trains can do U-Turns.
• Higher initial costs. Compared to point-to-point, you need to initially build more tracks, tunnels and bridges, but over the long term there will be a saving as you can send several trains down one line.
• Traffic jams - When you try to cram too many trains down one track, or trains get lost and confused, gridlock is a common result. Once your trains are in gridlock, the only real way to get them out is by telling the train(s) at the frount to either change direction or ignore the signal. Use extreme caution when doing this as you may cause trains to collide - save your game first just in case.

Traffic jams can be avoided depending on the cause of the hold up. A well designed network will never have such hold ups, but that is almost impossible. If the problem is due to too many trains in one track, consider expanding the track. Sometimes its one bad junction. Through out this site there are many good tips on how to avoid this problem.

I personally always use networks for my rail layout and as a result, almost all the the rail section of this site relates to them.

Signals
Signals are the most important part of any good rail network. They prevent collisions and can be used to direct trains. There are two main types of signals, two way sigils, which trains can go through both directions, and one-way signals, which trains can only go through one direction, the direction the signal is facing. Trains behave differently with different signals. Consider the following:

	A train coming from the bottom of the picture heading towards a station left of the picture sees the two signals. If both are green, it will take the track which goes in the general direction of its destination. If one signal is red, however, it will choose the green one, even if it goes in the opposite direction it's headed. Rule: Use two-way signals if you want the train to choose a free track, like in multi-platform stations, for example. Placing two-way signals in front of each platform will make the train choose one that's free.
	But what if you want the train to choose the one that goes in the right direction, not the free one? Then you use one way signals. A train coming from the bottom, heading left, will chose the track heading left. If that signal is red, it will go left then stop and wait for the signal to turn green. Rule: Use one way signals if you want a train to choose the track that goes closest to its destination, such as at junctions where tracks split into two.
	What if you want to force the trains to choose one track only? Then you use two one way signals facing different directions. The train will not choose the track with the signal facing away from it. If it does, it will get to the signal, stop, turn around and go back the way it came. Rule: A train will never choose a track with a one way signal facing away from it. This could be very handy when forcing a train to go into a depot (see: Depots) .

Pre-Signals
Pre-signals are one of the greatest features of TTDPatch. The standard signals in the game are red if the track between it and the next signal, including all sidings, has a train on it. Once that train has past the next signal, the first one goes green. Pre-signals are different. The are red when all the next signals are red. This way, a train attempting to enter a station that is full will wait at the signal before the two-way signals at the start of the station, instead of waiting at the signal for the first platform it comes across. The pre-signals in version 1.7 are different to those in version 1.8. Here we'll talk about the advanced pre-signals in version 1.8.

	There are 3 types of signals that can be used in the pre-signal set up. The top one is an entrance signal. These are placed at the entrance of a pre-signal set up and are red if all of the signals in every possible direction down the track are red, providing they are of the next two types.
	The second type of pre-signal is an exit signal. It marks the end of the pre-signal block. These should usually be two-way signals so trains will "choose" green tracks over red ones. Exit signals are placed in front of the platform (assuming you're building a station) and behave like normal signals.
	The third type is a combo signal. These are a combination of an entrance and an exit signal. Like exit signals, these should usually be two-way signals so trains will "choose" clear tracks. If all exit and combo signals in a pre-signal set up are red, then the entrance signal(s) leading to them will also be red. Alternatively, if all combo/exit signals behind a combo signal are red, then it too will be red.

Placing these advanced signals is easy, but you'll need the pre-signals option (-w) activated in TTDPatch. If one or more one way signals leads to one or more two way signals then the end of the line(s) or another one way signal, then the first one way signal(s) will automatically become an entrance and the two way signal(s) will become an exit. The last one way signal will not change and any one way signals facing the opposite direction to the first signal(s) will not effect any pre-signal setup.
To manually place pre-signals, simply place a signal normally on the track, then ctrl+click it once for an entrance signal, twice for an exit, three times for a combo and a fourth time to return it to a standard signal. You'll need both the pre-signals option (-w) and the exit pre-signals option (-Xw) activated in TTDPatch.