Types

In addition to the standard signals from the original TTDX, there are now several new signal types, some only available in TTDPatch, others only in OpenTTD. They all offer new functionality and can solve certain problems, but also lead to new headaches, if their functions are not completely understood. This page introduces the various signal types, detailed explanations are given on extra pages.

This page only introduces the signals. The question "And how do I use them correctly?" is discussed on the pages about networks and stations!

standard signals

Standard signals show "Stop!" if there is a train in the signal block behind them. Thus there can only be one train in a signal block at any given time, which prevents any collisions. The behaviour of these signals is rather easy to understand, however they are also quite limited when it comes to complex signalling tasks.

Usage

The only useful task left for them is the forming of signal blocks on rails which should be used in only one direction. The principle of such a block is the base for doubletracked networks and is explained there in detail.

pre-signals

Presignals were the first new signals that have been introduced. The main goal was to solve problems with station entries, which was not possible with the standard signals.

There are three types of presignals: Entry, exit and combo, with the combo signal being a combination of entry and exit. The criteria for these signals to show "Go!" or "Stop!" are a bit more complex and are explained in detail on an extra page.

Usage

By now these signals are only interesting for very specific tricks. Path signals are much simpler to understand and offer a more flexible approach. So, presignals have become almost obsolete.

path signals

YAPP stands for Yet Another Path-based signalling Patch and implements path-based signalling in OpenTTD. This implementation has thrown away several limitations of the older signal types, leading to a very simple and elegant solution, which can solve just about any signalling problem. There is an extra page for the detailed introduction.

Usage

Always and everywhere! Especially for newcomers to the game, path signals are much easier to understand, because one does not have to mess around with the various pre-signals types.